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Z -boson decays to a vector quarkonium plus a photon
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Recent Quarkonium Studies from the PHENIX Experiment
Quarkonia suppression in nucleus-nucleus collisions is a powerful tool to probe the density and temperature of the medium created in heavy ion collisions. Forward rapidity measurements in p(d)+Au collisions are essential to understand how quarkonia states are affected by initial state effects, formation time, and local particle multiplicity. Earlier measurements in Au+Au collisions showed a stronger suppression of forward J/Ψ compared to mid-rapidity results, indicating the possibility of a smaller contribution of regenerated quarkonia states at forward rapidity. These proceedings report on the latest quarkonia studies performed by the PHENIX collaboration in the rapidity range 1:2 < |y| < 2:2.
General form of s , t , and u symmetric polynomials and heavy quarkonium physics
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Search for B \to K(*)nunubar and Invisible Quarkonium Decays
Abstract Not Provided
Heavy quarkonium production at collider energies: Factorization and evolution
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Puzzles in hadronic transitions of heavy quarkonium with two pion emission
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New approach to the resummation of logarithms in Higgs-boson decays to a vector quarkonium plus a photon
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Heavy Quarkonium and Quarkonium-Like States at Belle and BaBar
Abstract Not Provided
Quarkonium semiclassical transport in quark-gluon plasma: factorization and quantum correction
We study quarkonium transport in the quark-gluon plasma by using the potential nonrelativistic QCD (pNRQCD) effective field theory and the framework of open quantum systems. We argue that the coupling between quarkonium and the thermal bath is weak using separation of scales, so the initial density matrix of the total system factorizes and the time evolution of the subsystem is Markovian. We derive the semiclassical Boltzmann equation for quarkonium by applying a Wigner transform to the Lindblad equation and carrying out a semiclassical expansion. We resum relevant interactions to all orders in the coupling constant at leading power of the nonrelativistic and multipole expansions. The derivation is valid for both weakly coupled and strongly coupled quark-gluon plasmas. We find reaction rates in the transport equation factorize into a quarkonium dipole transition function and a chromoelectric gluon distribution function. For the differential reaction rate, the definition of the momentum dependent chromoelectric gluon distribution function involves staple-shaped Wilson lines. For the inclusive reaction rate, the Wilson lines collapse into a straight line along the real time axis and the distribution becomes momentum independent. The relation between the two Wilson lines is analogous to the relation between the Wilson lines appearing in the gluon parton distribution function (PDF) and the gluon transverse momentum dependent parton distribution function (TMDPDF). The centrality dependence of the quarkonium nuclear modification factor measured by experiments probes the momentum independent distribution while the transverse momentum dependence and measurements of the azimuthal angular anisotropy may be able to probe the momentum dependent one. We discuss one way to indirectly constrain the quarkonium in-medium real potential by using the factorization formula and lattice calculations. The leading quantum correction to the semiclassical transport equation of quarkonium is also worked out. The study can be easily generalized to quarkonium transport in cold nuclear matter, which is relevant for quarkonium production in eA collisions in the future Electron-Ion Collider.
Heavy Quarkonium Production at LHC through W Boson Decays
The production of the heavy (c{bar c})-quarkonium, (c{bar b})-quarkonium, and (b{bar b})-quarkonium states [({bar Q}') quarkonium for short], via the W{sup +} semi-inclusive decays, has been systematically studied within the framework of the nonrelativistic QCD. In addition to the two color-singlet S-wave states, we also discuss the production of the four color-singlet P-wave states |(Q{bar Q}')({sup 1}P{sub 1}){sub 1}> and |(Q{bar Q}')({sup 3}P{sub J}){sub 1}> [with J = (0,1,2)] together with the two color-octet components |(Q{bar Q}')({sup 1}S{sub 0}){sub 8}> and |(Q{bar Q}')({sup 3}S{sub 1}){sub 8}>. Improved trace technology is adopted to derive the simplified analytic expressions at the amplitude level, which shall be useful for dealing with the following cascade decay channels. At the LHC with the luminosity L {proportional_to} 10{sup 34} cm{sup -2} s{sup -1} and the center-of-mass energy {radical}S = 14 TeV, sizable heavy-quarkonium events can be produced through the W{sup +} boson decays; i.e., 2.57 x 10{sup 6} {eta}{sub c}, 2.65 x 10{sup 6} J/{Psi}, and 2.40 x 10{sup 6} P-wave charmonium events per year can be obtained, and 1.01 x 10{sup 5} B{sub c}, 9.11 x 10{sup 4} B*{sub c}, and 3.16 x 10{sup 4} P-wave (c{bar b})-quarkonium events per year can be obtained. Main theoretical uncertainties have also been discussed. By adding the uncertainties caused by the quark masses in quadrature, we obtain {Lambda}{sub W{sup +}{yields}(c{bar c})+c{bar s}} = 524.8{sub -258.4}{sup +396.3} KeV, {Lambda}{sub W{sup +}{yields}(c{bar b})+b{bar s}} = 13.5{sub -3.29}{sup +4.73} KeV, {Lambda}{sub W{sup +}{yields}(c{bar b})+c{bar c}} = 1.74{sub -0.73}{sup +1.98} KeV, and {Lambda}{sub W{sup +}{yields}(c{bar b})+c{bar b}} = 38.6{sub -9.69}{sup +13.4} eV.
