Exotics and Exotic Phenomena in Heavy Ion Collisions (ExHIC)

APCTP Headquarters

APCTP Headquarters

Pohang, Korea
Su Houng Lee (Chair) (Yonsei University), Sungtae Cho (Kangwon National University), Xu-Guang Huang (Fudan University), Yongseok Oh (Kyungpook National University), Akira Ohnishi (Yukawa Institute for Theoretical Physics, Kyoto University), Eunsook Lee (Staff) ((Staff))

In February 2021, the CMS collaboration has reported the observation of X(3872) with anomalously large production yield in Pb-Pb heavy ion collision at 5.02 TeV. Such a large production rate was anticipated by the ExHIC (Exotics from Heavy Ion Collision)  theory collaboration, formed by the present organizers, in a PRL paper, which showed that the large hadron production yields in heavy ion collision could be used to discriminate a molecular from a compact configuration for an exotic hadron.  The work was an outcome of the discussion in the ExHIC inauguration workshop held in 2011 at Yukawa Institute, Kyoto. Furthermore, in July 2021, the LHCb collaboration has observed a doubly charmed meson Tcc, which has been extensively discussed in the 2007 APCTP program on “Hadron Physics at RHIC” organized by the present PI and collaborators with subsequent pioneering publications on the exotic hadron.  

Therefore, in the proposed focus program, the original authors of the pioneering works aim at bringing together experimentalists and theorists on the subject to discuss the current status of the newly developing subject and to probe future research direction.  We will also asses the possibilities of measuring Tcc for the first time from a heavy ion collision and what other measurements for the X(3872) and other hadron physics related observables would be feasible and useful. This will be a continuation of the 2007 APCTP focus program on “Hadron Physics at RHIC” and the extension of the ExHIC collaboration formed in the “Exotics in heavy ion collision (ExHIC)” workshops at YITP in 2011 and “Exotic Phenomena in heavy ion collision (ExHIC-p)” in 2019.

This meeting will be held in the hybrid mode.

Zoom link:    https://us06web.zoom.us/meeting/register/tZYpcuiurDstE9MXF4iFpFnVF1mq61b0CBGi

ID :  824 5162 0797

PW : 0000

  • Ahmad Jafar Arifi
  • Akira Ohnishi
  • Avraham Gal
  • Baoyi Chen
  • Benjamin Doenigus
  • Bo Wang
  • Chang Ho Hyun
  • Che-Ming Ko
  • Guang-Juan Wang
  • Haesom Sung
  • Hongxi Xing
  • Hyung-Ok Yoon
  • Ibuki Terashima
  • Junlee Kim
  • Kiyoshi Tanida
  • Lata Thakur
  • Lu Meng
  • MinJung Kweon
  • Parada Tobel Paraduan Hutauruk
  • Pengfei Zhuang
  • Philipp Gubler
  • Priyanshu Gupta
  • Qian Wang
  • Sanghoon Lim
  • Seokwoo Yeo
  • Seung-il Nam
  • Shigehiro Yasui
  • Shung-Ichi Ando
  • Su Houng Lee
  • Sungtae Cho
  • Sunil Manohar Dogra
  • Takayasu Sekihara
  • Takuya Sugiura
  • Tetsuo Hatsuda
  • Tetsuo Hyodo
  • Tomona Kinugawa
  • Ulrich Wiedner
  • William Jin
  • Xu-Guang Huang
  • Yasuhiro Yamaguchi
  • Yongseok Oh
  • Yongsun Kim
  • Yorito Yamaguchi
  • Zhenwei Yang
    • 9:00 AM 10:30 AM
      Session: 1
      Convener: Che-Ming Ko (Texas A&M University)
      • 9:00 AM
        Opening 10m
        Speaker: Su Houng Lee (Yonsei University)
      • 9:10 AM
        Overview of previous programs and ExHIC meetings 40m
        Speaker: Su Houng Lee (Yonsei University)
      • 9:50 AM
        Femtoscopic study of flavored hadron interactions and ExHIC 40m
        Speaker: Akira Ohnishi (Yukawa Institute for Theoretical Physics, Kyoto University)
    • 10:30 AM 11:00 AM
      Break 30m
    • 11:00 AM 12:00 PM
      Session: 2
      Convener: Che-Ming Ko (Texas A&M University)
      • 11:00 AM
        Hadron interactions from Lattice QCD 30m
        Speaker: Tetsuo Hatsuda (RIKEN)
      • 11:30 AM
        Fully-heavy flavor hadrons in nuclear collisions 30m
        Speaker: Pengfei Zhuang (Tsinghua Univ.)
    • 12:00 PM 2:00 PM
      Lunch 2h
    • 2:00 PM 3:30 PM
      Session: 3
      Convener: Akira Ohnishi (Yukawa Institute for Theoretical Physics, Kyoto University)
      • 2:00 PM
        Exotic hadrons at LHCb 30m
        Speaker: Zhenwei Yang (Peking Univ,)
      • 2:30 PM
        Exotic hadrons in the hybrid model of hadronic molecules and compact states 30m

