Bottomonium Suppression Research Articles

Bottomonium suppression from the three-loop QCD potential

We compute the suppression of bottomonium in the quark-gluon plasma using the three-loop QCD static potential. The potential describes the spin-averaged bottomonium spectrum below threshold with a less than 1% error. Within potential nonrelativistic quantum chromodynamics and an open quantum systems framework, we compute the evolution of the bottomonium density matrix. The values of the quarkonium transport coefficients are obtained from lattice QCD measurements of the bottomonium in-medium width and thermal mass shift; we additionally include for the first time a vacuum contribution to the dispersive coefficient γ. Using the three-loop potential and the values of the heavy quarkonium transport coefficients, we find that the resulting bottomonium nuclear modification factor is consistent with experimental observations, while at the same time reproducing the lattice measurements of the in-medium width. Published by the American Physical Society 2024

Bottomonium suppression at RHIC and LHC in an open quantum system approach

Bottomonium suppression at RHIC and LHC in an open quantum system approach

Correction to: Bottomonium suppression in heavy-ion collisions and the in-medium strong force

Correction to: Bottomonium suppression in heavy-ion collisions and the in-medium strong force

Bottomonium suppression in heavy-ion collisions and the in-medium strong force

Bottomonium suppression in heavy-ion collisions and the in-medium strong force

Impact of fluctuating initial conditions on bottomonium suppression in 5.02 TeV heavy-ion collisions

We compute bottomonium suppression and elliptic flow within the pNRQCD effective field theory using an open quantum systems approach. For the hydrodynamical background, we use 2+1D MUSIC second-order viscous hydrodynamics with IP-Glasma initial conditions and evolve bottom/antibottom quantum wave packets in real time in these backgrounds. We find that the impact of fluctuating initial conditions is small when compared to results obtained using smooth initial conditions. Including the effect of fluctuating initial conditions, we find that the Upsilon(1S) integrated elliptic flow is v_2[1S] = 0.005 +/- 0.002 +/- 0.001, with the first and second variations corresponding to statistical and systematic theoretical uncertainties, respectively.

Bottomonium Suppression in the Quark–Gluon Plasma — From Effective Field Theories to Non-unitary Quantum Evolution

Bottomonium Suppression in the Quark–Gluon Plasma — From Effective Field Theories to Non-unitary Quantum Evolution

Bottomonium suppression and elliptic flow in heavy-ion collisions

In this proceedings contribution I review recent progress concerning the suppression of bottomonium production in the quark-gluon plasma. Making use of open quantum system methods applied to potential non-relativistic quantum chromodynamics one can show that the dynamics of heavy-quarkonium bound states satisfying the scale hierarchy 1/a0 » πT ∼ mD » E obey a Lindblad equation whose solution provides the quantum evolution of the heavy-quarkonium reduced density matrix. To solve the resulting Lindblad equation we use a quantum trajectories algorithm which allows one to include all possible angular momentum states of the quark-antiquark probe in a scalable manner. We solve the Lindblad equation using a tuned 3+1D dissipative hydrodynamics code for the background temperature evolution. We then consider a large number of Monte-Carlo sampled bottomonium trajectories embedded in this background. This allows us to extract the centrality- and pT-dependence of the nuclear suppression factor RAA[Υ] and elliptic flow v2[Υ]. We find good agreement between our model predictions and available √ sNN = 5.02 TeV = 5.02 TeV Pb-Pb collision experimental data from the ALICE, ATLAS, and CMS collaborations.

Non-equilibrium evolution of quarkonium in medium in the open quantum system approach

In this proceedings contribution, I review recent work that aims to provide a more comprehensive and systematic understanding of bottomonium dynamics in the quark-gluon plasma using an open quantum system (OQS) approach that is applied in the framework of the potential non-relativistic QCD (pNRQCD) effective field theory and coupled to realistic hydrodynamical backgrounds that have been tuned to soft hadron observables. I review how the computation of bottomonium suppression can be reduced to solving a Gorini- Kossakowski-Sudarshan-Lindblad (GKSL) equation for the evolution of the bb̅ reduced density matrix, which includes both singlet and octet states plus medium-induced transitions between them at next-to-leading order (NLO) in the binding energy over temperature. Finally, I present comparisons of phenomenological predictions of the NLO OQS+pNRQCD approach and experimental data for bottomonium suppression and elliptic flow in LHC 5.02 TeV Pb-Pb collisions obtained using both smooth and fluctuating hydrodynamic initial conditions.

