Invited talks

Speaker Title Abstract
Gert Aarts Two topics in the QGP: diffusion of light quarks and parity doubling in the baryon sector I will discuss two topics in the thermal QCD, showing results from lattice simulations with 2+1 flavours: electrical conductivity/diffusion of light quarks and nucleons/parity doubling. For the first topic we find that the diffusion constant is around the value predicted for strongly coupled theories with a holographic dual. For the second topic we find strong medium modification of the N^* already in the confined phase and the emergence of parity doubling linked with the deconfinement transition.
Yukinao Akamatsu Open quantum system approach to quarkonium at finite temperature Quantum dynamics of quarkonium, such as charmonium and bottominum, in the quark-gluon plasma attracts much attention since the sequential suppression of Upsilon states is observed at the LHC heavy-ion experiments. At finite temperature, the naïve potential model picture needs to be modified in order to correctly account for the thermal fluctuation, which causes an imaginary part in the potential. In a broader perspective, a suitable framework for quarkonium at finite temperature is open quantum system approach, which is widely used in quantum optics and quantum dissipation. In this talk, I will review the applications of open quantum system approach to the physics of quarkonium in the quark-gluon plasma.
Constantia Alexandrou Selected results on hadron structure We will present selected results on hadron observables using twisted mass fermion simulations generated at physical value of the pion mass.
Silas Beane Nuclear structure from first principles I will describe recent progress in calculating the properties of nuclei from first principles using lattice QCD, with a focus on recent calculations of electromagnetic structure.
Nora Brambilla Heavy Hybrids with Effective Field Theories We discuss heavy hybrids using QCD nonrelativistic effective field theories.
Jiunn-Wei Chen Baryon susceptibilities, nongaussian moments and the QCD critical point We calculate model-independently the impact of the critical point on higher order baryon susceptibilities chi_n, showing how they depend on fluctuations of the order parameter. Including all tree level diagrams, we find new contributions to chi_4 equally important to the kurtosis of the order parameter fluctuations, and we characterize the kurtosis and other nonguassian moments as functions on the phase diagram. Important features of this analysis are then confirmed by a Gross-Neveu model study with good agreement with other model studies as well as lattice and experimental data. This suggests the universality of the characteristic peak in baryon susceptibilities as a signal of the critical point. We discuss leveraging measurements of different chi_n to extrapolate the location of the critical point.
Ian Cloet Insights into Hadron Structure from Continuum QCD Quantum Chromodynamics (QCD) is the only known example in nature of a fundamental quantum field theory that is innately non-perturbative and is the piece of the Standard Model of Particle Physics which is supposed to describe almost all of nuclear physics. Yet, almost fifty years after the discovery of quarks, we are only just beginning to understand how QCD gives rise to the building blocks of matter: pions, neutrons, protons and nuclei. This presentation will explore some of the most challenging problems in nuclear physics and describe some important insights that have been gained using QCDs Dyson-Schwinger equations -- a tool which encapsulates the two key emergent phenomena in QCD, namely, confinement and dynamical chiral symmetry breaking. Implications for current and future experimental programs will be highlighted, with an emphasis on the need for a strong interplay with theory.
Gilberto Colangelo Determination of the quark mass ratio Q from $\eta \to 3 \pi$ TBA
Marco Cristoforetti Integration on Lefschetz thimble: from heavy ion collisions to superconductivity Integration on Lefschetz thimbles is a recently proposed method to overcome the sign problem in numerical simulations of quantum field theories. In this talk we present our tentative strategy to apply the algorithm to different problems from condensed matter to the physics of heavy ion collisions.
Luigi Del Debbio Space-time symmetries on the lattice The gradient flow is a useful tool to explore the symmetries of a quantum field theory, and to define the corresponding Noether currents. In this talk we focus on the Ward identities generated by infinitesimal translations along the gradient flow, and discuss the possibility of a nonperturbative renormalization of the energy-momentum tensor on the lattice.
Philippe de Forcrand Progress in simulating lattice QCD at finite density TBA
Shinji Ejiri First order transitions in finite temperature and density QCD with two and many flavors We investigate the phase transitions of (2+Nf)-flavor QCD, where two light flavors and Nf massive flavors exist, aiming to understand the phase structure of (2+1)-flavor QCD. Performing simulations of 2-flavor QCD and using the reweighting method, we calculate probability distribution functions of many-flavor QCD. Through the shape of the distribution function, we determine the boundary of the first order region in the parameter space of the light quark mass, heavy quark mass and the chemical potential.
Michael Endres New avenues for noise reduction in QCD correlation functions Numerical studies of quantum chromodynamics (QCD) rely heavily upon stochastically estimated correlation functions in order to extract information about the spectrum of the theory, and the matrix elements of operators. A reliable determination of such correlators, however, is often hampered by an exponential degradation of signal/noise at late time separations. In this talk, I show that a nontrivial interplay exists between statistical noise and excited state contamination in correlation functions, and that under certain conditions, this interplay can be exploited in order to reduce the uncertainties on extracted quantities. I'll first illustrate the method with a two-state toy model, where the conditions required are cleanly exposed. I’ll then develop algebraic expressions for noise reduction, which are applicable to general matrices of correlations functions. Finally, I’ll apply the approach to single hadron correlators in QCD, and show that for some cases considered, up to a factor of three reduction in uncertainties is possible for extracted energies.
Evgeny Epelbaum Chiral effective field theory for few-nucleon systems at the precision frontier TBA
Kenji Fukushima Quark Production and Anomalous Currents in Strong Fields We discuss a theoretical formulation of the quark production in strong field backgrounds. We demonstrate that not only the particle production but also the anomalous currents can be correctly described by the lattice discretized numerical simulation.
Feng-Kun Guo XYZ In the last decades, many new hadron states were observed in the heavy quarkonia mass region. Most of them do not fit in the quark model expectations, and are called XYZ states. Many such states are located around thresholds of lighter hadrons, and are thus proposed to be hadronic molecules. The most famous example is the X(3872). There are various other explanations including cusp effects. I will show that the near-threshold narrow prominent structures cannot be simply explained by S-wave threshold cusps. I will also discuss their decays and productions in the hadronic molecular picture.
Masayasu Harada Modification of spectrum of heavy-light mesons in nuclear medium I will summarize our recent paper on the modification of spectrum on heavy-light mesons in nuclear medium. References : Phys.Rev. C89 (2014) 068201 & arXiv:1412.2462.
Shoji Hashimoto Simulating 2+1-flavor QCD on fine lattices with Mobius domain-fermions I describe the on-going effort of simulating 2+1-flavor QCD on fine lattices of 1/a=2.4-4.5 GeV. We use the Mobius domain-wall fermion formulation, with which the violation of the Ginsparg-Wilson relation is at the level of a few MeV or below. I report on the simulation status as well as some first physics results.
Tetsuo Hatsuda Photon polarization in heavy ion collisions Production of polarized photon from relativistic heavy ion collision is proposed to be a good measure of the momentum anisotropy of quark-gluon plasma.
Yoichi Ikeda Charmed tetraquarks from lattice QCD We study the candidates of charmed tetra quarks, e.g., Tcc, Tcs, and Zc(3900), from full QCD simulation. We define potentials for the systems on the lattice from which we obtain the spectrum and pole positions. In the presentation, I will explain how to define potentials on the lattice, and our results on the charmed tetraquarks.
Kenta Itahashi Experimental spectroscopy of pionic atoms and eta'-mesic nuclei I will report our recent experimental studies on pionic atoms and eta'-mesic nuclei, including the first production measurement of pionic atom spectra at RIBF and the first pilot experiment for eta' mesic nuclei search at GSI.
Etsuko Itou Quantum entanglement entropy for SU(3) gauge theories I would like to discuss about the applications of quantum entanglement entropy to quantum gauge theories. Quantum entanglement of ground states gives information about a typical correlation length for the quantum systems. The pure Yang-Mills gauge theory or QCD is a confining theory and it is expected to have a mass gap. We expect that the entanglement entropy becomes zero at a finite correlation length and the length would be related with Lambda QCD. It would give a novel order parameter for the quark confinement even if there are dynamical fermions. The other attractive applications is to obtain the entanglement entropy for the conformal gauge theories, for example many flavor QCD. The entanglement entropy is expected to give a novel universal quantity for higher dimensional conformal field theory, since it is related with the central charge in the lower dimensional conformal field theory. In this talk, I would like to review definitions and properties of quantum entanglement entropy and show our preliminary lattice simulation results for the quenched SU(3) gauge theory. This talk is based on the collaboration with K.Nagata, Y.Nakagawa, A.Nakamura and V.I.Zakharov.
