We present the first lattice result of the near threshold $ \Lambda_c\Lambda_c $ scattering with $ I(J^P) = 0(0^+) $ . The calculation is performed on two $ N_f = 2+1 $ Wilson-Clover ensembles with pion mass $ m_\pi \sim 303 $ MeV and lattice spacing $ a = 0.07746 $ fm. Lüscher's finite volume method is utilized to extract the scattering parameters from the finite-volume spectrum. The coupled channel $ \Xi_{cc}N $ is ignored in the scattering analysis based on the observation that the energy levels computed from the $ \Lambda_c\Lambda_c $ and $ \Xi_{cc}N $ operators do not mix. The $ \Sigma_c\Sigma_c $ channel is not included either since the energy range explored in this study is well below its threshold. Our results indicate that the interaction in the $ \Lambda_c\Lambda_c $ single channel is repulsive, and the scattering length is determined to be $ a_0 = -0.21(4)(8) $ fm, where the first error is statistical and the second is systematic.

China

Hanyang Xing

Yiqi Geng

Chuan Liu

Liuming Liu

Peng Sun

Jiajun Wu

Zhicheng Yan

Ruilin Zhu

Lattice QCD study of Λ $\textit{c}$ Λ $\textit{c}$ scattering * Supported by NSFC (12293060, 12293061, 12293063, 12175279, 12435002, 12322503, 12175239). L. Liu also acknowledges the Strategic Priority Research Program of the Chinese Academy of Sciences with (XDB34030301) and Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008). We also acknowledge the Science and Education Integration Young Faculty Project of University of Chinese Academy of Sciences (YSBR-101)

We study the <math altimg='si1.svg'><msubsup><mrow><mi>B</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msubsup></math> production in Pb-Pb collisions at <math altimg='si2.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>5.02</mn></math> TeV. In the quark-gluon plasma (QGP) produced in heavy-ion collisions, heavy quarks make random motions with the energy loss. We employ the Langevin equations to study the non-equilibrium distributions of heavy quarks and the Instantaneous Coalescence Model (ICM) to study the hadronization process. Due to abundant charm and bottom quarks in the QGP, their coalescence probability is significantly enhanced compared with the situations in proton-proton collisions. We find that the final production of <math altimg='si1.svg'><msubsup><mrow><mi>B</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msubsup></math> is increased by the coalescence process, which makes the nuclear modification factor ( <math altimg='si3.svg'><msub><mrow><mi>R</mi></mrow><mrow><mi>A</mi><mi>A</mi></mrow></msub></math>) of <math altimg='si1.svg'><msubsup><mrow><mi>B</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msubsup></math> larger than unit. Our model explains the experimental data well at semi-central and central collisions. The observation of <math altimg='si4.svg'><msub><mrow><mi>R</mi></mrow><mrow><mi>A</mi><mi>A</mi></mrow></msub><mo stretchy='false'>(</mo><msubsup><mrow><mi>B</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msubsup><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>&gt;</mo><mn>1</mn></math> is regarded as an evident and strong signal of the existence of the deconfined medium generated in heavy-ion collisions.

Baoyi Chen

Liuyuan Wen

Yunpeng Liu

<math altimg='si1.svg'><msubsup><mrow><mi>B</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msubsup></math> formation from random charm and anti-bottom quarks in the quark-gluon plasma

Heavy-ion collisions provide a unique opportunity to study the nature of X(3872) compared with electron-positron and proton-proton (antiproton) collisions. We investigate the centrality and momentum dependence of <math><mrow><mi>X</mi><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></math> in heavy-ion collisions via the Langevin equation and instant coalescence model (LICM). When <math><mrow><mi>X</mi><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></math> is treated as a compact tetraquark state, the tetraquarks are produced via the coalescence of heavy and light quarks near the quantum chromodynamic phase transition due to the restoration of the heavy quark potential at <math><mrow><mi>T</mi><mo>→</mo><msub><mi>T</mi><mi>c</mi></msub></mrow></math>. In the molecular scenario, loosely bound <math><mrow><mi>X</mi><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></math> is produced via the coalescence of <math><mrow><msup><mi>D</mi><mn>0</mn></msup><mtext>−</mtext><msup><mover><mi>D</mi><mo>¯</mo></mover><mrow><mo>*</mo><mn>0</mn></mrow></msup></mrow></math> mesons in a hadronic medium after kinetic freeze-out. We employ the LICM to explain both <math><msup><mi>D</mi><mn>0</mn></msup></math> and <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> production as a benchmark. Then we give predictions regarding <math><mrow><mi>X</mi><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></math> production and the nuclear modification factor <math><msubsup><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow><mrow><mi>X</mi><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></msubsup></math>. 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 <math><msup><mi>D</mi><mn>0</mn></msup></math> and <math><msup><mover><mi>D</mi><mo>¯</mo></mover><mrow><mo>*</mo><mn>0</mn></mrow></msup></math> in the molecular Wigner function, which significantly suppresses the molecular yield.

