Hadron Spectroscopy Cafe

これまでのHadron Spectroscopy Cafe

第20回 Modern approaches to delineate hyperon interactions in nuclear matter: chiral EFT and femtoscopy

日時
7 May（Wed.）2025 13:30-17:00

場所
RIKEN Main Research Building (4th floor), Room 435-437 (Access: indexed as C01) & オンライン(zoom)のハイブリッド形式

Michio Kohno (RCNP) 13:30-15:00
"Properties of hyperons in nuclear matter with baryon-baryon interactions of chiral effective field theory"

Abstract: The study of hypernuclei, in which hyperons are bound to nuclei, is a long-standing field of nuclear physics. Nevertheless, there are many uncertainties in the description of the interaction between hyperons and nucleons/nuclei. In recent years, significant progress has been made in the observation of astronomical nuclear phenomena, symbolized by the detection of gravitational waves. It has become evident that the appearance of hyperons in neutron star matter, as predicted by the conventional understanding of hypernuclear research, is inconsistent with the observed data. It is apparent that the appearance of hyperons can be avoided by the introduction of a strong repulsive three-body force. However, this does not imply that the neutron star matter is understood from a microscopic point of view. In order to advance our understanding of the nature of hyperons in the nuclear medium, it is desirable to establish the interaction on the basis of a modern theoretical description of the two-body and three-body interactions and rigorous calculations of few-body hyper-nuclei based on this description, and to conduct research to link this to an understanding of neutron star matter. The seminar begins with a concise overview of the concepts of the construction of baryon interactions by chiral effective field theory and three-body interactions. The properties of the hyperon-nucleon interactions in the nuclear medium are then discussed.

Discussion Time 15:00-15:30

Yuki Kamiya (Tohoku U.) 15:30-17:00
"Determination of hadron interaction with femtoscopy"

Abstract: The two-particle momentum correlation function from high-energy nuclear collisions is a powerful tool to study hadron-hadron interaction. Because this observable is sensitive to the low-energy interaction, it is useful to elucidate the nature of the near-threshold resonances and the underlying mechanism of the interaction. Femtoscopic analysis has recently been extended beyond the study of interactions in strange systems, with applications now beginning to include charm systems and those involving three-body effects.
Theoretically, correlation functions can be calculated based on the hadron emission source and the scattering wave function. By providing the former as input, the latter can be extracted. Since the hadron source depends on the setup of the collision experiment, it is essential to determine an appropriate source function. At the same time, employing various sources allows us to investigate the source dependence of correlations, thereby enabling a more detailed study of hadronic interactions. The wave function also exhibits prominent features such as coupled-channel effects and threshold cusps, which must be properly treated—especially compared to conventional scattering experiments. Furthermore, for hadron pairs with Coulomb charge, it is well known that Coulomb interactions must be treated without approximation.
In this talk, I will begin with systems like K^-p, whose interactions are relatively well understood, and then introduce the current status of femtoscopic studies in poorly understood systems, such as those involving charms. Through this, I will discuss how detailed information on resonances and interaction can be extracted and identified from experimental data.

第19回 Complex scaling method: principles and applications

日時
17 May（Fri.）2024 13:30-17:00

場所
Nagoya University Higashiyama Campus, E and S building Room 635 (ES635) (Access: indexed as C2④) & オンライン(zoom)のハイブリッド形式

Takayuki Myo (Osaka Institute of Technology (OIT))
"Physics of unbound light nuclei with complex scaling"

Abstract: Complex scaling is widely used in various physics fields to describe resonances with complex energy eigenstates, which are based on the non-Hermitian quantum mechanics. In this talk, we would like to discuss the following two topics.

"Lecture 1: Principles" 13:30-15:00
Basic properties of the complex scaling in the description of the unbound states are discussed. We present the applications of the complex scaling not only to the resonance spectroscopy, but also to the scattering problem, which is treated by using the Green’s function with complex scaling. We also explain the technical aspect of the complex scaling for the numerical calculations such as the eigenvalue problem.

Discussion Time 15:00-15:30

"Lecture 2: Applications" 15:30-17:00
The unbound phenomena of light nuclei are studied with complex scaling in the few-body cluster model. We focus on many-body resonant and continuum states observed in light proton-rich and neutron-rich nuclei. We discuss the roles of resonant and continuum contributions in the strength functions above the threshold energy of many-particle emission.