David Kaplan Gradient flow for chiral effective theories While dimensional regularization seems to be the ideal choice of regulator for chiral perturbation theory, when nucleons are included there are a number of ways that a mass independent subtraction scheme causes problems. On the other hand, other schemes, such as point splitting or momentum cutoffs are unwieldy or violate chiral symmetry. I will describe work in progress to use gradient flow technology as a regulator for chiral effective theories which explicitly preserves the chiral symmetry. This work is in the continuum, but is inspired by recent lattice applications of gradient flow, and could have applications to lattice calculations of chiral effective nuclear interactions.
Hyun-Chul Kim Transverse structure of the pion and the kaon We report series of recent investigation on the transverse charge and spin structure of the pion and the kaon. Having computed the electromagnetic and tensor form factors of the pion and the kaon, we are able to discuss how the pion and the kaon look like in the transverse plane. We also discuss the stability of the pion and the spin structure of the transition from the kaon to the pion. We discuss possible future works and outlook.
James Lattimer Constraints on the Presence of Quark Matter in Neutron Stars The discovery of neutron stars of 2 solar masses sets strong constraints on the dense matter equation of state. Besides setting lower limits to neutron star radii, it also limits the participation of strangeness in neutron star cores. Nuclear experiments set maximum limits to neutron star radii. These constraints severely limit the quark matter equation of state, whether or not quarks appear in neutron star interiors.
Su Houng Lee Exotics from Heavy Ion Collision We discuss how the structure of multiquark configuration can be studied through its production from heavy ion collision.
Marco Maggiora Highlights on BESIII recent results A selection of the latest BESIII experimental results on hadron spectroscopy will be discussed, with a particular focus on the recent discoveries of the two Zc isospin triplets and on the observation of rare and previously unobserved charmonium states transitions.
Hiroshi Masui RHIC Beam Energy Scan I'm going to review recent experimental results from RHIC Beam Energy Scan. I will discuss what we have learned from current measurements, and what we would expect from future experiments which will be carried out around year 2018 and 2019.
Volker Metag Meson-nucleus interactions studied in photo nuclear experiments Experimental approaches to determine the real and imaginary part of the meson-nucleus potential are described. The experiments have been performed with the Crystal Barrel/TAPS detector at the electron accelerator ELSA (Bonn) and the Crystal Ball/TAPS detector at MAMI (Mainz). Measuring the transparency ratio as well as the excitation function and momentum distribution for photo production of omega and etaprime mesons, the imaginary part of the omega-nucleus potential is found to be larger than the real part. In case of the etaprime meson the opposite is observed. This makes the etaprime meson a good candidate for the search for meson-nucleus bound states while no resolved omega mesic states can be expected. The results are discussed and compared to theoretical predictions. An outlook on future experiments is given.
Kenkichi Miyabayashi Heavy hadron spectroscopy at Belle Studies of many charmonium(-like) and bottomonium(-like) states including exotic candidates performed at Belle experiment are presented. Possible extension to charm baryon(-like) states as well as prospect at Belle II experiment are also discussed.
Colin Morningstar Excited states and scattering phase shifts Progress on computing excited-state energies and scattering phase shifts on 32^3x256 anisotropic lattices at light pion masses of 240 MeV using the stochastic LapH method is described. Current focus is isovector mesons.
Pawel Moskal Interaction of eta and eta-prime mesons with nucleons During last decade large samples of data have been collected on the production of the ground-state mesons in collisions of proton or deuteron beam with hydrogen or deuterium target. These measurements have been performed in the vicinity of the kinematical threshold where only a few partial waves in both initial and final state are expected to contribute to the production process. This simplifies significantly the interpretation of the data, yet still appears to be challenging due to the few particle final state systems with a complex hadronic potential. We will review experiments and phenomenology of the near threshold production of the eta and eta-prime mesons in the proton-proton and proton-deuteron collisions
Hideko Nagahiro Hadron properties at finite density and specroscopies of mesic nuclei Understanding the low-energy spectrum and dynamics of hadrons in the viewpoint of the symmetry of the quantum chromodynamics (QCD) is an important subject in the hadron physics. The study of the meson-nucleus bound systems has been considered to be an important subject in nuclear physics, which must give us important information on partial restoration of the chiral symmetry at finite density as well as the hadron properties in-medium. In this talk, we would like to discuss the properties of the eta and eta'(958) meson-nucleus systems. Although an attractive optical potential is predicted for both systems, the possible mechanisms giving the attractive interaction might be quite different. We would like to show their formation spectra by missing mass spectroscopies and discuss appropriate experimental (kinematical) conditions to observe clearer evidence of the attractive interactions.
Keitaro Nagata Canonical partition functions and Lee-Yang zeros in QCD Recently, QCD at finite temperature and density attracts renewed interests, stimulated by advances in lattice QCD technique for finite density system and a beam energy scan (BES) program, which is an on-going experiment at RHIC to investigate the QCD phase diagram. We will discuss properties of QCD at finite density using a canonical approach, which is based on a fundamental equation describing the relation between canonical and grand canonical partition functions.
Shin Nakamura Effective Temperature of Non-equilibrium Steady States in AdS/CFT Correspondence Non-equilibrium physics is important not only in condensed matter physics but also in quark-hadron physics. In my talk, I will apply the AdS/CFT correspondence to non-equilibrium physics, especially focusing on non-equilibrium steady states beyond the linear response regime. A novel behavior of effective temperatures of non-equilibrium steady states will be reported. I will also try to find a possible connection between the present work and physics in quark-gluon plasma. Refs.: SN. and H. Ooguri, PRD88 (2013) 126003; H. Hoshino and SN., arXiv:1412.1319 [hep-th].
Takashi Nakamura Nuclear matter in neutron stars by experiments and astronomical observatins A neutron star is an extremely dense and compact stellar object which behaves like a gigantic nucleus. Its core density could be high enough to include hyperons and other hadronic matter other than the main component of neutrons. However, the inner structure of a neutron star including the radius-mass relation has not yet been clarified primarily due to a lack of understanding on the Equation of State (EoS) of such matter. Since 2012, we have promoted the project on the nucleonic/hadronic matter by forming a collaboration among leading Japanese experimentalists using J-PARC at KEK and RIBF at RIKEN, atomic physicists simulating fermionic matter by ultra-cold atoms, astrophysicists working on the ASTRO-H project, and theorists in nuclear and astrophysics associating experimental results/astronomical observations to the EoS by theories. In this talk, I will show our current activities and future prospects of this project.
Takashi Nakano Hadron Physics with photon beam at LEPS/LEPS2 TBA
Juan Nieves Hidden charm and bottom molecular states We investigate heavy quark symmetries for heavy light meson-antimeson systems in a contact-range effective field theory. In the SU(3) light flavor limit, the leading order Lagrangian respecting heavy quark spin symmetry contains four independent counter-terms. Neglecting 1/mQ corrections, three of these low energy constants can be determined by theorizing a molecular description of the X(3872) and Zb(10610) states. Thus, we can predict new hadronic molecules, in particular the isovector charmonium partners of the Zb(10610) and the Zb(10650) states. We also discuss hadron molecules composed of a heavy meson and a doubly-heavy baryon, which would be related to the heavy meson-antimeson molecules thanks to the heavy antiquark-diquark symmetry. Finally, we also study the X(3872) -> D0 D0bar pi0 decay, which is not only sensitive to the short distance part of the X(3872) molecular wave function, as the J/Psi pi pi and J/Psi 3pi X(3872) decay modes are, but it is also affected by the long-distance structure of the resonance. Furthermore, this decay might provide some information on the interaction between the D barD charm mesons.
Hiroyuki Noumi Hadron spectroscopy at the J-PARC high-momentum beam line Experimental studies of baryons with heavy quarks utilizing high-resolution, high-momentum secondary beams at J-PARC will be presented. What we can learn through systematic measurements of production cross sections and decay branching ratios as well as level structure of the excited baryons will be dicussed.
