# FCPPL Quarkonium Production Workshop

Asia/Shanghai
Peking University

#### Peking University

B105, West Building of School of Physics (Next to the Metro Station "PKU East Gate", across the street from the main PKU entrance)
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Participants
• Antonio Uras
• Baoyi Chen
• Brigitte Cheynis
• Gines Martinez-Garcia
• Hong-Fei Zhang
• Jean-Marc Richard
• Jean-Philippe Lansberg
• Jiajia Qin
• Jianxiong Wang
• Jiaxing Zhao
• Jibo He
• Kuang-Ta Chao
• Liupan An
• Min Jung Kweon
• Patrick Robbe
• Peng Zhang
• Pengfei Wang
• Pengfei Zhuang
• Rong Li
• Sergey Barsuk
• Wangmei Zha
• Yan-Qing Ma
• Yiming Li
• Yu Feng
• Yu-Jie Zhang
• Zebo Tang
• Zhenwei Yang
• Thursday, March 30
• Proton-proton collisions
• 1
Welcome
• 2
Experimental study of quarkonium production in pp collisions

The experimental study of quarkonium production in pp collisions will be reviewed in this talk.

Speaker: Jibo He (University of Chinese Academy of Sciences (CN))
• 3
Introductory theoretical talk
Speaker: Jianxiong Wang (IN)
• 4
Energy dependence of direct-quarkonium production in pp collisions from fixed-target to LHC energies:complete one-loop analysis.

We compute the energy dependence of the pt-integrated cross section of directly produced quarkonia in pp collisions at next-to-leading order within the nonrelativistic QCD framework. We treat the pt-integrated and the pt-differential cross sections as two different observables to investigate whether the CO LDMEs extracted from the fits of the pt-differential cross sections can predict the pt-integrated cross sections. We also consider the cross sections calculated in CSM and CEM. Our study do not support the past claims that color-octet transitions are dominantly responsible for low-pt quarkonium prodution.

Speaker: Yu Feng (Third Military Medical University, Chongqing,Southwest of China)
• 4:20 PM
Coffe break
• 5
Analytical Calculation for the Gluon Fragmentation into Spin-triplet S-wave Quarkonium

Fragmentation function of gluon to the spin-triplet color-singlet S-wave quarkonium has been calculated numerically earlier in 1992. However, the analytical result is absent because of the complex high dimensional integrals. With the development of the high-loop calculation, we consider to solve the problem with the IBP reduction. I will present our method and the final result, which is compatible with the numerical value before. Furthermore, we give the polarization results and the corresponding relative-$v^2$ corrections.

Speaker: Peng Zhang (Peking University)
• 6
A new factorization theory for quarkonium production and decay
Speaker: Yan-Qing Ma (BNL)
• 7
Round table on current th & exp results
• Friday, March 31
• Proton-nucleus collisions
• 8
Quarkonium production in p(d)+A collisions at LHC and RHIC

An overview on recent experimental measurements about quarkonia productions in proton(deuteron)-ion collisions at LHC and RHIC will be presented.

Speaker: Xianglei ZHU (Tsinghua University)
• 9
Theory of quarkonium production in proton-nucleus collisions
Speaker: Hong-Fei Zhang
• 10
Round table
• 10:15 AM
Coffee break
• 11
On the Psi(2S) over J/psi production yield in pp and pA collisions

Proton nucleus collisions are expected to be unique tool to probe the physics of the initial state of ultra relativistic heavy ion collisions, without the presence of thermalisation and collective evolution of high energy density QCD matter. However, many observations related to the production of light and strange hadrons at low transverse momentum (pT) in p-Pb collisions at the LHC surprisingly exhibit a qualitative similarity to measurements in nucleus-nucleus collisions and are in qualitative agreement with hydrodynamical model
8 calculations. Similar observations have been performed in high multiplicity proton-proton collisions at the LHC. On the other hand, the experimental results of high pT hadrons, jet, heavy quarks production in p-Pb collisions at the LHC can be explained as binary scaling with respect to pp collisions with a moderate shadowing effect as expected in the absence of collective phenomena. In the case of J/ψ and Υ(1S) production an additional energy loss mechanism has to be considered to explain their production. Among the hard probes, only the Ψ(2S), Υ(2S) and Υ(3S) exhibit a puzzling behaviour in proton-nucleus collisions at the LHC, also observed for the Ψ(2S) in central d-Au collisions at RHIC, and which violate the binary scaling. A priori, the observed relative suppression of theses quarkonium resonances in p-A collisions, ravels the interpretation of the experimental results obtained in A-A collisions.

Speaker: Dr Gines Martinez-Garcia (Subatech CNRS)
• 12
Cold and hot medium effects on charmonium production in 5.02 TeV p-Pb collisions

We study cold and hot nuclear matter effects on charmonium production in p+Pb collisions at$\sqrt{s_{NN}}$ = 5.02 TeV in a transport approach. As cold nuclear matter effects give almost the same modification on different $c\bar c$ states at the LHC energy, different nuclear modification factors of $J/\psi$ and $\psi^\prime$ indicate the existence of the hot medium. In forward rapidity, we can explain well the $J/\psi$ and $\psi^\prime$ yield and transverse momentum distribution measured by the ALICE collaboration, and we predict a significantly larger $\psi^\prime$ broadening in comparison with $J/\psi$. However, we can not reproduce the $J/\psi$ and $\psi^\prime$ data at the backward rapidity with reasonable cold and hot medium effects.