Bottomonium suppression and flow in heavy-ion collisions

The strong suppression of bottomonia production in ultra-relativistic heavy-ion collisions is a smoking gun for the creation of a deconfined quarkgluon plasma (QGP). In this proceedings contribution, I review recent work that aims to provide a more comprehensive and systematic understanding of bottomonium dynamics in the QGP through the use of pNRQCD and an open quantum systems approach. This approach allows one to evolve the heavyquarkonium reduced density matrix, taking into account non-unitary effective Hamiltonian evolution of the wave-function and quantum jumps between different angular momentum and color states. In the case of a strong coupled QGP in which Ebind ≪ T, mD ≪ 1=a0, the corresponding evolution equation is Markovian and can therefore be mapped to a Lindblad evolution equation. To solve the resulting Lindblad equation, we make use of a stochastic unraveling called the quantum trajectories algorithm and couple the non-abelian quantum evolution to a realistic 3+1D viscous hydrodynamical background. Using a large number of Monte-Carlo sampled bottomonium trajectories, we make predictions for bottomonium RAA and elliptic flow as a function of centrality and transverse momentum and compare to data collected by the ALICE, ATLAS, and CMS collaborations.

Bottomonium suppression in PbPb collisions at energies available at the CERN Large Hadron Collider

High energy collisions are the laboratories within our reach to study strongly interacting matter under extreme temperatures. In the present study, we use a quarkonia suppression scheme to explain the bottomonium production at the two energies available at the CERN Large Hadron Collider. We employ echo-qgp to model the $(3+1)$-dimensional relativistic viscous hydrodynamic evolution of the medium. Bottomonia produced in the early stage dissociates due to color screening, gluonic dissociation, and collisional damping in addition to shadowing as an initial state effect. In the color screening mechanism, the temperature from hydrodynamics is used to find the screening radii at each centrality and rapidity. The shadowing effect utilizes the parton distribution functions obtained from the CT14 global analysis and shadowing factors from EPPS16. A lattice QCD based equation of state from the Wuppertal-Budapest Collaboration has been used. The experimental values of pion $({\ensuremath{\pi}}^{+})$ spectra were used to constrain the initial conditions of the dynamics. The bottomonium suppression is determined as a function of centrality, transverse momentum, and rapidity for $\mathrm{\ensuremath{\Upsilon}}(1S)$ and $\mathrm{\ensuremath{\Upsilon}}(2S)$ states at the LHC energies of 2.76 and $5.02\phantom{\rule{4pt}{0ex}}\mathrm{TeV}$. We find a fairly good agreement between our theoretically calculated survival probability and the measured nuclear modification factor $({R}_{AA})$ at the two energies.

Bottomonium suppression and elliptic flow from real-time quantum evolution

We compute the suppression and elliptic flow of bottomonium using real-time solutions to the Schrödinger equation with a realistic in-medium complex-valued potential. To model the initial production, we assume that, in the limit of heavy quark masses, the wave-function can be described by a lattice-smeared (Gaussian) Dirac delta wave-function. The resulting final-state quantum-mechanical overlaps provide the survival probability of all bottomonium eigenstates. Our results are in good agreement with available data for RAA as a function of Npart and pT collected at sNN=5.02 TeV. In the case of v2 for the various states, we find that the path-length dependence of ϒ(1s) suppression results in quite small v2 for ϒ(1s). Our prediction for the integrated elliptic flow for ϒ(1s) in the 10−90% centrality class is v2[ϒ(1s)]=0.0026±0.0007. We additionally find that, due to their increased suppression, excited bottomonium states have a larger elliptic flow and we make predictions for v2[ϒ(2s)] and v2[ϒ(3s)] as a function of centrality and transverse momentum. Similar to prior studies, we find that it is possible for bottomonium states to have negative v2 at low transverse momentum.