Makoto Oka Hadron Spectroscopy from Strange to Charm/Bottom - Effective theories or Lattice? - TBA
Tetsuya Onogi Position space formulation of fermions on hone We study the emergence of massless Dirac fermions in graphene using the postion space formalism of fermions on the honeycomb lattice. We find that there is a hidden chiral flavor symmetry which protects the masslessness.
Eulogio Oset Hadron resonances in finite volume Effective theories with hadron interactions are presented which lead to the generation of resonances. The study is extended to finite volume in order to generate the energy levels in the box. A method is then presented, equivalent to Luescher, which allows one to go from energy levels in the box to phase shifts and bound states. Applications of the method are done for synthetic data to find out the optimal strategies to be followed in lattice simulations. Then the method will also be presented for a recent analysis of real lattice simulation results which show that the KD interaction leads to a bound state, the Ds0*(2317) state, and the KD* leads to the Ds1(2460). We show that the lattice results allow us to determine that the amount of KD or KD* in the way function of these states is about 70%, and discuss which extra lattice results would allow us to pin down the origin of the extra 30%.
David Richards Lattice QCD calculations of the excited-state spectrum, and the low-energy degrees of freedom of QCD TBA
Jacobo Ruiz de Elvira Roy-Steiner equations for pi N scattering Starting from hyperbolic dispersion relations for the invariant amplitudes of pion?nucleon scattering together with crossing symmetry and unitarity, we derive and solve a closed system of integral equations for the partial waves of both the s-channel (piN->pi N) and the t-channel (pipi-> barN N) reaction, called Roy?Steiner equations. Special attention is given to the possible sources of uncertainties and to the obtained sigma_{pi N} term value.
Chris Sachrajda Long Distance Effects in Flavour-Changing Processes TBA
Shoichi Sasaki Heavy quarkonium potential from Bethe-Salpeter wave function on the lattice We have recently proposed a novel method for the determination of the interaquark potential together with quark ``kinetic mass" from the equal-time quark-antiquark Bethe-Salpeter (BS) amplitude in lattice QCD. Our approach allows us to calculate spin-dependent interquark potentials, spin-spin, spin-orbit and tensor potentials, as well. In this talk, we will give a short review of the BS amplitude method on the lattice and present results for both spin-independent and -dependent parts of charmonium potential, which are calculated in 2+1 flavor dynamical lattice QCD using the PACS-CS gauge configurations with a lattice cutoff of 1/a=2.2 GeV. Our simulations are performed with a relativistic heavy-quark action for the charm quark at the lightest pion mass, M_pi = 156(7) MeV, in a spatial volume of (3 fm)^3. We observe that the spin-independent charmonium potential obtained from lattice QCD with almost physical quark masses is quite similar to the Cornell potential used in nonrelativistic potential models. We also present preliminary results for a full set of spin-dependent potentials (spin-spin, spin-orbit and tensor potentials), which is calculated in full lattice QCD for the first time.
Denes Sexty Complex Langevin simulations of non-zero density QCD TBA
Stephen Sharpe Three particle scattering amplitudes from finite volume simulations I describe a formalism that allows one to use knowledge of the spectrum of 2- and 3-particle states in a finite volume (which can, in principle, be obtained from lattice simulations) to determine the infinite-volume 2- and 3-particle scattering amplitudes. This generalizes work by Luscher and others in the two-particle sector.
Stefan Sint Symanzik improvement and the gradient flow in lattice QCD The gradient flow has the potential to become an essential tool for precision physics in lattice QCD. Examples include the definition of reference scales and the determination of alpha_s. I will discuss how to systematically improve the gradient flow a la Symanzik, thereby eliminating the leading lattice artefacts, which are often found to be large. I will present first numerical results using the improved gradient flow and discuss the prospects for the precision determination of alpha_s by the ALPHA collaboration. (This is based on work done in collaboration with Alberto Ramos and with the ALPHA collaboration)
Hiroshi Suzuki Yang-Mills gradient flow and the energy-momentum tensor on the lattice Although the energy-momentum tensor is a fundamental object in field theory, its construction in lattice gauge theory has been an awkward problem because lattice regularization explicitly breaks the translational invariance. In this talk, I show that the Yang-Mills/Wilson gradient flow---its application in lattice gauge theory has intensively been studied in recent years---can be utilized to construct an operator on the lattice that becomes the correctly-normalized conserved energy-momentum tensor automatically in the continuum limit. Explicit construction is given for 4-dimensional gauge theory containing fermions and for the 2-dimensional O(N) non-linear sigma model.
Eric Swanson Cusps, Resonances, and Exotic Charmomia The interplay of threshold cusp and resonance effects in production and decay of X,Y,Z states is presented.
Anthony Thomas From Hadron to Nuclear Structure We review recent advances in hadron structure before turning to the role of the modification of hadron structure in medium in the binding and properties of nuclei.
Antonio Vairo Theory of quarkonium electromagnetic transitions Electromgnetic transitions are the main decay channels for many excited quarkonium states, therefore among the most measured effects in quarkonium physics. Recent experiments have dramatically improved their knowledge and led to discoveries and new precision determinations. The theory of quarkonium electromagnetic transitions relied for long time on potential models. This has changed in the last years with the establishing of effective field theories of QCD for quarkonium. Effective field theories provide model independent determinations. I will review this modern approach and its principal results in the light of some of the latest measurements. I will also compare with recent lattice determinations.
Ubirajara van Kolck Nuclei in a Lattice World Nuclear structure can be predicted from lattice QCD using low-energy effective field theories (EFTs), as I will show in a world with relatively heavy quarks. At distances scales much larger than the inverse pion mass few-nucleon systems are described by an EFT where the leading interactions are contact two- and three-body forces, which explicitly incorporates the universality of loosely bound systems. The solution of the EFT with "ab initio" nuclear methods extends the results of lattice simulations on two- and three-nucleon systems to the relatively large distances that characterize nuclei with many nucleons.
Wolfram Weise Chiral Effective Field Theories and Phases of QCD Recent developments of chiral EFT approaches to the hadronic phase of QCD and the nuclear many-body problem will be summarized. Topics include nuclear chiral thermodynamics and the liquid-gas phase transition, the density and temperature dependence of the chiral condensate, and extrapolations to dense and cold matter in the core of neutron stars. Non-perturbative functional renormalization group methods will be discussed in comparison with in-medium chiral perturbation theory results.
Hartmut Wittig Low-energy precision observables with O(a) improved Wilson fermions I present an overview of calculations employing O(a) improved Wilson in order to study structural properties of the nucleon and to determine the hadronic vacuum polarisation contribution to the muon's anomalous magnetic moment.
Satoshi Yokkaichi Measurement of vector meson in nuclei at J-PARC E16 J-PARC E16 experiment will measure the spectral change of vector mesons in nuclei at High-momentum beam line which is under construction at J-PARC Hadron Hall. Physics prospect and preparation status is presented.
Ross Young Finite volume effects in lattice QCD+QED simulations We report on new spectroscopy calculations in lattice QCD simulations including the dynamical effects of electromagnetism. Particular focus is given to the subtleties associated with the periodic boundary conditions and the long-ranging effects of the QED gauge field.

Contributed talks

Speaker Title Abstract
Sinya Aoki Hadron interactions in lattice QCD I would like to discuss several fundamental issues for the determination of hadron interactions through potentials in lattice QCD (HAL QCD method).
Kenji Araki Analysis of quarkonia at finite temperature from complex Borel sum rules Recently, we proposed a new type of QCD sum rules i.e. the complex Borel sum rules (CBSR) [1]. It has been found that the CBSR is superior to the conventional QCD sum rules from the point of view of the maximum entropy method (MEM) analysis. Specifically, we have demonstrated that our novel method can be used to study the excited states of hadrons. The suppression of quarkonium states (e.g. J/psi and upsilon) is an important signature of the hot matter produced in relativistic heavy-ion collisions at RHIC and LHC. Recently, the behavior of the excited states at finite temperature, which can be different from the ground state, has attracted much attention. The suppression of the charmonium and bottomonium ground states has already been analyzed by conventional QCD sum rules with MEM [2,3]. In this presentation, we report on the results of a reanalysis by CBSR with MEM to investigate the thermal behavior of the quarkonium excited states. [1] K.-J. Araki, K. Ohtani, P. Gubler, and M. Oka, arXiv:1403.6299 (published in PTEP) [2] P. Gubler, K. Morita, and M. Oka, Phys. Rev. Lett. 107, 092003 (2011). [3] K. Suzuki, P. Gubler, K. Morita, and M. Oka, Nucl. Phys. A 897, 28 (2013).