Quarkonium at the Frontiers of High Energy Physics: A Snowmass White Paper
In this Snowmass White Paper, we discuss physics opportunities involving heavy quarkonia at the intensity and energy frontiers of high energy physics. We focus primarily on two specific aspects of quarkonium physics for which significant advances can be expected from experiments at both frontiers. The first aspect is the spectroscopy of charmonium and bottomonium states above the open-heavy-flavor thresholds. Experiments at e^+ e^- colliders and at hadron colliders have discovered many new, unexpected quarkonium states in the last 10 years. Many of these states are surprisingly narrow, and some have electric charge. The observations of these charged quarkonium states are the first definitive discoveries of manifestly exotic hadrons. These results challenge our understanding of the QCD spectrum. The second aspect is the production of heavy quarkonium states with large transverse momentum. Experiments at the LHC are measuring quarkonium production with high statistics at unprecedented values of p_T. Recent theoretical developments may provide a rigorous theoretical framework for inclusive production of quarkonia at large p_T. Experiments at the energy frontier will provide definitive tests of this framework. Experiments at the intensity frontier also provide an opportunity to understand the exclusive production of quarkonium states.
Quarkonium Physics at a Fixed-Target Experiment Using the LHC Beams
We outline the many quarkonium-physics opportunities offered by a multi-purpose fixed-target experiment using the p and Pb LHC beams extracted by a bent crystal. This provides an integrated luminosity of 0.5 fb{sup -1} per year on a typical 1cm-long target. Such an extraction mode does not alter the performance of the collider experiments at the LHC. With such a high luminosity, one can analyse quarkonium production in great details in pp, pd and pA collisions at {radical}s{sub NN} {approx_equal} 115 GeV and at {radical}s{sub NN} {approx_equal} 72 GeV in PbA collisions. In a typical pp (pA) run, the obtained quarkonium yields per unit of rapidity are 2-3 orders of magnitude larger than those expected at RHIC and about respectively 10 (70) times larger than for ALICE. In PbA, they are comparable. By instrumenting the target-rapidity region, the large negative-x{sub F} domain can be accessed for the first time, greatly extending previous measurements by Hera-B and E866. Such analyses should help resolving the quarkonium-production controversies and clear the way for gluon PDF extraction via quarkonium studies. The nuclear target-species versatility provides a unique opportunity to study nuclear matter and the features of the hot and dense matter formed in PbA collisions. A polarised proton target allows the study of transverse-spin asymmetries in J/{Psi} and {Upsilon} production, providing access to the gluon and charm Sivers functions.
Quarkonium suppression in strongly coupled plasmas
Suppression of open heavy quarks and quarkonia in heavy-ion collisions are among the most informative probes of quark-gluon plasma (QGP). Interpreting the full wealth of data obtained from the collision events requires a precise theoretical understanding of the evolution of heavy quarks and quarkonia as they propagate through a strongly coupled plasma. Such calculations require the evaluation of a gauge-invariant correlator of chromoelectric fields. This chromoelectric correlator encodes all the characteristics of QGP that the dissociation and recombination dynamics of quarkonium are sensitive to, which is to say can in principle measure. We review its distinctive qualitative features at weak coupling in QCD up to next-to-leading order and at strong coupling in N = 4 SYM using the AdS/CFT correspondence, as well as its formulation in Euclidean QCD. Furthermore, we report on recent progress in applying our results to the calculation of the final quarkonium abundances after propagating through a cooling droplet of QGP, which illustrates how we may learn about QGP from quarkonium measurements. We devote special attention to how the presence of a strongly coupled plasma modifies the transport description of quarkonium, in comparison to approaches that rely on weak coupling approximations to describe quarkonium dissociation and recombination.
Deconfinement as an entropic self-destruction: A solution for the quarkonium suppression puzzle?
The entropic approach to dissociation of bound states immersed in strongly coupled systems is developed. In such systems, the excitations of the bound state are often delocalized and characterized by a large entropy, so that the bound state is strongly entangled with the rest of the statistical system. If this entropy S increases with the separation r between the constituents of the bound state, S=S(r), then the resulting entropic force F=T ∂S/∂r (T is temperature) can drive the dissociation process. As a specific example, we consider the case of heavy quarkonium in strongly coupled quark-gluon plasma, where lattice QCD indicates a large amount of entropy associated with the heavy quark pair at temperatures 0.9T c ≤ T ≤ 1.5T c (T c is the deconfinement temperature); this entropy S(r) grows with the interquark distance r. We argue that the entropic mechanism results in an anomalously strong quarkonium suppression in the temperature range near T c . This entropic self-destruction may thus explain why the experimentally measured quarkonium nuclear modification factor at RHIC (lower energy density) is smaller than at LHC (higher energy density), possibly resolving the “quarkonium suppression puzzle”—all of the previously known mechanisms of quarkonium dissociation operate more effectively at higher energy densities, and this contradicts the data. As a result, we find that near T c the entropic force leads to delocalization of the bound hadron states; we argue that this delocalization may be the mechanism underlying deconfinement.