        Hadrons have been understood as a quark-gluon composite state bound by the strong interactions, which is one of the interesting phenomena in the low-energy QCD. As the ordinary hadron picture, baryons and mesons are described as a three-quark state and quark-antiquark state, respectively. In fact, nucleons (protons and neutrons) can be understood as $uud$ and $udd$ baryons. However, accelerator experiments have reported unexpected states called exotic hadrons. The exotics cannot be understood by the ordinary hadron picture. The experimental observations indicate that the exotic hadrons have multiquark structures such as a compact multiquark, e.g. $qq\bar{q}\bar{q}$ and $qqqq\bar{q}$, and a hadron composite state called hadronic molecule. Theorists have studied natures of the exotics by using various approaches e.g. an effective model, QCD sum rules, and lattice QCD. However, the exotic hadron problem is still an open question.
        In this work, we study the exotic hadrons by employing the hybrid model considering the mixture of the hadronic molecule and compact state. The hadronic molecular component is expected to be important in exotic hadrons near thresholds. We also discuss the role of the coupling to the compact state, which plays an important role to provide the strong attraction in the hadronic molecule. By employing the hybrid model, we study the $P_c$ and $P_{cs}$ pentaquarks reported by the LHCb collaboration recently. We compute energies of these exotics and also discuss roles of the interactions.

        Speaker: Yasuhiro Yamaguchi
      • 3:00 PM
        Recent results from $e^+ e^-$ collisions at Belle and Belle II 30m
        Speaker: Kiyoshi Tanida (Japan Atomic Energy Agency)
    • 3:30 PM 4:00 PM
      Break 30m
    • 4:00 PM 5:30 PM
      Session: 4
      Convener: Akira Ohnishi (Yukawa Institute for Theoretical Physics, Kyoto University)
      • 4:00 PM
        Recent news from hypernuclei 30m
        Speaker: Avraham Gal (Hebrew University)
      • 4:30 PM
        Future ALICE measurement 30m
        Speaker: Minjung Kwon (Inha University)
      • 5:00 PM
        Long-range structure of $T_{cc}^+$ state 30m
        Speaker: Lu Meng (Ruhr Univ.)
    • 9:00 AM 10:30 AM
      Session: 5
      Convener: Yongseok Oh
      • 9:00 AM
        Kinetic approach to light nuclei production 30m
        Speaker: Che-Ming Ko (Texas A&M University)
      • 9:30 AM
        Resonance Production in Heavy Ion Collision 30m
        Speaker: Jihye Song (Pusan National University)
      • 10:00 AM
        Production of Molecular configurations in heavy ion collisions 30m
        Speaker: Hyung-Ok Yoon (Yonsei Univ.)
    • 10:30 AM 11:00 AM
      Break 30m
    • 11:00 AM 12:00 PM
      Session: 6
      Convener: Yongseok Oh (Kyungpook National University)
      • 11:00 AM
        Understanding the nature of light scalar meson with ALICE 30m
        Speaker: Junlee Kim (Jeonbuk National University)
      • 11:30 AM
        $\phi$ meson polarizations 30m
        Speaker: Philipp Gubler (JAEA)
    • 12:00 PM 2:00 PM
      Lunch 2h
    • 2:00 PM 3:30 PM
      Session: 7
      Convener: Su Houng Lee (Yonsei University)
      • 2:00 PM
        Bound and resonant tetraquarks 30m
        Speaker: Atsushi Hosaka (RCNP, Osaka University)
      • 2:30 PM
        Exploring the nature of $X(3872)$ in heavy ion collisions 30m
        Speaker: Hongxi Xing (South China Normal University)
      • 3:00 PM
        Production of the $T_{cc}$ and the $X(6900)$ in heavy ion collision 30m

        The nature of exotic hadrons beyond the conventional quark model has being a hot topic in hadron physics. Since the observation of the first exotic charmonium-like state, i.e. the X(3872), numerous exotic candidates have been reported by various experimental collaboration. Especially, the fully charm tetra quark X(6900) and the double charm tetraquark Tcc observed in pp collision arouse intensive discussion among the community. In this talk, I will discuss the production of the Tcc and the X(6900) in heavy ion collision, which includes the pT, rapidity, centrality, polar angle distributions and so on.