Ahmed Saad Bakry Baryonic strings in Pure Yang-Mills theory and algorithm for noise reduction. We present a study of the signature of the confining Y-bosonic string in the gluonic profile due to a system of three static quarks on the lattice. The analysis of the action density unveils a distribution of a filled-Δ even at large quark separation distances. However, we found that these Δ-shapes are structured out of three Y-shaped string-like flux tubes. The action density width profile returns good fits to a baryonic string model for large quark separation. The revealed nature of the gluonic distribution at finite temperature, where a small change in the string tension occurs, suggests that the observed flux distribution "filled Δ-flux composed of three Y-shaped Gaussian-like tubes" is close to the exact geomtry of the field distribution in static baryon at zero temperature. To probe the low-temperature regime of the quenched QCD. We proposed an algorithm that combines the Luscher?Weiss (LW) multi-level error reduction technique with three-dimensional gauge-field smoothing. The simultaneous application of both link-blocking and path-integral factorization techniques is based on the observation that Monte Carlo updating of the three-dimensional smeared lattices preserves the key features of the stringy physics. Refs: 1-Noise reduction by combining smearing with multi-level integration methods, A. S. Bakry, X. Chen, and P. Zhang, Int.J.Mod.Phys.E23, 1460008 (2014). 2- The Y-stringlike behaviour of the gluonic profile of a static baryon at finite T. (To appear) A. S. Bakry, X. Chen, and P. Zhang 3-Gluonic profile of the static baryon at finite temperature Ahmed S. Bakry, Derek B. Leinweber, Anthony G. Williams, Proceedings of the 29th International Symposium on Lattice Field Theory, Squaw Valley, Lake Tahoe, California, USA; 07/2011
Kadir Utku Can Lattice QCD calculation of electromagnetic form factors of charmed baryons We calculate the electromagnetic form factors of singly and doubly charmed baryons, namely $Sigma_c$ (uuc, ddc), $Xi_{cc}$ (ucc, dcc), $Omega_c$ (ssc) and $Omega_{cc}$ (scc), within the framework of lattice QCD with 2+1 dynamical quarks. As a by product we extract their electric/magnetic charge radii and magnetic moments. We find that these observables are smaller compared to that of proton's. Individual quark sector analysis suggests that we can attribute such a decrease to the existence of the valance charm quark.
Susana Coito Unquenched vector mesons with open beauty Open bottom spectroscopy is still very poorly studied in the experiment [1]. Only two vector resonances have been reported, viz., $B^*$ and $B_s^*$, yet in only a few data. The $B_c^*$ state has never been observed. Several other resonances around 5.72 GeV and 5.83 GeV, respectively with decays to B*pi and B*K, are usually, correspondingly, identified with the axial-vector/pseudovector $B_1$ and $B_{s1}$, from model predictions. An intriguing state is also found at 5.7 GeV with decays to $B^*pi$ and to $Bpi$, the last being a forbidden decay of $B_1$. Moreover, the experimental state at 5.75 with decays both to $Bpi$ and $B^*pi$, is identified with the first $B_2^*$ state. A new resonance was observed recently at CDF [2] around 5.97 GeV, with a P-wave decay to Bpi, near the predicted mass of the $B^*(2S)$, according to several quark model approaches [3]. In this talk, we present results of the first vector recurrences of the open bottom within the unitary nonperturbative Resonance-Spectrum-Expansion model, by coupling the $B^*$ and $B_s^*$ to the respective nearby OZI-allowed decay channels. Similar models have been employed previously to predict the axial-vectors/pseudovectors $B_1$, $B_{s1}$, and $B_{c1}$ [4] and also the scalars $B_0^*$, $B_{s0}^*$, and $B_{c0}^*$ [5]. [1] K.A. Olive et al. (Particle Data Group), Chin. Phys. C 38, 090001 (2014). [2] T. Aaltonen at al. (CDF Collaboration), Phys. Rev. D 90, 012013 (2014). [3] Y. Sun et al., Phys. Rev. D 89, 054026 (2014). [4] E. van Beveren, G. Rupp, Eur. Phys. J. C 32, 493 (2004). [5] E. van Beveren, G. Rupp, arXiv:hep-ph/0312078v1.
Guido Cossu Axial symmetry at finite temperature and lowest modes of the Dirac operator I will discuss the fate of the axial symmetry in the chirally symmetric phase of QCD and the properties of the Dirac operator eigenmodes at these temperatures.
Veljko Dmitrasinovic The Ordering Of Low-Lying Bound States Of Three Identical Particles - Revisited We present the first new results, 25 years after Richard and Taxil's pioneering work, on the ordering of bound states of three identical particles, a problem raised by baryon spectroscopy. We calculate the K < 6 eigen-energies of three-identical-particles states with definite permutation symmetry (i.e. of SU(6) multiplets, for three-quark states) bound by a spin- and momentum-independent three-quark potential in three spatial dimensions. To that end we use the $S_3 \otimes SO(3)_{rot} \subset U(1) \otimes SO(3)_{rot} \subset U(3) \subset O(6)$ chain of algebras to construct all the necessary K < 6 permutation-symmetric hyper-spherical harmonics, as well as the K < 12, L=0 ones, that are necessary to expand the three-body potentials in terms of hyper-spherical harmonics. Our results are general, valid not just for confining potentials, but for spin- and momentum-independent permutation-symmetric potentials that are not necessarily a pairwise sum.
Takahiro Doi Contribution to the Polyakov loop from low-lying Dirac mode in QCD In QCD, the Polyakov loop is an important for quark confinement and the Dirac modes are strongly related to chiral symmetry breaking. We discuss the relation between confinement and chiral symmetry breaking in QCD by using the analytical relation connecting the Polyakov loop and the Dirac modes on the lattice with the odd temporal lattice size. We also perform the numerical lattice QCD analysis beyond the quenched approximation.
Takumi Doi Three-Nucleon Forces from Lattice QCD The determination of three-nucleon forces is one of the most urgent challenges in nuclear physics and astrophysics to understand phenomena as binding energies of nuclei, magic numbers of neutron-rich nuclei and EoS of dense systems relevant to supernovae and the structure of neutron stars. Recently, a first-principles lattice QCD determination of nuclear forces is becoming possible by a novel theoretical method, HAL QCD method, in which Nambu-Bethe-Salpeter (NBS) wave functions are utilized. In my talk, I will present the recent theoretical / numerical development in the lattice QCD study of three-nucleon forces with HAL QCD method.
Akinnobu Dote Investigation of KbarNN resonances with a coupled-channel Complex Scaling Method + Feshbach projection In my talk, I'll report our recent result of a prototype of kaonic nuclei, ``K-pp'', with a coupled-channel Complex Scaling Method (ccCSM). Combining the ccCSM with Feshbach projection method, we can handle a coupled-channel problem effectively as a single-channel problem. By using an energy-dependent chiral SU(3)-based KbarN potential, the K-pp (Jp=0- and T=1/2) is obtained to be shallowly bound with the binding energy of around 20-30 MeV. The mesonic decay width rather depends on the interaction parameters and ansatz; the decay width is ranging from 20 to 65 MeV. In case of Jp=1- state, no three-body KbarNN resonant states are found with a simple calculation. If possible, I'll show a result of application of ccCSM+Feshbach method to the other mesic nuclei such as eta-NN and so on.
Hirotsugu Fujii Complex Langevin and Thimbles in Chiral Random Matrix Model Sampling with the Complex Langevin Equation (CLE) has been attracting renewed interests as a possible method to solve the sign problem appearing in statistical QCD at finite quark chemical potential. Choosing a chiral random matrix model at finite chemical potential as a testing ground, we discuss some problems and modifications of the method. We also consider the CEL sampling of the random matrix model from the viewpoint of Lefshets thimble.
Hidenori Fukaya Extracting the eta-prime meson mass from the gluonic correlators in lattice QCD The eta-prime meson mass is one of the difficult quantities for lattice QCD to evaluate. In this work, we smear the link variables through the Wilson flow and use a purely gluonic operator to reduce the pion's fluctuation to obtain a good signal in the pseudo-scalar flavor singlet channel. We succeed in extracting the eta-prime meson mass on three different types of lattices, which allows us to estimate its continuum and large volume limits.