Equation of States and Charmonium Suppression in Heavy-Ion Collisions

The present article is the follow-up of our work Bottomonium suppression in quasi-particle model, where we have extended the study for charmonium states using quasi-particle model in terms of quasi-gluons and quasi quarks/antiquarks as an equation of state. By employing medium modification to a heavy quark potential thermodynamic observables, viz., pressure, energy density, speed of sound, etc. have been calculated which nicely fit with the lattice equation of state for gluon, massless, and as well massive flavored plasma. For obtaining the thermodynamic observables we employed the debye mass in the quasi particle picture. We extended the quasi-particle model to calculate charmonium suppression in an expanding, dissipative strongly interacting QGP medium (SIQGP). We obtained the suppression pattern for charmonium states with respect to the number of participants at mid-rapidity and compared it with the experimental data (CMS JHEP) and (CMS PAS) at LHC energy (Pb+Pb collisions, sNN = 2.76 TeV).

Erratum to: Is bottomonium suppression in proton-nucleus and nucleus-nucleus collisions at LHC energies due to the same effects?

Erratum to: Is bottomonium suppression in proton-nucleus and nucleus-nucleus collisions at LHC energies due to the same effects?

Centrality and transverse momentum dependent suppression of Upsilon (1S) and Upsilon (2S) in p\u2013Pb and Pb\u2013Pb collisions at the CERN Large Hadron Collider

Deconfined QCD matter in heavy-ion collisions has been a topic of paramount interest for many years. Quarkonia suppression in heavy-ion collisions at the relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) experiments indicate the quark-gluon plasma (QGP) formation in such collisions. Recent experiments at LHC have given indications of hot matter effect in asymmetric p–Pb nuclear collisions. Here, we employ a theoretical model to investigate the bottomonium suppression in Pb–Pb at sqrt{s_{NN}}=2.76, 5.02 TeV, and in p–Pb at sqrt{s_{NN}}=5.02 TeV center-of-mass energies under a QGP formation scenario. Our present formulation is based on an unified model consisting of suppression due to color screening, gluonic dissociation along with the collisional damping. Regeneration due to correlated Qbar{Q} pairs has also been taken into account in the current work. We obtain here the net bottomonium suppression in terms of survival probability under the combined effect of suppression plus regeneration in the deconfined QGP medium. We mainly concentrate here on the centrality, N_text {part} and transverse momentum, p_{T} dependence of Upsilon (1S) and Upsilon (2S) states suppression in Pb–Pb and p–Pb collisions at mid-rapidity. We compare our model predictions for Upsilon (1S) and Upsilon (2S) suppression with the corresponding experimental data obtained at the LHC energies. We find that the experimental observations on p_t and N_text {part} dependent suppression agree reasonably well with our model predictions.

Bottomonium suppression at RHIC and LHC

The strong suppression of heavy quarkonia is a good indicator that one has generated a quark-gluon plasma (QGP) in an ultrarelativistic heavy ion collision. Recent advancements in first principles calculations of the heavy quark potential provide additional insight into this suppression and can be used to further pin down the in-medium properties of the QGP. Realistic 3+1d dissipative hydrodynamical models can be used to simulate the QGP and, with bottomonium as a probe, one can make inferences for the initial temperature of the QGP and other phenomenological parameters such as the shear viscosity to entropy density ratio. However, progressing to LHC sNN=5.02TeV Pb-Pb collisions, one expects regeneration to have an increasingly important impact on the suppression observables. In this proceedings, we present a brief overview to set up the model and then provide model results for bottomonium suppression and regeneration, for ultrarelativistic heavy-ion collision experiments at RHIC and LHC.

Is bottomonium suppression in proton-nucleus and nucleus-nucleus collisions at LHC energies due to the same effects?

We show that we can reproduce all the features of the bottomonium suppression in both proton-nucleus and nucleus-nucleus collisions at LHC energies in a comover-interaction picture. For each collision system, we use the measured relative suppression of the excited ϒ(2S) and ϒ(3S) states to ϒ(1S) by ATLAS and CMS to parametrise the scattering cross sections of all S- and P -wave bottomonia with the comoving particles created during the collisions. In addition to a single nonperturbative parameter, these cross sections depend on the momentum distribution of these comovers which we found to be the same for proton-nucleus and nucleus-nucleus collisions as well as for partonic and hadronic comovers. Moreover, we can also reproduce the absolute suppresion rates measured by ALICE, ATLAS, CMS and LHCb when the nuclear modifications of the parton densities are taken into account.

Bottomonium Suppression in Nucleus-Nucleus Collisions Using Effective Fugacity Quasi-Particle Model

We have studied the equation of state and dissociation temperature of bottomonium state by correcting the full Cornell potential in isotropic medium by employing the effective fugacity quasi-particle Debye mass. We had also calculated the bottomonium suppression in an expanding, dissipative strongly interacting QGP medium produced in relativistic heavy-ion collisions. Finally we compared our results with experimental data from RHIC 200GeV/nucleon Au-Au collisions, LHC 2.76 TeV/nucleon Pb-Pb, and LHC 5.02 TeV/nucleon Pb-Pb collisions as a function of number of participants.

Bottomonium suppression using a lattice QCD vetted potential

We estimate bottomonium yields in relativistic heavy-ion collisions using a lattice QCD vetted, complex-valued, heavy-quark potential embedded in a realistic, hydrodynamically evolving medium background. We find that the lattice-vetted functional form and temperature dependence of the proper heavy-quark potential dramatically reduces the dependence of the yields on parameters other than the temperature evolution, strengthening the picture of bottomonium as QGP thermometer. Our results also show improved agreement between computed yields and experimental data produced in RHIC 200 GeV/nucleon collisions. For LHC 2.76 TeV/nucleon collisions, the excited states, whose suppression has been used as a vital sign for quark-gluon-plasma production in a heavy-ion collision, are reproduced better than previous perturbatively-motivated potential models; however, at the highest LHC energies our estimates for bottomonium suppression begin to underestimate the data. Possible paths to remedy this situation are discussed.

Complex potential and bottomonium suppression at LHC energy

We have studied the thermal suppression of the bottomonium states in relativistic heavy-ion collision at LHC energies as function of centrality, rapidity, transverse momentum. First, we address the effects of the nonperturbative confining force and the momentum anisotropy together on heavy quark potential at finite temperature, which are resolved by correcting both the perturbative and nonperturbative terms of the potential at T = 0 in a weakly-anisotropic medium, not its perturbative term alone as usually done in the literature. Second, we model the expansion of medium by the Bjorken hydrodynamics in the presence of both shear and bulk viscosity, followed by an additional pre-equilibrium anisotropic evolution. Finally, we couple them together to quantify the yields of bottomonium production in nucleus–nucleus collisions at LHC energies and found a better agreement with the CMS data. Our estimate of the inclusive ϒ(1S) production indirectly constrains both the uncertainties in isotropization time and the shear-to-entropy density ratio and favors the values as 0.3 fm/c and 0.3 (perturbative result), respectively.

Temperature-dependent formation-time approach forΥsuppression at energies available at the CERN Large Hadron Collider

We present here a comprehensive model to describe the bottomonium suppression data obtained from the CERN Large Hadron Collider (LHC) at center-of-mass energy of $\sqrt{s_{NN}}=2.76$ TeV. We employ a quasiparticle model (QPM) equation of state for the quark-gluon plasma (QGP) expanding under Bjorken's scaling law. The current model includes the modification of the formation time based on the temperature of the QGP, color screening during bottomonium production, gluon induced dissociation and collisional damping due to the imaginary part of the potential between the $b\bar b$ pair. We propose a method for determining the temperature-dependent formation time of bottomonia using the solution of the time-independent Schr\"{o}dinger equation and compare it with another approach based on time-dependent Schr\"{o}dinger wave equation simulation. We find that these two independent methods based on different axioms give similar results for the formation time. Cold nuclear matter effects and feed-down from higher resonance states of $\Upsilon$ have also been included in the present work. The suppression of the bottomonium states at mid rapidity is determined as a function of centrality. The results compare closely with the recent centrality-dependent suppression data at the energies available at the CERN LHC in the mid rapidity region.