        Speaker: Qian Wang (South China Normal University)
    • 3:30 PM 4:00 PM
      Break 30m
    • 4:00 PM 6:00 PM
      Session: 8
      Convener: Su Houng Lee (Yonsei University)
      • 4:00 PM
        The search for exotic particles 30m
        Speaker: Ulrich Wiedner (Ruhr-University Bochum)
      • 4:30 PM
        Production of loosely bound objects in heavy-ion collisions 30m
        Speaker: Benjamin Doenigus (Goethe-University Frankfurt)
      • 5:00 PM
        A theoretical support for the discovery of the $\bar{K}NN$ nucleus at J-PARC and its perspective/implication in heavy ion collision 30m
        Speaker: Takayasu Sekihara (Kyoto Prefectural University)
      • 5:30 PM
        Charmed hadrons on lattice QCD 30m
        Speaker: Takuya Sugiura (RIKEN)
    • 9:00 AM 10:30 AM
      Session: 9
      Convener: Xu-Guang Huang (Fudan University)
      • 9:00 AM
        Anti-$D$ meson and nucleon interaction from meson exchange model 30m

        We discuss the interaction between an anti-$D$ meson and a nucleon in terms of the meson exchange model. We provide the interaction vertices and the non-relativistic potentials, based on the chiral symmetry and the heavy quark spin symmetry. In numerical calculations, we show several bound states below the lowest thresholds, which contain at least five quarks as the pentaquark states. We compare our results with the experimental data reported by ALICE in LHC. We apply a similar discussion to the bottom sector.

        Speaker: Shigehiro Yasui (Keio University)
      • 9:30 AM
        $X(3872)$, $B_c$ and charmonium production via coalescence in heavy-ion collisions 30m

        We investigate the centrality and momentum dependence of X(3872) in heavy-ion collisions via the Langevin equation and instant coalescence model (LICM). When X(3872) is treated as a compact tetraquark state, the tetraquarks are produced via the coalescence of heavy and light quarks near the quantum chromodynamic (QCD) phase transition due to the restoration of the heavy quark potential at $T\rightarrow T_c$. In the molecular scenario, loosely bound X(3872) is produced via the coalescence of $D^0$-$\bar D^{*0}$ mesons in a hadronic medium after kinetic freeze-out. We employ the LICM to explain both $D^0$ and $J/\psi$ production as a benchmark. Then we give predictions regarding X(3872) production and the nuclear modification factor $R_{AA}^{X(3872)}$. We find that the total yield of tetraquark is several times larger than the molecular production in Pb-Pb collisions. Although the geometric size of the hadronic molecule is huge, the coalescence probability is small due to strict constraints on the relative momentum between $D^0$ and $\bar D^{*0}$ in the molecular Wigner function, which suppresses the molecular yield. Based on the same approach, we calculated the $R_{AA}(B_c)$ which can explain well the experimental data published recently.

        Speaker: Baoyi Chen (Tianjin University)
      • 10:00 AM
        Recent activities on multi-strange dibaryon searches at LHC energy 30m
        Speaker: Yorito Yamaguchi (Hiroshima University)
    • 10:30 AM 11:00 AM
      Break 30m
    • 11:00 AM 12:30 PM
      Session: 10
      Convener: Sungtae Cho (Kangwon National University)
    • 12:30 PM 2:00 PM
      Lunch 1h 30m
    • 2:00 PM 3:40 PM
      Session: 11
      Convener: Yongsun Kim (Sejong University)
      • 2:00 PM
        Monte Carlo simulation for quarkonia production in heavy-ion collisions 30m
        Speaker: Sanghoon Lim (Pusan National University)
      • 2:30 PM
        Feasibility study of $X(3872)$ and $T_{cc}$ at LHC Run 3 30m
        Speaker: Bunkyu Kim (SungKyunKwan Univ.)
      • 3:00 PM
        Heavy quark coalescence 40m
        Speaker: Sungtae Cho (Kangwon National University)
    • 3:40 PM 4:00 PM
      Break 20m
    • 4:00 PM 5:30 PM
      Session: 12
      Convener: Sanghoon Lim (Pusan National University)
      • 4:00 PM
        Spin polarization in heavy ion collisions 30m
        Speaker: Xu-Guang Huang (Fudan University)
      • 4:30 PM
        $D_s(2590)^+$: a conventional or exotic state? 30m
        Speaker: Ahmad Jafar Arifi (APCTP)
    • 6:30 PM 10:00 PM
      Organization committee meeting: