We present a model to explain the bottomonium suppression in Pb+Pb collisions at mid-rapidity obtained from Large Hadron Collider (LHC) energy, √ sNN = 2.76 TeV. The model consists of two decoupled mechanisms namely, color screening during bottomonium production followed by gluon induced dissociation along with collisional damping. The quasi-particle model (QPM) is used as equation of state (EOS) for the quark-gluon plasma (QGP) medium. The feed-down from higher Υ states, such as Υ(1P ), Υ(2S) and Υ(2P ), dilated formation times for bottomonium states and viscous effect of the QGP medium are other ingredients included in the current formulation. We further assume that the QGP is expanding according to (1+1)-dimensional Bjorken's boost invariant scaling law. The net suppression (in terms of pT integrated survival probability) for bottomonium states at mid rapidity is obtained as a function of centrality and the result is then compared both quantitatively and qualitatively with the recent LHC experimental data in the mid rapidity region recently published by the CMS Collaboration. We find that the current model, based on Debye color screening plus gluonic dissociation along with collisional damping, better describes the centrality dependence of bottomonium suppression at LHC energy as compared to the color screening model alone.

The Euclidean space, obtained by the analytical continuation of time, to an imaginary time, is used to model thermal systems. In this work, it is taken a step further to systems with spatial thermal variation, by developing an equivalence between the spatial variation of temperature in a thermal bath and the curvature of the Euclidean space. The variation in temperature is recast as a variation in the metric, leading to a curved Euclidean space. The equivalence is substantiated by analyzing the Polyakov loop, the partition function and the periodicity of the correlation function. The bulk thermodynamic properties like the energy, entropy and the Helmholtz free energy are calculated from the partition function, for small metric perturbations, for a neutral scalar field. The Dirac equation for an external Dirac spinor, traversing in a thermal bath with spatial thermal gradients, is solved in the curved Euclidean space. The fundamental behavior exhibited by the Dirac spinor eigenstate, may provide a possible mechanism to validate the theory, at a more basal level, than examining only bulk thermodynamic properties. Furthermore, in order to verify the equivalence at the level of classical mechanics, the geodesic equation is analyzed in a classical backdrop. The mathematical apparatus is borrowed from the physics of quantum theory in a gravity-induced spacetime curvature. As spatial thermal variations are obtainable at QCD or QED energies, it may be feasible for the proposed formulation to be validated experimentally.

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 √ s N N = 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 bb pair. We propose a method for determining the temperaturedependent formation time of bottomonia using the solution of the time-independent Schrödinger equation and compare it with another approach based on time-dependent Schrödinger 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 Υ 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.

Recent experimental and theoretical studies suggest that the quarkonia suppression in a thermal QCD medium created at heavy ion collisions is a complex interplay of various physical processes.In this article we put together most of these processes in a unified way to calculate the charmonium survival probability (nuclear modification factor) at energies available at relativistic heavy ion collider (RHIC) and large hadron collider (LHC) experiments. We have included shadowing as the dominant cold nuclear matter (CNM) effect. Further, gluo-dissociation and collision damping have been included which provide width to the spectral function of charmonia in a thermal medium and cause the dissociation of charmonium along with usual colour screening. We include the colour screening using our recently proposed modified Chu and Matsui model. Furthermore, we incorporate the recombination of uncorrelated charm and anti-charm quark for the regeneration of charmonium over the entire temporal evolution of QGP medium. Finally we do the feed-down correction from the excited states to calculate the survival probability of charmonium. We find that our unified model suitably describes the experimental nuclear modification data of J/ψ at RHIC and LHC simultaneously.

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 √ s N N = 2.76, 5.02 TeV, and in p-Pb at √ s N N = 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 QQ 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 part and transverse momentum, p T dependence of ϒ(1S) and ϒ(2S) states suppression in Pb-Pb and p-Pb collisions at mid-rapidity. We compare our model predictions for ϒ(1S) and ϒ(2S) suppression with the corresponding experimental data obtained at the LHC energies. We find that the experimental observations on p t and N part dependent suppression agree reasonably well with our model predictions.