When the LHC starts its operation, CMS will have a unique opportunity to study q uarkonium production in pp collisions and later in PbPb collisions. Here we report on the methods and plans for measuring the differential pT Jpsi->mu+mu- production cross section, using data to be collected in the first LHC run by the CMS detector. Furthermore we discuss the performance of the CMS detector for quarkonium measurements in PbPb collisions.
The studies of heavy quarkonium inclusive production and polarization at LHC are becoming crucial to solve the puzzle of hadron formation. The results by CMS and the other LHC experiments are compactly presented for the five S-wave states J/Psi, Psi(2S) and Y(nS) (n=1,2,3) and briefly discussed especially in comparison to the theoretical predictions provided by Non Relativistic QCD.
The latest results of CMS in the area of exotic quarkonium decays will be presented: observation of a peaking structure in $J/ψΦ$ mass spectrum in the decay $B^\pm \rightarrow J/ψΦK^\pm$, search for new bottomonium states in $Υ(1\mathrm{S})π^+π^-$ mass spectrum, measurement of prompt $J/ψ$ pair production.
We propose an improved version of the color evaporation model to describe heavy quarkonium production. In contrast to the traditional color evaporation model, we impose the constraint that the invariant mass of the intermediate heavy quark-antiquark pair to be larger than the mass of produced quarkonium. We also introduce a momentum shift between heavy quark-antiquark pair and the quarkonium. Numerical calculations show that our model can describe the charmonium yields as well as ratio of $ψ^\prime$ over $J/ψ$ better than the traditional color evaporation model.
Heavy quarkonium production will provide for novel opportunities to study the gluonic structure of the nucleon in the near future. Near threshold quarkonium production allows for direct experimental access of the dynamic origin of the nucleon mass as well as the nature of the color Van der Waals force, while quarkonium production at high energies can be used to create a full three-dimensional tomographic image of the gluons inside the nucleon, constraining the gluonic radius of the nucleon.
The necessicity of the color-octet mechanism in describing heavy quarkonium production is a longstanding puzzle. Compared to the yields of heavy quarkonium, its polarizations should be a sensitive observable to pin down the color-octet contributions. In this talk, I will focus on the $χ_c$ polarization in hadroproduction processes, which may provide a unique test for the color-octet mechanism in nonrelativistic QCD.
Quarkonium production in heavy-ion collisions is a well-known signature of the formation of a plasma of quarks and gluons (QGP). After thirty years from the first measurements at SPS energies, a large wealth of results is now accessible from high-energy experiments at RHIC and LHC, and these new data are contributing to sharpen the picture of the quarkonium behaviour in A-A collisions. In this paper, an overview of the main results on both charmonium and bottomonium production in p-A and A-A collisions is presented, focussing on the most recent achievements from the RHIC and LHC experiments.
We review our recent understanding of quarkonium production at $e^+e^-$ and hadronic colliders from the point of view of potential non-relativistic QCD, and apply it to $P$-wave charmonium and bottomonium inclusive production.
The event generator BEEC [Z. Yang, X.G. Wu and X.Y. Wang, Comput. Phys. Commun. 184, 2848 (2013)] was devoted to the simulation of heavy quarkonium production at an unpolarized electron-positron collider. We upgraded it here by adding the generation of quarkonium with polarized electron and positron beams. In addition, the production of color-singlet 2S-wave states were included. Several future electron-positron colliders with high luminosity have been under discussion in the past decade. Especially, their possibility of producing polarized beams is important for providing more insights into t…
The double quarkonium production in single and double diffractive processes is investigated considering $pp$ collisions at the Run 2 LHC energy. Using the nonrelativistic QCD (NRQCD) factorization formalism for the quarkonium production and the Resolved Pomeron model to describe the diffractive processes, we estimate the rapidity and transverse momentum dependencies of the cross sections for the $J/ΨJ/Ψ$ and $ΥΥ$ production. The contributions of the color-singlet and color-octet channels are estimated and predictions for the total cross sections in the kinematical regions of the LHC experiment…
Being the "mother distributions" of all types of two-parton correlation functions, generalized transverse momentum dependent parton distributions (GTMDs) have attracted a lot of attention over the last years. We argue that exclusive double production of pseudoscalar quarkonia ($η_c$ or $η_b$) in nucleon-nucleon collisions gives access to GTMDs of gluons.
In this contribution we present opportunities to address questions about the origin of mass and spin, probe the existence and nature of the LHCb pentaquark state, and probe the color Van der Waal forces among two color neutral hadrons. The key reaction is elastic production of heavy quarkonia (J/psi and Upsilon) on the nucleon from threshold to large nucleon-quarkonium invariant masses. This is possible when combining the energy range of two high luminosity facilities, Jefferson Lab 12 GeV and an electron ion collider (EIC).
The widely used nonrelativistic QCD (NRQCD) factorization theory now encounters some notable difficulties in describing quarkonium production. This may be due to the inadequate treatment of soft hadrons emitted in the hadronization process, which causes bad convergence of velocity expansion in NRQCD. In this paper, starting from QCD we propose a rigorously defined factorization approach, soft gluon factorization (SGF), to better deal with the effects of soft hadrons. After a careful velocity expansion, the SGF can be as simple as the NRQCD factorization in phenomenological studies, but has a m…
Finite temperature QCD sum rules are applied to the behaviour of charmonium and bottonium states, leading to their survival at and beyond the critical temperature for deconfinement. Di-muon production in heavy-ion collisions in the $ρ$-region is also discussed.
We investigate light dark matter production associated with a heavy quarkonium at B factories in a model-independent way by adopting the effective field theory approach for the interaction of dark matter with standard model particles. We consider the effective operators for the dark matter-heavy quark interaction, which are relevant to the production of dark matter associated with a heavy quarkonium. We calculate the cross sections for dark matter production associated with a J/psi or eta_c to compare with the standard model backgrounds. We set bounds on the energy scale of new physics for var…
The production of a quarkonium -- pair in exclusive and diffractive processes in $pp$ collisions at the LHC and FCC energies is investigated. We consider the $J/ΨJ/Ψ$ and $ΥΥ$ production in these processes and present predictions for the transverse momentum and rapidity distributions considering the kinematical ranges expected to be covered by central and forward detectors. Results for the cross sections are also presented. Our results indicate that the double $J/Ψ$ production is dominated by the exclusive process, while the double $Υ$ production receive a large contribution of the diffractive…
In this paper, the soft gluon resummation effect in double heavy quarkonium production at the LHC is studied. By applying the transverse momentum dependent factorization formalism, the large logarithms introduced by the small total transverse momentum of heavy quarkonium pair final state system, are resummed to all orders in the expansion of the strong interaction coupling at the Next-to-Leading Logarithm accuracy. We also compare our result with the LHC data. We find that the distribution shape predicted by resummation calculation is consistent with experimental data very well. Since this pro…
The aim of this paper is to introduce a general way to stabilize the perturbative QCD computations of heavy quarkonium production in the boosted or high-momentum transferring region with tree-level generators only. Such an approach is possible by properly taking into account the power-enhanced perturbative contributions in a soft and collinear safe manner without requiring any complete higher-order computations. The complicated NLO results for inclusive quarkonium hadroproduction can be well reproduced within our approach based on a tree-level generator {\sc\small HELAC-Onia}. We have applied …
In this proceedings, we report the latest results of J/psi and Upsilon production from the STAR experiment at RHIC, in different colliding systems and colliding energies. J/psi nuclear modification factors (R_{AA}) in Au+Au collisions at 200, 62.4 and 39 GeV and in U+U collisions at 193 GeV, Upsilon R_{AA} in d+Au and Au+Au collisions at 200 and in U+U collisions at 193 GeV are shown and compared to different theoretical models. We also present prospects of quarkonium measurements at STAR.
The potential of the ALICE, ATLAS, CMS and LHCb detectors for the measurement of quarkonium in heavy-ion collisions, both in nucleus-nucleus (A-A) and in proton-nucleus (p-A) interactions, in the years 2015 until about 2030 in the LHC Runs 2, 3 and 4 with larger statistics and detector upgrades is described. A selection of newly available observables is discussed.