Reference: Phys.Lett. B765 (2017) 323-327

Speaker: Dr Baoyi Chen (Tianjin University)
• 13
Round table
• 12:40 PM
Lunch
• Nucleus-nucleus collisions
• 14
Theory of quarkonium production and suppression in nuclear collisions

I will discuss in this talk the mechanisms for quarkonium production and suppression in high energy nuclear collisions from SPS to RHIC, LHC and FCC energies.

Speaker: Prof. pengfei zhuang (tsinghua university)
• 15
Quarkonium production in heavy-ion collisions at SPS and RHIC
Speaker: Zebo Tang (University of Science and Technology of China)
• 16
Quarkonium produciton in nucleus-nucleus collisions at LHC
Speaker: Min Jung Kweon (Inha University (KR))
• 3:55 PM
Coffee break
• 17
Calculation of coherent J/$\psi$ photoproduction in hadronic A+A collisions at RHIC and LHC

The coherent photon-nucleus interactions has been studied in detail at RHIC and LHC to probe the gluon distribution in nucleus at low Feynman $x$ via relativistic heavy-ion collisions. These kind of interactions are traditionally thought to only exist in ultra-peripheral collisions, where there is no hadronic interactions. Recently, a significant excess of J/$\psi$ yield at very low transverse momentum ($p_T < 0.3$ GeV/c) was observed by the ALICE and STAR collaborations in peripheral A+A collisions, which points to evidence of coherent photoproduction of J/$\psi$ in violent hadronic interactions. The survival of photoproduced J/$\psi$ merits theoretical investigation. In addition, with respect to the expectation of theoretical calculations, the excess yield of $J/\psi$ in hadroinc heavy-ion collisions may served as a good probe to test the cold and hot medium effects.

In this presentation we report on calculations of coherent photon-nucleus ($\gamma + A \rightarrow J/\psi + A$) interactions in hadronic A+A collisions at RHIC and LHC energies. We also address the questions about how the electromagnetic field translates into a flux of equivalent photons in hadronic A+A collisions: if the photons is emitted from the whole nucleus, or if only the spectator fragments contribute to the photon emission. Similarly, it is not clear whether the whole nucleus or only spectator fragment act as photon target. The model used to calculate the cross section will be discussed and the expected yield will be compared with experimental results from RHIC and LHC. The differential centrality, rapidity and transverse momentum distributions from calculations will also be compared between different scenarios.

Speaker: Wangmei Zha (USTC/BNL)
• 18
Double charm baryon production

We ﬁrst study the doubly charmed baryon $\Xi_{cc}^+$ structure and yield in high energy nuclear collisions. Using hypericspherical expansion method, we solved the three-body Schr¨odinger equation including relativistic correction and calculate the yield of $\Xi_{cc}^+$ via coalescence mechanism. We ﬁnd that, the $\Xi_{cc}^+$ created in heavy ion collision is like a quark-diquark state as a consequence of chiral symmetry restoration in hot medium, and the yield is extremely enhanced due to the large number of charm quarks.

Speaker: jiaxing zhao
• 19
Round table
• Saturday, April 1
• Prospects for the fixed target mode at the LHC
• 20
Results from SMOG-LHCb
Speaker: Patrick Robbe (Universite de Paris-Sud 11 (FR))
• 21
The AFTER@LHC project and quarkonium production studies
Speaker: Jean-Philippe Lansberg (IPN Orsay, Paris Sud U. / IN2P3-CNRS)
• 10:30 AM
Coffee break
• 22
Round table
• 12:00 PM
Lunch
• New observables

Quarkonium pair, quarkonium + vector boson, quarkonium + heavy quarks, Higgs to J/psi+gamma, ...

• 23
Double heavy production in high energy colliders

Two or more heavy quark-antiquark pairs can be produced in high energy collisions, not only because of increase of centre-of-mass energy, but also due to multiple parton scattering in case of hadron collisions. This will be a brief experimental overview on the double heavy production involving at least one quarkonium in the final state in $pp$ collisions at LHC, as well as in $e^{+} e^-$ collisions at B-factories.

Speaker: Dr Yiming Li (IHEP, CAS)
• 24
$\Upsilon+J/\psi$ and $J/\psi+J/\psi$ production at hadron colliders and double patron scattering

We present the first complete study of $\Upsilon$ and prompt $J/\psi$ production from single-parton scattering to the complete O($\alpha_s^6$) for color singlet contribution and including all leading SPS contributions. We find that the effective cross section characterizing the importance of double-parton scatterings is $\sigma_{eff}$≤8.2  mb at 68% confidence level from the D0 measurement. At the same time, we also present $J/\psi+J/\psi$ production at hadron colliders.

Speaker: Dr Yu-Jie Zhang (Beihang University)
• 25
Round table on double HQ production
• 4:05 PM
Coffee break
• 26
Stability of fully heavy tetraquarks

We discuss the stability of tetraquarks systems made of two heavy quarks and two heavy antiquarks, with a potential model whose linear part is inspired by string dynamics.

At variance with some recent or less recent claims, we do not find binding for the double-charmonium or double-bottomonium cases. The string dynamics is, however, more favorable for (bcb̄c̄), i.e., a charmonium-bottomonium compound.

Some comments are made on the diquark-antidiquark approximation for describing these structures.

This talk is based on the paper: arXiv:1703.00783, to appear in Phys. Rev D.

Speaker: Jean-Marc Richard (IPNL)
• 27
Associate Production of Quarkonium with a Vector Boson

Here is a brief overview on the quarkonium production associated with a vector boson, such as photon, W or Z.

Speaker: Dr Rong Li (Xi'an Jiaotong University)
• 28
Round table on NRQCD fits and new observables