第18回 Quark-Hadron dynamics in cold dense matter

日時
21 September（Thu.）2023 13:00-16:30

場所
Tokyo Institute of Technology Ookayama Campus, Main Building M-123 (Access) (Lecture room)
& オンライン(zoom)のハイブリッド形式

Toru Kojo (Tohoku U.) 13:00-14:30
"Quark substructure of hadrons and equations of state in dense QCD"

Abstract: Recent neutron star observations indicate the QCD equation of state should show rapid soft-to-stiff evolution of the stiffness. Such rapid stiffening does not naturally occur in purely nucleonic descriptions whose stiffening rely on many-body forces. I argue that the quark substructure of baryons plays important roles already at density slightly above the nuclear saturation density, certainly before the baryons begin to overlap. The key concept is the ``quark saturation’’: quarks cannot occupy states with the probability greater than 1. The density for quark states to get saturated is sensitive to quark wavefunctions in baryons. The possible resolution of the hyperon puzzle is also discussed in light of quark descriptions. The concepts of quarkyonic matter are also briefly introduced.

Discussion Time 14:30-15:00

Etsuko Itou (YITP, Kyoto U.) 15:00-16:30
"Speed of Sound beyond the conformal bound in Dense Two-Color QCD - Lattice Simulation Results -"

Abstract: We obtain the equation of state (EoS) for two-color QCD at low temperature and high density from the lattice Monte Carlo simulation. Two-color QCD is a good toy model of real three-color QCD. The advantage to study this model is that the sign problem is absent even in a finite density regime because of the pseudo-reality of quark field. We find that the speed of sound exceeds the conformal bound (c_s^2/c^2=1/3) after BEC-BCS crossover in the superfluid phase. Such an excess of the sound velocity is previously unknown from any lattice calculations for QCD-like theories. This finding might have a possible relevance to the EoS of neutron star matter revealed by recent measurements of neutron star masses and radii. This talk is based on PTEP 2022 (2022) 11, 111B01 (e-Print: 2207.01253).

第17回 Pionic atom experiments and chiral symmetry restoration in nuclei

日時
6 February（Mon.）2023 13:00-16:30

場所
Tokyo Institute of Technology Ookayama Campus, Lecture Theatre (No.17) (Access)
東京工業大学大岡山キャンパス　レクチャーシアター (アクセス)

Satoru Hirenzaki (Nara Women's U.) 13:00-14:30
"Theoretical study of Deeply Bound Pionic Atoms"

Abstract: In this seminar, a brief review of the study of the deeply bound pionic atoms and an introduction to the physics of the mesonic atoms and mesonic nuclei will be given. In the meson–nucleus bound systems, the real meson exists inside and/or very close to the surface of the nucleus. The strong interaction plays the dominant role in the systems and determines the structures and properties of the mesonic atoms and mesonic nuclei. We will begin with the introductory remarks on the basic physics of the meson–nucleus bound systems, then, give the explanation of the theoretical studies of the structure and formation of the deeply bound pionic atoms. We will also mention the investigation of the strong interaction symmetry at finite density by the meson–nucleus bound systems.

Discussion Time 14:30-15:00

Kenta Itahashi (RIKEN) 15:00-16:30
"Pionic atom unveils hidden structure of QCD vacuum"

Abstract: In this seminar, the spectroscopy of pionic atoms will be discussed in terms of an experimental approach to understanding the low-energy sector of the QCD. The non-perturbative nature requires the existence of non-trivial structures, such as qbar q in the vacuum. In the spectroscopy, pionic Sn 121 atom was measured, and the pion-nucleus interaction was deduced with high accuracy. The deduced interaction is found to be modified in the nuclear matter due to the wavefunction renormalization of the medium effect. We deduced < qbar q> in the nuclear medium based on the accurate experimental data and the theoretical works. We also discuss future projects for pionic unstable nuclei.

第16回 Recent hot topics and future prospects of hadron experiments at J-PARC

日時
20 July（Wed.）2022 13:00-16:30

場所
Tokyo Institute of Technology Ookayama Campus, Lecture Theatre (No.17) (Access)
東京工業大学大岡山キャンパス　レクチャーシアター (アクセス)
& オンライン(zoom)のハイブリッド形式

Hiroyuki Noumi (RCNP, KEK) 13:00-14:30
"Study of Lambda(1405) resonance via kaon-induced reactions on deuteron at J-PARC"

Abstract: Lambda(1405) is a well-known hyperon resonance with the spin-parity of 1/2-, located just below the antikaon-nucleon (KbarN) mass threshold. It is known that its mass and width is difficult to explain by a simple quark model. There are long-standing arguments on a meson-baryon aspect of the Lambda(1405) resonance. In particular, pole structure of Lambda(1405) has been intensively discussed. Since Lambda(1405) is located below the KbarN mass threshold, its pole position is deduced based on the available Kaonic hydrogen and KbarN scattering cross sections above the KbarN mass threshold. It would be useful if the KbarN scattering cross sections are measured below the KbarN threshold. Is it possible? The answer is yes. We proposed and carried out an experiment to measure spectral shapes of Lambda(1405) in the d(K-,n)piSigma reactions at J-PARC. In this reaction, a neutron is knocked out from a deuteron by an incident K- and a recoiled Kbar reacts with a residual nucleon decaying into a pion (pi) and a Sigma hyperon. Since the recoiled Kbar and/or the residual nucleon are so-called off-shell particles, the KbarN scattering can take place even below the KbarN mass threshold. In the case of the knocked-out neutron emitted at a forward angle, the recoiled kaon momentum is as low as about 250 MeV/c. This reaction is expected that an S-wave KbarN scattering is dominant. We successfully measured pi-Sigma mass spectra below and above the KbarN mass threshold. We could demonstrate that the measured spectra are well described by the above-mentioned two-step reaction. We will discuss KbarN scattering amplitude and its resonance pole deduced from the measured spectra.