We show that when the factorized cross section for heavy quarkonium production includes next-to-leading power (NLP) contributions associated with the production of the heavy quark pair at short distances, it naturally reproduces all high $p_T$ results calculated in non-relativistic QCD (NRQCD) factorization. This extended formalism requires fragmentation functions for heavy quark pairs, as well as for light partons. When these fragmentation functions are themselves calculated using NRQCD, we find that two of the four leading NRQCD production channels, ${^3\hspace{-0.6mm}S_{1}^{[1]}}$ and ${^1\…
ALICE is designated to study the quark-gluon plasma (QGP), a state of matter where, due to high temperature and density, quarks and gluons are deconfined. One of the probes used to investigate this state of matter is quarkonium states, bound states of either a charm and anti-charm quark pair (charmonia) or a bottom and anti-bottom quark pair (bottomonia). The presence of the QGP is expected to modify the quarkonium production yields in a very specific way due to a balance between medium-induced suppression, and a recombination mechanism or a hadronization mechanism. To understand the the prope…
ALICE at the LHC has a unique potential to study proton-proton collisions with the goal to probe Quantum ChromoDynamics (QCD). The apparatus was designed to reconstruct particles over a large range in transverse momentum and rapidity. In particular, quarkonia are very interesting probes of QCD, because their production mechanisms are governed by both perturbative and non-perturbative QCD processes. In ALICE, quarkonia are reconstructed via their dilepton decay channel down to zero transverse momentum. This contribution gives a short overview of quarkonium production results in proton-proton co…
Due to the large masses of beauty and charm quarks, their production cross sections can be computed in the framework of perturbative Quantum Chromodynamics. The correlation of quarkonium and open heavy-flavour hadron yields with charged particles produced in proton-proton (pp) and proton-lead (p-Pb) collisions can shed light on the interplay between hard and soft mechanisms in particle production. In this proceeding the results from D-meson and J/$ψ$ yields as a function of the charged-particle multiplicity in pp and p-Pb collisions are presented. Comparisons to theoretical models are also dis…
I present a short review of recent studies of quarkonium production in proton-proton and proton-nucleus collisions at collider energies in Small-$x$ formalism.
At the LHC collision energies, multiple parton interactions (MPI) are a key ingredient for particle production models including hard scale processes like heavy-quark production (charm and beauty). Quarkonium measurements in high-multiplicity proton-proton (pp) collisions can shed light on the role of MPI at such hard momentum scales, as well as on the interplay between hard and soft particle production mechanisms. In addition, quarkonium production measurements in minimum bias pp collisions, besides serving as a reference for heavy-ion collisions collected at the same center-of-mass energy, re…
Quarkonium production as a function of the charged-particle multiplicity could provide an insight into particle production processes at the partonic level in hadronic collisions. It is believed that multiple partonic interactions play an important role in particle production and affect both soft and hard processes. The study of correlations between quarkonia and charged-particle multiplicity may provide information about this. In this contribution, ALICE measurements of J$/ψ$ and $Υ$ production as a function of charged-particle multiplicity are presented for pp collisions at center-of-mass ene…
I give a brief overview of the recent theoretical progress in the study of quarkonium production in proton-nucleus collisions in view of the recent LHC and RHIC results. A special emphasis is put on the excited states such as the psi', Upsilon(2S) and Upsilon(3S).
The precise mechanism for production of quarkonium at hadron colliders is still an open question. Within non-relativistic quantum chromodynamics, quarkonium production cross sections can be factorized into short-distance, perturbative contributions and universal, non-perturbative, long-distance matrix elements, and then summed over quantum numbers of the heavy quark pair. In principle, at short-distances, the heavy quark pair can be either in a color-singlet or color-octet state, and it is desirable to establish the relative contributions to compare with data and to make predictions in differe…
The production process of quarkonia in proton-proton (pp) collision is a very good probe of the parton structure of the proton. Recent experimental data of the production of J/psi+vector boson or quarkonium pairs at the LHC and Tevatron suggest the relevance of double parton scatterings (DPS). We discuss here the single parton scattering (SPS) contribution to the J/psi +Z, J/psi +W, and J/psi +J/psi productions in hadron collisions. By revisiting the computations of the SPS contributions to the J/psi+Z and J/psi +W productions, we demonstrate that the ATLAS data in fact show evidence for DPS.
Quarkonium production in proton-proton (pp) collision provides interesting means to study the parton content and their correlations in the proton. Recent LHC and Tevatron data of J/psi + Z, J/psi + W and J/psi +J/psi production suggest the relevance of double parton scatterings (DPSs) as opposed to single parton scatterings (SPSs). In this proceedings contribution, we review the corresponding SPS contributions and discuss their upper limits set up by quark-hadron duality. These allow us to perform an improved extraction of the DPS yields and of their implications.
Lindblad-driven quarkonium production in heavy-ion collisions
Instituto Galego de Física de Altas Enerxías IGFAE, Universidade de Santiago de Compostela（加利西亚高能物理研究所，圣地亚哥-德孔波斯特拉大学）；Departament de Física Quàntica i Astrofísica and Institut de Ciències del Cosmos, Universitat de Barcelona（量子物理与天体物理系及宇宙科学研究所，巴塞罗那大学）