Liu Jiang

Xiao-Hai Liu

Jiaxing Zhao

<math><mrow><mi>X</mi><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></math> production in relativistic heavy-ion collisions

This exploratory study computes two-photon decay widths of pseudo-scalar (
					) and scalar (
					) charmonium using two ensembles of 
					 twisted mass lattice QCD gauge configurations. The simulation is performed using two lattice ensembles with lattice spacings 
					 fm with size 
					 and 
					 fm with size 
					. The decay widths for the two charmonia are obtained within the expected ballpark, but are however smaller than the experimental ones. Possible reasons for these discrepancies are discussed.
				

Ying Chen

Ming Gong

Ning Li

Yu-Bin Liu

Zhaofeng Liu

Jian-Ping Ma

Yu Meng

Chao Xiong

Ke-Long Zhang

Lattice study of two-photon decay widths for scalar and pseudo-scalar charmonium This work is supported in part by the National Science Foundation of China (NSFC) (11335001, 11275169, 11405178, 11935017, 11575196, 11875169, 11775229). It is also supported in part by the DFG and the NSFC (11261130311) through funds provided to the Sino-Germen CRC 110 symmetries and the Emergence of Structure in QCD. This work is also funded in part by National Basic Research Program of China (973 Program) (2015CB856700). M. Gong and Z. Liu are partially supported by the Youth Innovation Promotion Association of CAS (2013013). This work is also supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department (19JK0391) andNatural Science Basic Research Plan in Shaanxi Province of China (2019JM-001)

Using the one-boson-exchange model, we investigate the , , , , , and interactions by considering the one-eta-exchange and/or one-pion-exchange contributions. We further predict the existence of hidden-charm molecular pentaquarks. Promising candidates for hidden-charm molecular pentaquarks include a state with and the states with and . Experimental searches for these predicted hidden-charm molecular pentaquarks are an interesting future research topic for experiments like LHCb.

Rui Chen

Jun He

Xiang Liu

Possible strange hidden-charm pentaquarks from and interactionsSupported by National Natural Science Foundation of China (11222547, 11175073, 11675228), Major State Basic Research Development Program in China (2014CB845405) and Fundamental Research Funds for the Central Universities. Xiang Liu is also supported by the National Program for Support of Top-notch Young Professionals

We study cold and hot nuclear matter effects on charmonium production in p+Pb collisions at sNN=5.02Â TeV in a transport approach. At the forward rapidity, the cold medium effect on all the ccÂ¯ states and the hot medium effect on the excited ccÂ¯ states only can explain well the J/Ï and Ïâ² yield and transverse momentum distribution measured by the ALICE collaboration, and we predict a significantly larger Ïâ² pT broadening in comparison with J/Ï . However, we can not reproduce the J/Ï and Ïâ² data at the backward rapidity with reasonable cold and hot medium effects.

Tiecheng Guo

Pengfei Zhuang

Cold and hot nuclear matter effects on charmonium production in p+Pb collisions at LHC energy

We investigate the production of Î©ccc baryon in high energy nuclear collisions via quark coalescence mechanism. The wave function of Î©ccc is solved from the SchrÃ¶dinger equation for the bound state of three charm quarks by using the hyperspherical method. The production cross section of Î©ccc per binary collision in a central Pb+Pb collision at sNN=2.76Â TeV reaches 9 nb, which is at least two orders of magnitude larger than that in a p+p collision at the same energy. Therefore, it is most probable to discover Î©ccc in heavy ion collisions at LHC, and the observation will be a clear signature of the quarkâgluon plasma formation.

Hang He

Ωccc Production in High Energy Nuclear Collisions

Based on a kinetic description of J/ψ dissociation and production in an expanding quark–gluon plasma that is described by a 2+1 dimensional ideal hydrodynamics, we have studied the hot medium effects on J/ψ production in p+Pb collisions at sNN=5.02 TeV . Including also the cold nuclear matter effects, we are able to reproduce recent experimental results on the nuclear modification factor RpPb(J/ψ) measured by the ALICE Collaboration. We have also made predictions for the RpPb of J/ψ and the double ratio RpPbpro(ψ′)/RpPbpro(J/ψ) of prompt quarkonia produced in the most central 10% p+Pb collisions. We find that different from the cold nuclear matter effects, the RpPb(J/ψ) is slightly smaller than that in the minimum bias collisions, and the double ratio is significantly less than one at backward rapidity.

United States

Che Ming Ko

Taesoo Song

Hot medium effects on J/ψ production in p+Pb collisions at sNN=5.02 TeV