Discussion Time 14:30-15:00

Kotaro Shirotori (RCNP) 15:00-16:30
"Spectroscopic experiments of charmed and strange baryons at J-PARC"

Abstract: Hadrons are composite particles of interacting quarks and gluons. Recently, quantum chromodynamics (QCD) has successfully described the interaction of quarks and gluons. However, the dynamics of low-energy QCD, such as hadron formation, has not been clearly explained because perturbation theory does not work in the low-energy regime. Understanding hadron formation is one of the fundamental goals of hadron physics. Recent experimental results have revealed the rich nature of the excited states of hadrons. To understand these properties, it is necessary to investigate the effective degrees of freedom of hadrons beyond the ordinary constructive quark model. Diquark correlation and hadronic molecule can be new effective degrees of freedom for describing hadronic structures. Spectroscopic observations of charmed and strange baryons can provide a unique opportunity to study diquark correlation. Systematic studies of charmed and strange baryons are expected to reveal effective degrees of freedom for describing hadron structures. The hadron experimental facility at J-PARC aims at revealing hadron structures using the world's most intense meson beam. The J-PARC high-intensity and high-momentum beams can provide many opportunities to investigate the structure of hadrons, in which charm and strange quarks play an important role. High-momentum beam line, called the π20 beam line, is under construction at J-PARC, and the charmed baryon spectroscopy experiment (E50) is planned. In the future, the Hadron Experimental Facility are extended to include beam lines with special capabilities. A dedicated high-momentum beam line called the K10 beam line, which can provide separated K- up to 10 GeV/c, is planned to be constructed. Hadron beams are an essential tool for studying the excited states of charmed and strange baryons. We promote important research in hadron physics at J-PARC.

第15回 Hadron interactions and Exotics in Heavy Ion collisions

日時
10 Jan（Fri.）2020 13:30-17:00

場所
Tokyo Institute of Technology Ookayama Campus, Main Building Room 345 (Access)
東京工業大学大岡山キャンパス　本館３階理学院第二会議室 (345号室) (アクセス)

Hideki Hamagaki (IIST, Nagasaki Institute of Applied Science) 13:30-15:00
"Study of hadron interactions and exotic hadrons in the ALICE experiment at CERN LHC -- present and near future --"

Abstract: Hadronic collisions, that is, pp, pA and AA collisions, at high energy turned out to be a powerful tool to study interactions between hadrons including unstable ones and to search for exotic hadrons. In the ALICE experiment at CERN LHC, hadron interactions have been investigated mainly using the femtoscopy technique. I will overview the current status of studies performed at the ALICE experiment. The ALICE experiment is making extensive upgrade, during the currently on-going two-year LHC shutdown period. When completed in a year or so, we will be able to take data with the significantly higher rate. I will briefly describe the ALICE upgrade, and will present about possible hadron physics programs with the upgraded ALICE.

Tea Time 15:00-15:30

Akira Ohnishi (YITP, Kyoto University) 15:30-17:00
"Hadron-hadron correlation and interaction from high-energy nuclear collisions"

Abstract: Hadrons produced in high-energy nuclear collisions interact with each other in the final stage, and correlations among hadrons are produced from the quantum statistics and the hadron-hadron interaction. Thus the correlation can be regarded as the scattering via the final state interaction. Aiming at getting information on interactions, hadron-hadron correlations have been recently measured for various pairs including ΛΛ [1], Ω^- p [2], Ξ^- p [3], K^- p [4], and pΣ⁰ [5]. In this presentation, we report the results [6,7] of analyzing these data by using interactions proposed so far. In addition to the diagonal matrix element of the potential, the coupled channels effects are found to be important for systems with strong channel coupling such as K^- p [7,8]. We also discuss the existence of hadronic molecule states.

[1] L. Adamczyk et al. (STAR), Phys. Rev. Lett. 114, 022301 (2015); S. Acharya et al. (ALICE), Phys. Rev. C 99, 024001 (2019);
[2] J. Adam et al. (STAR), Phys. Lett. B 790, 490 (2019).
[3] S. Acharya et al. (ALICE), Phys. Rev. Lett. 123, 112002 (2019).
[4] S. Acharya et al. (ALICE), arXiv:1905.13470 [nucl-ex].
[5] S. Acharya et al. (ALICE), arXiv:1910.14407 [nucl-ex].
[6] K. Morita, T. Furumoto, and A. Ohnishi, Phys. Rev. C 91, 024916 (2015); A. Ohnishi, K. Morita, K. Miyahara, and T. Hyodo, Nucl. Phys. A 954, 294 (2016); K. Morita, A. Ohnishi, F. Etminan, and T. Hatsuda, Phys. Rev. C 94, 031901 (2016); K. Morita, S. Gongyo, T. Hatsuda, T. Hyodo, Y. Kamiya, A. Ohnishi, Phys. Rev. C, to appear [arXiv:1908.05414 [nucl-th]]; T. Hatsuda, K. Morita, A. Ohnishi, and K. Sasaki, Nucl. Phys. A 967, 856 (2017);
[7] Y. Kamiya, T. Hyodo, K. Morita, A. Ohnishi and W. Weise, arXiv:1911.01041 [nucl-th].
[8] J. Haidenbauer, Nucl. Phys. A 981, 1 (2019).

第14回 KbarNN at J-PARC

日時
27 May（Mon.）2019 13:30-17:00

場所
Tokyo Institute of Technology Ookayama Campus, Main Building Room 345 (Access)
東京工業大学大岡山キャンパス　本館３階理学院第二会議室 (345号室) (アクセス)

Takumi Yamaga (RIKEN) 13:30-15:00
"Experimental study of kaonic nucleus with anti-kaon beam at J-PARC"

Abstract: Kaonic nucleus is a bound system composed of an anti-kaon and nucleus. Its unique properties are not only a meson being a constituent but also larger binding energy and higher density compared to normal nucleus. However, experimental studies have not established even its existence so far, even for the simplest system of the KbarNN bound state. We have performed an experiment to search for KbarNN by using anti-kaon beam at J-PARC. The result supports the existence of KbarNN whose binding energy and decay width are consistent with theoretical prediction. This observation motivates us to perform the next experiment to search for other kaonic nuclei.

Tea Time 15:00-15:30

Takayasu Sekihara (RCNP, Osaka Univ.) 15:30-17:00
"What can we learn about the "Kbar N N" from the J-PARC E15 peak?
-- Relation between the Lambda p invariant mass spectrum and "Kbar N N" --"

Abstract: In the J-PARC E15 experiment, the Lambda p invariant mass spectrum was measured in the K^- ³He → Λ p n reaction to search for the so-called "Kbar N N" quasi-bound state. As a result, a peak structure was found just below the K^- p p threshold energy. This peak may be a signal of the Kbar N N quasi-bound state. Our question is whether this peak is really a signal of the Kbar N N quasi-bound state or not. Then, what properties of the Kbar N N quasi-bound state can be extracted from the peak structure? To answer these questions, we calculate both the structure of the Kbar N N quasi-bound state and reaction of the K^- ³He → Λ p n on the same footing. In this talk I report our theoretical analysis.

第13回 from Quarks to Hadron

日時
28 Nov.（Wed）2018 13:00-16:30

場所
KEK Tokai campus Tokai 1st building, Room 115 Place

Veljko Dmitrasinovic (Univ. of Belgrade) 13:00-14:30
"Application of Hyperspherical Three-Body Variables to Lattice QCD Data: Is the Three-Quark Confining Potential Y-string or Δ-string?"

Abstract: We analyze the recent lattice QCD results by Koma & Koma, as well as the old ones by Takahashi et al. in terms of hyper-spherical three-body coordinates with a view to the interpretation of lattice data in terms of a string model, either Δ or Y-string. We show that the presently extant data supports neither the Δ nor the Y-string. Some comments about the (numerical) error analysis will be made. We also discuss other possible string-like models: (a) the "barycentric Y-string"; (b) an "arbitrary triangle-center Y-string" configuration. Possible combinations of two or more string configurations are discussed. We suggest specific sets of lattice configurations, for future computations, that allow a simpler discrimination of various string potentials.

Tea Time 14:30-15:00

Hyun-Chul Kim (Inha Univ.) 15:00-16:30
"Chiral quark-soliton model, a pion mean-field approach for the structure of baryons"

Abstract: The chiral quark-soliton model is a quantum-field theoretic pion mean-field approach. The model provides a unifying way of describing both the light and heavy baryons. I will explain the concept and techniques of the chiral quark soliton model, review a series of recent works on heavy baryons and propose several future directions based on it.

第１２回いまさらエキゾチックハドロン？

日時
2018年1月27日（土）13:30- （お茶の時間を含む）

場所
東京工業大学大岡山キャンパス本館156号室場所

瀧澤誠 (昭和薬科大学)
"エキゾチックチャーム・ボトム中間子の最新実験結果とその考察"

竹内幸子 (日本社会事業大学)
"qqbar-QQbar systems by a quark hadron hybrid model"

宮本朋和 (東工大)
"A case for the hybrid interpretation of Y(4260)"

安井繁宏 (東工大)
"励起したチャーモニウムからの2パイオン放出崩壊"

第１１回離散から連続へ！グラディエントフローの基礎から発展まで

日時
2017年7月10日（月）13:30-16:00 （お茶の時間を含む）

場所
東京工業大学大岡山キャンパス本館156号室場所

北沢正清 (阪大)
"gradient flowを用いた格子QCD数値解析"

アブストラクト：格子QCD数値解析は、QCDの非摂動的性質を第一原理的に調べるための重要な研究手段である。近年、gradient flowと呼ばれる場の連続変換が格子QCD数値解析に導入され、様々な問題に応用されてきた。本講演では、gradient flowとは何者なのか、またなぜ様々な解析において有効なのかを説明した後、最近の応用例を紹介する。特に、gradient flowを用いて格子上のエネルギー運動量テンソルを定義し、熱力学量などの物理量を測定する研究に関する最近の進展を詳しく報告したい。

(*) 終了時間は前後する可能性があります。

第１０回高密度物質のフェルミ面が織りなす空間デザイン

日時
2017年5月31日（水）13:30-16:00 （お茶の時間を含む）

場所
東京工業大学大岡山キャンパス本館155B号室場所

巽敏隆 (京大)
"核子・クォーク多体系における非一様相転移とネスティング効果"

アブストラクト：核物質やクォーク物質では多様な空間的非一様構造の可能性が議論され、コンパクト星の現象や高エネルギー重イオン反応などの現象への意義が議論されている。 π中間子凝縮や非一様カイラル凝縮はその典型例である。これらの非一様構造の出現は粒子間の相互作用の特徴・詳細によるが、多体系の物理としてはフェルミ面の存在が重要である。ここではネスティング効果に注目して非一様構造の出現を考察する。また、媒質中でのカイラル対称性の実現の観点や磁場中での超伝導で現れるFFLO状態との関連等についても言及する。

(*) 終了時間は前後する可能性があります。

第９回 Quest for H-dibaryons -experiments, phenomenology, effective theory and lattice QCD-

日時
2017年1月27日（金）13:00-17:00 (14:30-15:00 Tea Time)

場所
東京工業大学大岡山キャンパス本館117号室場所

M. Oka (TiTech) 13:00-13:45
"What is the H-dibaryon?" (Overview)

J.K. Ahn (Korea Univ.) 13:45-14:30
"Hunting the H-dibaryon in the $(K^-,K^+)$ reaction at J-PARC"

Abstract: A recent claim from the LHCb collaboration on the observation of two hidden-charm pentaquark states revives hopes for experimental discoveries of other multiquark baryonic states such as the H-dibaryon with a 6-quark ($uuddss$) configuration. Recent theoretical predictions for the mass of H-dibaryon pointing to the mass region near $\Lambda\Lambda$ threshold also encourage experimental searches. A dedicated experiment (J-PARC E42) has been proposed to search for the H-dibaryon in the bound and unbound mass regions near $\Lambda\Lambda$ threshold. The experiment is designed to measure production of $\Lambda p\pi^-$, $\Lambda\Lambda$ and $\Xi^-p$ systems in the $^{12}$C$(K^-,K^+)$ reaction with a 1-MeV mass resolution. A new large-acceptance spectrometer (Hyperon Spectrometer) consisting of a superconducting dipole magnet and a time projection chamber is now under commissioning. The current status of the J-PARC E42 experiment will be presented.

T. Hyodo (YITP) 15:00-15:45
"Quark-mass dependence of the H dibaryon in Lambda Lambda\CID{1}\CID{1} scattering"

Abstract: We study the quark mass dependence of the H dibaryon in the strangeness S = −2 baryon-baryon scattering. A low-energy effective field theory is used to describe the coupled-channel scattering, in which the quark mass dependence is incorporated so as to reproduce the lattice QCD data by the HAL QCD collaboration in the SU(3) limit. We point out the existence of the Castillejo-Dalitz-Dyson pole in the \CID{1}\CID{1}Lambda Lambda scattering amplitude below the threshold in the SU(3) limit, which may cause the Ramsauer-Townsend effect near the Xi N\CID{1} threshold at the physical point. The H dibaryon is unbound at the physical point, and a resonance appears just below the Xi N\CID{1} threshold. As a consequence of the coupled-channel dynamics, the pole associated with the resonance is not continuously connected to the bound state in the SU(3) limit. Through the extrapolation in quark masses, we show that the unitary limit of the Lambda Lambda\CID{1}\CID{1} scattering is achieved between the physical point and the SU(3) limit. We discuss the possible realization of the “H matter” in the unphysical quark mass region.

K. Sasaki (YITP) 15:45-16:30
"Lattice QCD studies on H-dibaryon state"

Abstract: Baryon interactions play an essential role to understand nuclear phenomena. The determination of baryon interactions based on the fundamental theory, QCD, is one of the most challenging issue in nuclear physics. In this talk, I review the theoretical formulation, HAL QCD method, to obtain baryon forces from the Nambu-Bethe-Salpeter (NBS) four-point correlators measured on the lattice. By using the method, I will show the results of baryon interactions in the H-dibaryon channel and discuss the possibility of dibaryon formations.

(*) 終了時間は前後する可能性があります。

第８回ハドロンの中のハドロン -粒子の"複合性"とは何か？-

日時
2016年11月12日（土）13:30-17:00 (途中休憩を含む)

場所
東京工業大学大岡山キャンパス本館156号室場所

永廣秀子 (奈良女子大学) 13:30-15:00
"Elementarity of composite systems"

Abstract: The question of "elementarity" of the dynamically generated states has been studied by using the wave function renormalization constant Z. In this talk, we show that the renormalization constant Z can take any value, even Z=0, for the state dynamically generated by an energy-dependent interaction like the Weinberg-Tomozawa (WT) term, as in the case for a bound state by an energy-independent interaction. We show that it is possible to construct a "Yukawa model" which gives the completely equivalent scattering amplitude to the one obtained by the WT-type interaction, by letting the bare mass and the bare coupling of the fictitious elementary particle infinite, and as a result, the model gives Z=0 for the state.
References: H.Nagahiro, A. Hosaka, PRC88(2013)055203. H.Nagahiro, A. Hosaka, PRC90(2014)065201.

関原隆泰 (原研先端基礎研究センター) 15:30-17:00
"Two-body wave functions, compositeness, and the internal structure of dynamically generated resonances"

Abstract: エキゾチックハドロンとは、通常の qqq (バリオン) や q qbar (メソン) のクォーク配位とは異なる構造を持つハドロンである。エキゾチックハドロンを発見しその内部構造を明らかにする事は、ハドロン物理において最も重要なテーマの一つである。近年、ハドロン分子構造を見分ける為に、複合性 (compositeness) という量が議論されている。これは、興味あるハドロンの 2 体分子状態 (メソン-メソンやメソン-バリオンなど) 波動関数のノルムで定義され、全波動関数の規格化 (=1) に対する分子状態の寄与を与える。本セミナーでは、ハドロン-ハドロン散乱振幅における共鳴極の位置と留数から波動関数及び複合性を引き出す手法を紹介する。そして、カイラル有効模型を用いて、Λ(1405)、N(1535) や N(1650) といった、いわゆる動的に生成される (dynamically generated) ハドロン共鳴状態の複合性を評価し、それらの内部構造をハドロン分子状態の観点から議論する。

(*) 終了時間は前後する可能性があります。

第７回 To talk about charm pentauqark

日時
2016年5月27日（金）14:00-16:30 (途中休憩を含む)

場所
東京工業大学大岡山キャンパス本館345号室（第二会議室）場所

Xiao-Hai Liu (Tokyo Tech.) 14:00-15:00
"Understanding the nature of heavy pentaquarks and searching for them in pion induced reactions"

Abstract: The LHCb collaborations recently reported the observations of two resonance-like structures, which could be the long-searching-for pentaquark states. When studying these heavy pentaquark candidates, usually one will confront two issues, i.e., what their underlying structures are and how to search for them in experiments. We indicated that these resonance-like peaks may be resulted from some kinematic threshold effects, in particular the triangle singularity mechanism. The triangle singularity mechanism is a highly process-dependent mechanism, which is very different from other dynamic mechanisms. This may bring ambiguities on our understanding of the nature of those exotic states. We therefore needs different kinds of processes to check this mechanism. The piN scattering into J/psi-pion-proton could be a promising reaction to search for the heavy pentaquarks or the effects induced by the triangle singularity mechanism. The forthcoming J-PARC pion-induced experiment may offer us a good opportunity to check different kinematic or dynamic mechanisms and clarify the ambiguities.

Sachiko Takeuchi (Japan College of Social Work) 15:30-16:30
"ccbar pentaquarks by a quark model"

Abstract: Recent LHCb experiments show us that there are two resonances in the N-J/Psi channel, whose spin and parity are most probably (3/2^- 5/2⁺). In this work, we will show that there is a state which gains a large attraction from the color-magnetic interaction in the uudccbar I(J^P)=1/2(3/2^-) channel, which appears as a resonance in the Lambda_c Dbar* channel, when one employs a quark model. We also found that there is an equally or more attractive state in the channel with strangeness, udsccbar, I(J^P)=0(1/2^-).

(*) 終了時間は前後する可能性があります。

第６回格子QCDで見るクォーコニウムの中身 -クォーク間ポテンシャルの本当の姿-

日時
2015年12月4日（金）14:00-17:00 （お茶の時間を含む）

場所
東京工業大学大岡山キャンパス本館H117号室場所

佐々木勝一 (東北大)
"Potential description of charmonium and charmed-strange mesons from lattice QCD"

アブストラクト：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 interquark potentials for the charmonium and charmed-strange mesons, 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 with almost physical quark masses. The charmonium potentials are obtained from the BS wave function of 1S charmonia (η_c and J/ψ mesons), while the charmed-strange potential are calculated from the D_s and D*_s heavy-light mesons. We then use resulting potentials and quark masses as purely theoretical inputs so as to solve the nonrelativistic Schrodinger equation for calculating accessible energy levels of charmonium and charmed-strange mesons without unknown parameters. The resultant spectra below the DDbar and DK thresholds excellently agree with well-established experimental data. In addition, we will discuss validity of the potential model description.

(*) 終了時間は前後する可能性があります。

第５回チャーム原子核の"魅力"とは何か？

日時
2015年8月28日（金）14:00-16:00

場所
東京工業大学大岡山キャンパス本館155B号室場所

肥山詠美子 (理研) 14:00-15:30
"軽いストレンジネス原子核とチャーム原子核の構造と結合相互作用"

アブストラクト：シングルΛハイパー核の世界では、_Λ³H, _Λ⁴H, _Λ⁴HeではΛN-ΣN結合の重要性が指摘されており、過去に結合相互作用を取入れた構造計算がされてきた。チャーム原子核についても、近年、Λ_c-N相互作用についてΛ_cN-Σ_cN相互作用の重要性が指摘されている。ここでは、質量数３、４について、ストレンジネスとチャームの結合相互作用の違いと束縛エネルギーの違いを議論する。

山口康宏 (基研) 15:45-16:00
"パイオン交換相互作用による反DNN束縛状態"

アブストラクト：近年、ヘビーメソン(反D,Bメソン)と核子間に働くパイオン交換力による強い引力の存在が議論されている。このパイオン交換力は、ヘビークォークスピン対称性による擬スカラーメソンとベクターメソンの質量の縮退（例えばDメソンとD*メソンの質量縮退）により、ヘビーフレーバー領域で強調される。特に、反Dメソン（またはBメソン）と核子の間に引力が働くと、Strong decayに対して安定な「真にエキゾチックなフレーバー」を持った束縛状態の出現が期待できる。我々はヘビーメソンと核子による3体系に着目し、パイオン交換力が作る新たな束縛・共鳴状態について議論する。この解析では核力におけるパイオン交換でも重要な働きをしていた「テンソル力」と呼ばれる、異なる軌道角運動量状態を混ぜるような力が引力を生む主要な役割をしていることが得られた。

(*) 時間配分はおおよその目安です。

第４回格子QCD計算と現象論で探るハドロン間相互作用の理論の新展開

日時
2015年4月24日（金）11:00-16:00

場所
東京工業大学大岡山キャンパス本館155B号室場所

11:00-11:45 池田陽一 (理研)
"格子QCDのチャンネル結合散乱によるZc(3900)の構造"

11:45-12:30 佐々木健志 (筑波大)
"ΩN and ΩΩ interaction from Lattice QCD"

12:30-14:00 昼食

14:00-14:45 岡真 (東工大)
"ダイバリオン d*(2370)"

14:45-15:30 竹内幸子 (社会事業大)
"4 quark 系に働く力"

15:30-16:00 安井繁宏 (東工大)
"ヘビーハドロンのカイラル有効理論"

(*) 時間配分はおおよその目安です。

第３回ストレンジネス核物理の過去・現在・未来 --相互作用模型と格子QCDの視点から--

日時
2014年11月28日（金）14:00-17:30

場所
東京工業大学大岡山キャンパス本館第二会議室（345号室）場所

山本安夫 (都留文科大学) 14:00-16:00
"ストレンジネス核物理における相互作用模型の発展"

アブストラクト：1. overbinding problemとΛN-ΣN coupling
2. spin-spin interactionによる相互作用模型の選別
3. U_ΛとU_Σの統一的理解の重要性
4. 中性子星におけるhyperon mixingとユニバーサル多体斥力
5. エマルジョンイベントによるS=-2相互作用（ΛΛ,ΞN）の解明

井上貴史（日本大学）16:30-17:30
"格子QCDを用いたハイペロン力の研究 --現状と展望-- "