Sachiko Fukino Short-range part of YcN interaction in the Quark Cluster Model The interaction of hyperons which contain the strange quark has been studied in detail. It is interesting to extend the study to the charmed baryons and to search for their bound states to nucleus. As the basis, it is important to understand the interaction between the charmed baryon Yc and the nucleon N. In this study, we consider the interaction between Yc and N. The phenomenological models of the YcN interaction have been constructed on the basis of the one-boson exchange. However, the short-range parts of the interaction have not been explored well. Here we use the quark cluster model and calculate the short-range part of the YcN interaction by treating the baryons as three-quark clusters. Due to the quark antisymmetrization, we obtain a non-local potential between Yc and N. Comparison of the results to those in the strange baryons will be discussed in this talk.
Ryutaro Fukuda Canonical approach to finite density lattice QCD In lattice QCD, the sign problem hinders us from simulating the path integral at finite density. To overcome this difficulty, we employ so-called canonical approach with Wilson fermions. Using this method, we can calculate the grand canonical partition functions at any valued of the finite baryon chemical potential by the fugacity expansion. We evaluate the fermion determinant through two types of hopping parameter expansion. One is the standard hopping parameter expansion and in the other method we modify the expansion to include exact hopping contributions in 3D space. We discuss the validity of above method and the QCD phase diagram on density and temperature plane.
Koichi Hattori Charmonium spectroscopy in strong magnetic fields by QCD sum rules We address effects of strong magnetic fields on charmonium spectra by using QCD sum rules. We first discuss a general framework of QCD sum rules necessary for investigating any meson spectra in strong magnetic fields, that is, a consistent treatment of mixing effects in external magnetic fields. We then show charmonium spectra from QCD sum rules, and compare them with those from a hadronic effective theory.
Atsushi Hosaka Charmed baryon structure and productions TBA
Tetsuo Hyodo Antikaon-nucleon interaction and Lambda(1405) in chiral SU(3) dynamics TBA
Takumi Iritani Partial restoration of chiral symmetry and modification of non-perturbative properties inside color flux In the presence of color charges in the QCD vacuum, there appears color flux-tube among them, which leads to a linearly rising confining potential. In this talk, we discuss change of non-perturbative QCD properties inside color flux-tube, such as chiral symmetry breaking from lattice QCD. We show that the magnitude of chiral condensate is reduced inside the color flux-tube, which suggests partial restoration of chiral symmetry inside “hadrons.” We also discuss modification of axial and topological charge inside the flux, and effects of color charges in QGP phase.
Ryo Iwami Finite density and temperature phase transitions in QCD with many flavors of Wilson fermions We investigate the phase transitions of (2+Nf)-flavor QCD.It is a system that two light flavors and Nf massive flavors exist.In this system, we can find out 1st order phase transition lines and the critical end point relatively easily.We'd like to discuss the change of lines by including finite density and temperature QCD effect. Performing simulations of 2-flavor QCD with Wilson fermions and using the reweighting method, we calculate probability distribution functions of the many-flavor QCD. Through the shape of the distribution function, we determine the boundary of the first order region in the parameter space of the light quark mass and heavy quark mass and chemical potential. It is found that the light quark mass dependence of the critical mass of heavy quarks is very small in the region we investigated. From the light quark mass dependence, it is even possible to extract the nature of the transition of massless 2-flavor QCD. This study connect the nature of phase transition in the case of massless 2 flavors.
Hiroyuki Kamano Dynamical coupled-channels study of hyperon resonances using anti-kaon induced reactions We develop a dynamical coupled-channels model of K^- p reactions for the purpose of establishing mass spectrum of hyperon resonances and determining the partial wave amplitudes of the elementary anti-kaon-nucleon reactions. The channel space of the model is spanned by the two-body barK N, pi Sigma, pi Lambda, eta Lambda, and K Xi channels as well as the three-body pi pi Lambda and pi bar K N channels that have the quasi-two-body piSigma^* and barK^* N components. The model parameters are fixed by a comprehensive analysis of the available unpolarized and polarized observables of K^- p --> barK N, pi Sigma, pi Lambda, eta Lambda, K Xi reactions from the threshold up to sqrt{s} = 2.1 GeV. In this talk, we report the current status of the comprehensive multichannel analysis of K^-p reactions, and the extracted parameters (pole masses and coupling strengths defined by the residues of the scattering amplitudes at the pole) of hyperon resonances. We also discuss about the role of the reaction dynamics for understanding of various properties of hyperon resonances.
Norihiko Kamata Improved approach of Gradient Flow for thermodynamic quantities in lattice QCD Recently, the novel method to compute the well-defined energy-momentum tensor on the lattice, where the Poincare' invariance is broken explicitely, is proposed by T. Suzuki on the basis of the Yang-Mills gradient flow. This proposal has been applied to study the bulk thermodynamics of SU(3) pure Yang-Mills theory, since the thermal average of the energy-momentum tensor is related to the energy density and the pressure at fixed temparature. The first demonstration with a simple plaquette gauge action done by FlowQCD collaboration was quite successful to reproduce well-known results, which are obtained by the so-called integration method. The results given by the new method, however, are slightly underestimated at the higher temperatures. This fact may suggest that there is some systematic uncertainty during the continuum extrapolation. In this work, we examine possible source of systematic errors in measuring the thermodynamic quantities through the Yang-Mills gradient flow. We then carry out simulations with the RG improved gauge action to expose how large lattice discretization errors they have.
Kazuhiko Kamikado Magnetic susceptibility of a strongly interacting thermal medium Much attention has been paid to the property of strongly interacting medium under strong magnetic field. In this talk, we discuss the effect of the external magnetic field on the thermodynamics of the strongly interacting medium. We analyse the three- and two-flavour quark-meson model using the non-perturbative renormalisation group and evaluate the magnetic susceptibility of the medium. We confirm that at the hadron phase, the medium is diamagnetic due to light pions, while at the QGP phase, it shows paramagnetic behaviour. We also compare our results with the date from lattice QCD and find a reasonable agreement.
Kyoko Katsuyama The nature of the a1(1260) and the spectral function of the a1 from tau decay We study the nature of the low-lying axial vector meson a1(1260). The a1 meson can be a candidate of chiral partner of the rho meson described as a quark-antiquark composite. On the other hand, in coupled-channel approaches based on chiral effective theory, the a1 meson is described as a dynamically generated resonance in pi-rho scattering. Yet, the internal structure of the a1 meson is not well understood. In our study, we focus on the structure of the a1 meson considering the possibilities to have two components of pi-rho composite and quark-antiquark composite. To study this, we investigate the tau decay into three pions, which is dominated by a resonance structure usually ascribed to the a1 meson. Comparing the a1 spectral function extracted from the tau decay measured by the ALEPH collaboration with our calculations in various cases, we discuss possible structure of the a1 meson.
Kouji Kashiwa Investigation of QCD phase structures from imaginary chemical potential region by using effective models At finite imaginary chemical potential, QCD has characteristic properties such as Roberge-Weiss periodicity. Such properties can be used to construct reliable effective models which can be used to investigate the QCD phase structures at finite real chemical potential. In this talk, I will explain which model can be used in this approach and how to extend the model by using information obtained in the imaginary chemical potential region.Also, some applications of the imaginary chemical potential will be presented.
Daiji Kimura A study of tau to nu eta pi pi decay with a chiral Lagrangian including vector mesons We discuss the tau to three hadron decays, tau to nu eta pi pi. In this decay mode, the vector current and the axial current contributions violate the intrinsic parity and the G parity, respectively. The latter contribution is suppressed due to the tiny isospin breaking. We calculate these form factors using a chiral Lagrangian with vector mesons including the effect of isospin breaking and intrinsic parity violation. We also compare our model with Belle data.
Vojtech Krejcirik The effective model for $\bar{K}N$ interactions including the $L=1$ partial wave A coupled-channel model of meson-baryon interactions in the strange sector taking into account both the S and P-wave physics is presented. Its formulation stems from the effective chiral Lagrangian and from the large $N_c$ limit of QCD. The $\Sigma(1385)$ resonance, which dominates the P-wave physics at energies below $\bar{K}N$ threshold, is explicitly accounted for. The presented model aims at a uniform treatment of the $\Lambda(1405)$ and $\Sigma(1385)$ dynamics in the vacuum as well as in the nuclear medium.
Wojciech Krzemien Search for eta-mesic nuclei with WASA-at-COSY We search for an evidence of eta-mesic He with the WASA detector. Two dedicated experiments aiming at studies of 4He-mesic system, were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd-->3Heppi^- and dd-->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus. In May 2014 third complementary experiment was carried out in proton deuteron collisions, aiming at the exploration of the 3He mesic nuclei. In this contribution, the experimental method is described and the current status of the analysis is presented.
Teiji Kunihiro The nature of the sigma meson and the soft modes of the QCD critical points TBA
Xiaohai Liu Influence of threshold effect induced by heavy flavour meson rescattering The lineshape behavior of the cross sections and distributions for the dipion transitions are studied.Couple-channel effects may largely affect the threshold behavior, especially that induced by the couplings between D-wave charmonia and P-wave charmed mesons, taking into account these leading order S-wave couplings will respect heavy quark spin symmetry. Some interesting cusps are obtained, which may have some underlying connections with the XYZ states observed around the open flavor thresholds. We will also discuss the anomalous threshold singularity, which would be used to discriminate coupled-channel effects and genuine resonances
Kenta Miyahara Structure of Lambda(1405) and construction of antikaon-nucleon potential based on chiral unitary approach Recently, the systems with antikaon and nucleons have got a lot of attention because the interaction between these particles is strongly attractive, and leads to interesting phenomena of few-body systems. To analyze such systems, we construct the single-channel local potential for the antikaon-nucleon system from the coupled-channel chiral unitary approach. We establish the construction procedure in which the potential well reproduces the original scattering amplitude, not only on the real axis but also in the complex energy plane. This allows us to study the pole structure of the Lambda(1405) resonance. Applying this procedure to the improved chiral model, we construct the antikaon-nucleon potential constrained by the SIDDHARTA experiment. This potential is used to analyze the spatial structure of Lambda(1405).
Kenji Morita Lambda-Lambda interaction from relativistic heavy ion collisions We investigate Lambda-Lambda correlation function in relativistic heavy ion collisions. The correlation function of two lambda C(Q) is affected by quantum interference (HBT effect for fermions), source function, final state interaction and feed-down effects. Based on recently measured data by STAR collaboration in Au+Au collisions at RHIC, we discuss the role of these ingredients by employing different source models and give constraints on the interaction parameters, scattering length and effective ranges.
Takuya Morozumi Chiral Lagrangian with vector mesons, power counting with chiral breaking We have formulated the systematic power counting for chiral Lagrangian including vector meson. This has been carried out for loop diagrams of Nambu-Goldstone bosons without chiral breaking terms. I will explain how to extend the power counting for the case including chiral breaking terms, and also for the case eta, and phi mesons are included.
Ryou Nagasawa Analyzing non-abelian gauge theory with auxiliary fields Recently, Kaplan proposed an interesting extension of QCD : XQCD (=extended QCD) with bosonic auxiliary fields. While its partition function is kept exactly the same as that of QCD, it is shown that XQCD naturally contains properties of low-energy hadrons. We apply this extension to the two-dimensional QCD in the large N_c limit ('t Hooft model), which is a solvable model. We directly examine the hadronic picture of the 2d XQCD and analyze its renormalization group flow to understand what kind of roles the auxiliary degrees of freedom play in the low energy region.
Satoshi Nakamura Neutrino-induced meson productions We discuss our dynamical coupled-channels (DCC) model for neutrino-nucleon interaction in the resonance region where single- and double-pion productions are dominant. Our DCC model is based on meson-exchange non-resonant mechanisms, and excitaions of nucleon resonances. By solving a scattering equation, we obtain unitary amplitudes for meson productions such as pi N, pi pi N, eta N, K Sigma and K Lambda. The DCC model has been well tested by a large amount of data for meson productions induced by pion, photon and electron. We extend the DCC model to describe the neutrino processes. Developing the axial-current is a crucial part of the extension. We present and discuss results of our calculations for the neutrino-induced meson production cross sections.
Seijiro Nishi Omega_bcc energy spectrum in the Y-string three-body confinement potential The interquark potential is expressed by the confinement term and the one gluon exchange term. According to the Lattice QCD, the confinement potential between among three heavy quarks is not given by the Delta-string type like in the quark-antiquark system but by the Y-string three-body type potential. In our work, we calculated the energy mass spectrum of Omega_bcc baryon in the Y-string potential, the color Coulomb potential and the spin-spin interaction potential using the constituent quark model and the Gaussian Expansion Method.
Shunsuke Ohkoda Spin partners of heavy meson molecules In the heavy quark limit, spin degeneracy emerges in the system of heavy hadrons as a consequence of heavy quark symmetry. We study the heavy meson molecules in the heavy quark limit and clarify their spin structures and spin partners. This study also provides the information about the properties of heavy meson molecules such as the fractions of wavefunctions and the ratios of the productions and decays. The charged bottomonium-like resonances, Zb(10610) and Zb(10650), are discussed from the point of view of the molecule picture.
Akira Ohnishi Neutron star matter EOS in RMF with multi-body couplings One of the current important subjects in neutron star physics is to understand the effect of multi-body (3-body, 4-body, ...) forces. In phenomenological treatments such as RMF, these multi-body forces would appear as multi-body coupling terms such as sigma-sigma-N. We discuss the property of neutron star matter in RMF with multi-body couplings. Coupling constants for nucleonic matter are determined to fit several ab initio calculation results with two-nucleon forces (2NF) and two- and three-nucleon forces (2NF+3NF). Hyperon-meson couplings are given to fit hypernuclear physics information. With this use of ab initio results and phenomenological information, we discuss the appearance / non-appearance of hyperons in the core region of neutron stars.
Keisuke Ohtani Modification of nucleon spectral function in the nuclear medium from QCD sum rules The QCD sum rule method is a powerful tool for studying hadron properties directly from QCD. Recently, the Maximum Entropy Method (MEM) has been applied and is successful in the analysis of the rho meson sum rule. We have applied this analysis method of QCD sum rules to the spectral function of the nucleon[1] and its negative parity excited states in vacuum and have constructed the parity projected nucleon sum rules including the first order alpha_s corrections by using a phase-rotated Gaussian kernel[2]. Both the positive and negative parity spectral function of the nucleon are obtained. We find that the difference between the positive and negative parity spectral function is mainly caused by the chiral condensate. Applying this method to the analyses in nuclear matter, the mass modification of both the positive and negative parity states can be examined. By doing this, we investigate the relation between the masses and partial restoration of chiral symmetry breaking. [1] K. Ohtani, P. Gubler and M. Oka, Eur. Phys. J. A 47, 114 (2011). [2] K. Ohtani, P. Gubler and M. Oka, Phys. Rev. D 87, 034027 (2013).
Sho Ozaki QCD vacuum in strong magnetic fields Recently, much attention has been paid to QCD under strong magnetic fields. It has been recognized that extremely strong magnetic fields are generated in relativistic heavy ion collisions. The magnitude of the magnetic field is thought to reach the QCD scale. Such strong magnetic fields possibly affect QCD vacuum structures and hadron properties. Furthermore, it is a great theoretical advantage that lattice QCD can simulate strongly interacting quark and gluon system in the presence of strong magnetic fields without sign problem. As a first step towards understanding the effect of magnetic fields on QCD vacuum, we analytically derive the Euler-Heisenberg action for QCD+QED at zero and finite temperatures [1]. From the action, we show an anisotropy of the QCD vacuum in strong magnetic fields. The action also show the gluonic magnetic catalysis, an enhancement of the gluon condensate with an increasing magnetic field. These results are consistent with recent lattice observations. At finite temperatures, we find that the magnetic field enhances the explicit breaking of the center symmetry of QCD [2]. This effect would reduce the (pseudo-)critical temperature of deconfinement phase transition, leading to inverse magnetic catalysis observed in current lattice data at finite temperatures [3]. [1] S. Ozaki, PRD89 (2014) 054022 [2] S. Ozaki, T. Arai, K. Hattori and K. Itakura in progress. [3] F. Bruckmann, G. Endrodi and T. G. Kovacs, JHEP 1304 (2013) 112
Hana Saito The chiral condense of the Schwinger model at finite temperature with Matrix Product States Schwinger model is 1+1 dimensional QED model. The model has common features with QCD; chiral symmetry breaking and confinement. In this study, we investigate the chiral symmetry restoration of the 1-flavour Schwinger model at finite temperature with Tensor Network (TN) approach. Recently, it has been pointed out that TN approach is an efficient way to approximate of quantum many body state. We present results of the chiral condense at finite temperature computed with one of TN approaches, called Matrix Product State.
Shuntaro Sakai The eta decay into 3pi in asymmetric nuclear medium and partial restoration of chiral symmetry in nuclear medium We explore how the eta-pi^0 mixing angle and the eta meson decay into pi^+pi^-pi^0 and 3pi^0 are modified in the nuclear medium on the basis of the in-medium chiral effective field theory with the isospin-asymmetry alpha and the total baryon density ho varied, where alpha=delta-rho/rho with delta rho=rho_n-rho_p and rho=rho_n+rho_p. We find that the larger the isospin-asymmetry delta-rho and the smaller the total baryon density rho, the more enhanced the mixing angle. It turns out that the effect of the total baryon denisty on the decay widths overwhelms that coming from the isospin-asymemtry, and the higher rho, the more enhanced the decay widths; the width for the pi^+pi^-pi^0 decay is enhanced with a factor of two to three at the normal density rho_0 with a minor increase due to delta-rho, while that for the 3pi^0 decay shows only a small increase of around 10 percent even at rho_0. We show that the total baryon density dependence of the decay width can be nicely renormalized into the density-dependent pion decay constant f_pi^ast(rho), which decreases as the rho goes high; the density-dependenceof it originates from a low energy constant c_1 and hence the pi-N sigma term. Thus we find that an enhancement of the eta decay into 3pi in the nuclear medium can be another signal of the possible partial restoration of chiral symmetry at finite density.
Chihiro Sasaki Chiral thermodynamics with charm Chiral thermodynamics of charmed mesons is formulated at finite temperature within a $2+1+1$-flavored effective Lagrangian incorporating heavy quark symmetry. The charmed-meson mean fields act as an extra source which breaks the chiral symmetry explicitly. This leads to effective interactions of the light and heavy-light mesons, which depend on temperature. Effective masses of the scalar and pseudoscalar charmed-mesons tend to approach each other as increasing temperature, so that the splitting between the chiral partners is reduced. These chiral splittings turn out to be less sensitive to the light-quark flavors, attributed to the underlying heavy quark symmetry. Consequently, chiral symmetry restoration is more accelerated in the strange charmed-mesons than in the strange light mesons, and this is in striking contrast to the chiral SU(4) result.
Yuichiro Sekiguchi Exploring physics of dense matter using gravitational waves from binary neutron star merger Binary neutron star mergers are quite interesting phenomena in the universe. They are ones of the most promising sources of gravitational waves. The information carried by gravitational waves contain dynamical responses of neutron stars, which could be used to explore the physics of dense matter. In this sense, binary neutron star mergers may be regarded as a cosmological collider or laboratory to explore the fundamental physics. To study binary neutron star mergers, numerical relativity is the most viable approach. Recent advances in this field have yielded a number of important results, such as a possible way to constrain the composition of the neutron star matter. In this talk, starting from brief discussions on the relationship among structure of neutron star, equation of state, and nuclear parameters like symmetry energies, I will review recent developments and discuss future prospects.
Takayasu Sekihara Constraint on K Kbar compositeness of the a0(980) and f0(980) resonances from their mixing intensity Structure of the a0(980) and f0(980) resonances is investigated with the a0(980)-f0(980) mixing intensity from the viewpoint of compositeness, which corresponds to the amount of two-body states composing resonances as well as bound states. For this purpose we establish a relation between the mixing intensity and the K Kbar compositeness for the a0(980) and f0(980) resonances. As a result, a small mixing intensity indicates a small value of the product of the K Kbar compositeness for the a0(980) and f0(980) resonances. Then, combining this relation and the a0(980)-f0(980) mixing intensity recently observed in BES experiments, we find that the statement that both the a0(980) and f0(980) resonances are simultaneously K Kbar molecular states is questionable.
Hyeon-Dong Son Kaon semileptonic transition form factors and the transverse spin density We investigate the Kaon semileptonic decay form factors within the nonlocal chiral quark model from the instanton vacuum. The corresponding transition transverse spin density shows a sizeable distortion, if the quark spin is polarized inside a Kaon due to the non-vanishing transition tensor form factor.
Kei Suzuki Recent progress of QCD sum rules for D meson in extreme environments QCD sum rule is a way to investigate hadron properties based on QCD. Also, mesons with a heavy quark, D and B meson, are known as a probe of extreme conditions such as finite temperature, density and EM fields. In this presentation, I will discuss properties of D meson in such external fields from QCD sum rules. At finite baryon density, masses of D and D bar meson split by interaction with surrounding nuclear matter. On the other hand, in finite magnetic field, D meson mass shifts by magnetic effects such as Landau level and/or mixing with other state.
Takashi Suzuki Extracting the electro-magnetic pion form factor from QCD in a finite volume We consider finite volume effects on the pion form factor in Lattice QCD. Computing the pseudoscalar-vector-pseudoscalar three-point function in a finite box within chiral perturbation theory, we find a way to automatically cancel the dominant effect coming from the zero momentum mode of the pion. Inserting momenta to the correlators, and taking an appropriate ratio of them, we can suppress the finite volume effects to a percent level even in the very vicinity of the chiral limit.
Tatsuyuki Takatsuka Maximum mass of neutron stars with hadron-quark transient core We discuss how neutron stars(NSs) could be massive by including a quark degrees of freedom and ask whether they could be compatible with the two-solar-mass NS observations. We approach the problem phenomenologically by a "3-window model" which divide the equation of state(EOS) into 3 density regime,i.e.,pure hadron matter,hadron-quark transient matter and pure quark matter EOSs,according to the density increase.It is found that NSs as massive as 2-solar-mass can be made possible by a hadron-quark transition in their cores.
Yoshiki K. Tanaka Search for eta' mesic nuclei with (p,d) reaction at GSI We performed a spectroscopic experiment of (p,d) reaction to search for eta' meson-nucleus bound states at GSI. A 2.5 GeV proton beam was employed to produce eta' mesic carbon nuclei in the C(p,d) reaction. A missing mass spectrum around the etaprime emission threshold was obtained by measuring the momenta of the ejectile deuterons using the FRS as a spectrometer. The status of the analysis will be reported. *This experiment was performed in the framework of the Super-FRS collaboration for FAIR.
Kunihiko Terasaki X(3872) –> J/psi pi pi pi as a Three-Step Decay and Related The X(3872) –> J/psi pi pi pi decay is studied as a three-step decay. Experiments have suggested that the three pion state in the decay arises from the omega meson, and it is seen that the omega meson decays into three pions dominantly through a rho meson pole. This implies that the X(3872) –> J/psi pi pi pi decay proceeds as X(3872) –> J/psi omega –> J/psi pi rho –> J/psi pi pi pi. In this way, the decay can be treated as a three-step decay. On the other hand, the pi pi state in the X(3872) –> J/psi pi pi decay arises from rho, as suggested by experiments. Under the assumption that the isospin non-conservation in the decay is caused by the omega-rho mixing, it proceeds as X(3872) –> J/psi omega –> J/psi rho –> J/psi pi pi. Therefore, it can be treated as a two-step decay. The ratio of the resulting rates for the above two decays of X(3872), which has no adjustable parameter, is compared with the measured one.
Akio Tomiya U (1) axial anomaly with chiral fermion at finite temperature We investigate the issue of possible restoration of the axial U(1) symmetry at finite temperature, using lattice simulations with the Mobius domain-wall fermion. In this talk, we focus on the effects of near-zero Dirac eigenmodes, which play a crucial role for both SU(2)xSU(2) chiral symmetry restoration and the restoration/breaking of axial U(1) symmetry. We discuss volume, quark mass and residual violation of the chiral symmetry dependence on the gap in the Dieac spectrum.
Masayuki Wakayama Lattice study of four-quark components of the iso-singlet scalar mesons We study the possible significance of four-quark states in the iso-singlet scalar mesons by a two-flavor full lattice QCD simulations on the 8^3x16 lattice using the improved gauge action and the clover improved Wilson quark action. In particular, for the first time, we evaluate the correlators of tetra-quark and molecular states together with the singly disconnected diagrams. For the computation of the singly disconnected diagram we employ the Z_2-noise method with truncated eigenmode approach. We find that the singly disconnected diagram plays an important role in understanding the tetra-quark and molecular states.
Akira Watanabe Nucleon and photon structure functions at small x in a holographic QCD model We present analyses on the nucleon and photon structure functions at small Bjorken-x in the framework of holographic QCD. First of all, we apply the Pomeron exchange picture to the deep inelastic scattering at small x, and calculate the nucleon structure functions by combining the Pomeron-nucleon coupling obtained via a AdS/QCD model and the wave function of the 5D U(1) vector field with the so-called Brower-Polchinski-Strassler-Tan (BPST) Pomeron exchange kernel. We show that our calculations for F_2^p and F_L^p are consistent with the experimental data measured at HERA. After that, we present recent results on the photon structure functions at small x. In contrast to the nucleon case, we do not need to introduce approximations nor models to describe the incident and target particles for this case. Hence, the model dependence is less than that in the nucleon case, and it may be considered to be a cleaner process to test the BPST kernel. Since two of the three adjustable parameters of the model are fixed in the calculations for the nucleon, we can evaluate the photon structure functions with only a single adjustable parameter. Although presently available experimental data for F_2^\gamma at small x are quite limited, our calculations are consistent with them. Our results presented in this talk will be tested via the experiments at the future linear colliders, e.g., the International Linear Collider.
Junko Yamagata-Sekihara Structure and formation spectra of Dbar meson-nucleus systems We study theoretically the structure and formation of the Dbar meson -nucleus systems to study the Dbar meson in nucleus. The Dbar meson has anti-charm quark and DbarN doesn't have a lower meson-nucleon channel for strong interaction decay. We expect the Dbar mesic nuclear state could be discrete state. We show the calculated formation spectra by (pbar,D) reaction. In addition, we also consider D meson-nucleus systems.
Takeshi Yamazaki Light nuclei from 2+1 flavor lattice QCD We present our calculations in multi-nucleon channels where the nuclear mass numbers are from two to four. The simulations are performed in 2+1 flavor lattice QCD with Iwasaki and non-perturbative improved Wilson quark actions at the lattice spacing of a = 0.09 fm with the pion mass of 0.3 GeV and 0.5 GeV. We will discuss the volume dependence of the energy difference between the ground state and the free nucleons by using the several lattice sizes to distinguish a bound state from attractive scattering state. The pion mass dependence of the energy shift will be discussed using our results and previous results from other groups.
Shigehiro Yasui Charm baryon spectroscopy from heavy quark symmetry Heavy baryons are interesting objects for understand the heavy quark symmetry.We discuss the mass spectroscopy of charm baryons from the heavy quark symmetry and chiral symmetry. Including the finite mass corrections for heavy quark mass expansion, we discuss the transition decay widths by one-pion emission in p-wave from highly excited heavy baryons. We find relations between several channels, which hold at the next-to-leading order. They will provide us with useful information to understand the heavy-quark spin structure in heavy baryons.
Akira Yokota J/psi-bound nuclei and J/psi-nucleon interaction One of the important topics in charmonium$(cc^{bar})$ physics is to study $(cc^{bar})-$nucleon($N$) interaction which is dominated by multiple-gluon exchange. The role of gluon (and therefore QCD) as hadronic interaction can be studied in this system since meson exchange interaction is expected to be OZI suppressed. Another important topic is to discuss the possible existence of $(cc^{bar})-$nucleus bound states due to the weakly attractive nature of the $(cc^{bar})-N$ interaction. This is a novel hadronic state which is bound mainly by gluonic interaction. Precise study of $(cc^{bar})-$nucleus bound states in both theoretical and experimental research could figure out the details of $(cc^{bar})-N$ interaction without $(cc^{bar})-N$ scattering experiment, which is difficult to perform at low energy, as was done for $Lambda-N$ interaction through the spectroscopy of hypernucei. For these purposes, previous researches [1] have studied the $(cc^{bar})-N$ potential and the binding energies of $(cc^{bar})-$nucleus for several nuclei, although the results are not in agreement with each other. Along this line, we study $J/psi-$deuteron, $J/psi-^{4}$He and $J/psi-^{8}$Be systems by solving few-body Schroedinger equation via Gaussian Expansion Method(GEM) [2]. We employ an effective (single-)Gaussian potential for $J/psi-N$ interaction and calculate $J/psi-$nucleus binding energy $B$ for various values of the potential strength. Then we obtain a relation between $B$ and the $J/psi-N$ scattering length $a_{J/psi-N}$. The results show that $a_{J/psi-N} < -0.95, -0.24$ and $-0.16$ fm is needed to form a $J/psi-$deuteron, $^{4}$He and $^{8}$Be bound states, respectively [3, 4]. The current lattice QCD data $a_{J/psi-N} simeq -0.35$ fm [5] corresponds to $B simeq 0.5$ and $2$ MeV for $J/psi-^{4}$He and $J/psi-^{8}$Be, respectively. We have also checked that the results are not sensitive to the form (Gaussian- or Yukawa-type) and the range of the $J/psi-N$ potential [3, 4]. Thus, we conclude that charmonium $J/psi$ will form bound states with nuclei of $A ge 4$, supposing that the current lattice QCD evaluation of $a_{J/psi-N}$ is reliable. In our presentation, we will report more details including density distribution and glue like role of $J/psi$. [1] S. J. Brodsky, et al., Phys. Rev. Lett., 64, (1990) 1011; D. A. Wasson, Phys. Rev. Lett., 67, (1991) 2237; G. F. de Teramond et al., Phys. Rev. D, 58, (1998) 034012; V. B. Belyaev et al., Nucl. Phys. A, 780, (2006) 100. [2] E. Hiyama, Y. Kino and M. Kamimura, Prog. Part. Nucl. Phys., 51, (2003) 223. [3] A. Yokota, E. Hiyama, M. Oka, Prog. Theor. Exp. Phys. (2013), 113D01. [4] A. Yokota, E. Hiyama, M. Oka, Few Body Syst. 55 (2014) 761. [5] T. Kawanai, S. Sasaki, PoS LATTICE (2010), 156 (2010).
Tetsuya Yoshida P-wave heavy baryons with the constituent quark model Spectroscopy of excited baryons with heavy quark(s) is one of the major subject in the hadron experimental facilities, such as J-PARC and GSI. It is very important to give predictions and physics guidelines in advance from theory. Lattice QCD is very successful for the ground states, but it has some difficulty in predicting excited states. Therefore it is necessary to construct a reliable model for the spectroscopy for the heavy baryons. We construct a constituent quark model which is well tuned in the strangeness sector and analyze the excited states of charmed and bottomed baryons. We focus our study to the P-wave excited states and perform a precise calculation. We analyze two characteristic excitation modes, the λ-mode and the ρ-mode. From the analysis, we get information on the structure of heavy baryons, which characterizes the production and decay mechanisms and patterns. Such information should be very useful for experimental identification of these excited states.
Ryo Yoshi-ike Magnetic properties of quark matter in the inhomogeneous chiral phase In the QCD phase diagram, we consider “dual chiral density wave (DCDW)” phase [1] where both scalar and pseudoscalar condensates become spatially inhomogeneous and have the periodic configuration. Here, we study the response of quark matter to a weak external magnetic field to show the spontaneous magnetization in the DCDW phase. In an external magnetic field, the energy spectrum of the lowest Landau level becomes asymmetric about zero and chiral anomaly manifests through this asymmetry [2]. This spectral asymmetry also contributes to the thermodynamic potential by the term proportional to a magnetic field, which is the origin of the spontaneous magnetization in the DCDW phase. Furthermore, using the generalized Ginzburg-Landau expansion [3], we discuss the property of the phase transitions around the new critical point, Lifshitz point. References [1] E. Nakano, T. Tatsumi, Phys. Rev. D 71, 114006 (2005) [2] T. Tatsumi, K. Nishiyama, S. Karasawa, arXiv:1405.2155 [3] D. Nickel, Phys. Rev. Let. 103, 072301 (2009)
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