アブストラクト：我々 HALQCD Collaboration は、格子 QCD を用いてハドロン間相互作用の研究を行ってきた。今回の談話会では、ハイペロン力について、これまでに判った事とこれからの展望を話したい。
近年、ハイペロン力は中性子星との関連で特に注目されている。中性子星におけるハイペロンの出現がハイペロン力によって大きく左右されるからである。また、ハイペロン力はバリオン間力の一部と言う観点からも興味深い。なぜなら、ハイペロン力の情報は核力の解明につながると期待できるからである。核力がこの世界に極めて重要であるのは言うまでもない。これまで、ハイペロン力の研究は低エネルギー有効模型を用いて行われて来た。その際、情報量の少なさが障害となっており、実験データのさらなる充実が求められている。現在、JPARC を含む国内外の施設で実験が進行中または計画中であり、成果が期待される。一方、QCD に基づく研究は実験データや有効模型とは独立であり、相補的な関係にある。特にハイペロン間力は、実験が非常に困難であるため、QCD に基づく情報が重要になる。当日は、背景を含めた導入と HALQCD method の簡単な解説のあと、これまでに格子 QCD から導出されたハイペロン力を紹介し、時間が許せばその応用例も紹介したい。また、現在進行中の数値シミュレーションについても触れ、今後の展望を述べる。

(*) 時間配分はおおよその目安です。

第２回非平衡系からハドロン物理を考える<

日時
2014年8月1日（金）13:30から

場所
東京工業大学大岡山キャンパス本館第二会議室（345号室）場所

中村真 (中央大学)
"AdS/CFT対応を用いた非平衡統計物理学への挑戦"

アブストラクト：多体系の物理学は特定の分科を超えた物理学共通の研究課題の一つである。なかでも、平衡から離れた系の統計物理学を構成することは現代物理学の挑戦的な重要課題である。本講演では、この問題にAdS/CFT対応を応用し、従来とは異なる視点から非平衡物理学を記述する試みについて解説する。AdS/CFT対応とは、ある種の量子ゲージ理論とある種の古典重力理論の間の対応関係である。この対応を用いると、非閉じ込め相にあるゲージ粒子の多体系はブラックホール時空にマップされる。通常、温度やエントロピーといった巨視的物理量は微視的自由度の粗視化で得られるが、ブラックホール時空の場合、微視的理論と巨視的物理量をつなぐのは重力の古典方程式であり、具体的な統計分布の知識は顕わに必要とされない。この性質は、統計分布が明らかでない非平衡系の記述には強力な武器となり得る。本講演では、この重力の不思議な性質を利用し、非平衡系の統計的性質を探ってゆく。いったん平衡系が重力理論で準備されれば、外力でドライブすることで非平衡統計系を準備できるが、AdS/CFT対応では、外力の線形応答を超えた領域の計算が、比較的平易な古典方程式を解くことで遂行可能となる。当日の講演は２部に分け、前半はAdS/CFT対応一般の導入的解説を、後半は講演者らが最近精力的に行っている、非平衡定常系の物理学へのAdS/CFT対応の応用に関して解説する予定である。

第１回ハドロンの反応と構造から始めよう

日時
2014年5月9日（金）13:30から

場所
東京工業大学大岡山キャンパス本館第二会議室（345号室）場所

Yongseok Oh (Kyungpook National University)
"Recent topics in multi-strangeness hadrons: spectrum and production processes "

アブストラクト：The spectrum of baryon resonances can provide useful information on the structure of baryons. In particular, the spectra of multi-strangeness baryons are sensitive to the underlying dynamics of the system and show strong model-dependence. We will first discuss the issues in the spectra of Xi and Omega baryons and suggest a possible way to improve our understanding of strong interactions. Together with the spectrum study, investigation on the production process can probe the properties of baryon resonances. In the case of Xi production, the production mechanism should include many high-spin baryon resonances. We will discuss the role of high-spin resonances in Xi photoproduction by comparing our model calculations with experimental data. In addition, investigation on the anti-kaon-induced reactions to produce Xi baryons is crucial to determine the quantum numbers of Xi resonances. We will discuss the general formalism of this reaction as well. All these topics can be investigated experimentally at J-PARC and the upgraded JLab facilities.

吉田哲也 (東工大)
"P-wave heavy baryons in the constituent quark model"

アブストラクト：By the present, about 30 state of heavy baryons has been reported experimentally and we expect that more state will be discovered. The constituent quark model is the phenomenological model and fairly good for the baryon spectrum.we apply the constituent quark model to the heavy baryons to study the spectrum and its structure. In this talk, we show you the heavy baryon spectrum from the quark model calculation, and we introduce two excited mode called λ-mode and ρ mode.These two modes characterize P-wave state of singly and doubly heavy baryons.we find that singly heavy baryon is the state of λ-mode and doubly heavy baryon is the state of ρ-mode.

大古田俊介 (東工大)
"Heavy meson molecules in heavy quark limit"

アブストラクト：Heavy quark symmetry leads the spin degeneracy in heavy hadrons. We study the heavy meson molecules in the heavy quark limit and clarify the spin degeneracy of them. This study also provides information about the properties of the heavy meson molecules such as the probabilities of wave functions, decay and production ratios.

(*) 時間配分はおおよその目安です。