In the QGP based threshold model \cite{Blaizot:2000ev,Blaizot:1996nq}, in addition to the normal nuclear absorption, $J/ψ$'s are subjected to an 'anomalous' suppression such that above a threshold density $n_{J/ψ}$, all the $J/ψ$'s are melted. In the threshold model we have analysed the recent PHENIX data on the centrality dependence of $J/ψ$ suppression in Au+Au collisions at RHIC. Feedback from decay of the state $χ$ is accounted for.
$J/ψ$'s are anomalously suppressed above a threshold density, $n_{J/ψ}=3.57\pm 0.17$ $fm^{-2}$. Threshold density for anomalous suppression of the state $χ$ is uncertain to a large extent, $n_χ=0.32 \pm 0.32$ $fm^{-2}$. The fraction $F$ of the state $χ$ can not be determined unambiguously, depending on the nuclear absorption, it can vary from 20% to 40%. We have also predicted for the suppression in Pb+Pb collisions at LHC energy. In central Pb+Pb collisions, $J/ψ$'s are suppressed by a factor of 3-4. Suppression pattern is rather similar to that in Au+Au collisions, if not slighty less in central collisions. Using the PHENIX data on the participant number dependence of the Bjorken energy density, we have also estimated the QGP formation time. For critical temperature $T_c$=192 MeV, estimated QGP formation time ranges between 0.07-0.09 fm/c.
We describe ultra-relativistic heavy ion collisions at RHIC and the LHC with a hybrid model using the IP-Glasma model for the earliest stage and viscous hydrodynamics and microscopic transport for the later stages of the collision. We demonstrate that within this framework the bulk viscosity of the plasma plays an important role in describing the experimentally observed radial flow and azimuthal anisotropy simultaneously. We further investigate the dependence of observables on the temperature below which we employ the microscopic transport description.
We calculate elliptic and triangular flow parameters of thermal photons using an event-by-event hydrodynamic model with fluctuating initial conditions at 200A GeV Au+Au collisions at RHIC and at 2.76A TeV Pb+Pb collisions at the LHC for three different centrality bins. The photon elliptic flow shows strong centrality dependence where $v_2(p_T)$ increases towards peripheral collisions both at RHIC and at the LHC energies. However, the triangular flow parameter does not show significant dependence to the collision centrality. The elliptic as well as the triangular flow parameters found to undere…
We study the radiative correction to $p_\perp$-broadening of a fast quark in a quark-gluon plasma beyond the soft gluon approximation. We find that the radiative contribution to quark $\langle p_\perp^2\rangle$ for RHIC and LHC conditions is negative.
Recently we have proved the factorization of NRQCD S-wave heavy quarkonium production at all orders in coupling constant. In this paper we extend this to prove the factorization of infrared divergences in $χ_{cJ}$ production from color singlet $c{\bar c}$ pair in non-equilibrium QCD at RHIC and LHC at all orders in coupling constant. This can be relevant to study the quark-gluon plasma at RHIC and LHC.
Recently we have proved NRQCD color octet factorization of S-wave and P-wave heavy quarkonia production at all orders in coupling constant in QCD in vacuum at high energy colliders in Eur. Phys. J. C76 (2016) 448 and in arXiv:1807.04722 [hep-ph] respectively. In this paper we extend this to prove NRQCD color octet factorization of P-wave heavy quarkonium production in non-equilibrium QCD at RHIC and LHC at all orders in coupling constant. This proof is necessary to study the quark-gluon plasma 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 visco…
The properties of strange pseudoscalar and vectors mesons as well as strange baryon resonances in dense matter are reviewed. Some open questions on the properties of strange hadrons in medium are addressed, such as the experimental signatures of in-medium effects coming from the hadronic phase on the final observables in heavy-ion collisions for the experimental conditions at SIS, RHIC and LHC energies.
Recently we have proved the NRQCD factorization in heavy quarkonium production at high energy colliders at all orders in coupling constant. In this paper we extend this to non-equilibrium QCD and prove the NRQCD factorization in heavy quarkonium production at all orders in coupling constant in non-equilibrium QCD. This proof is necessary to study heavy quarkonium production from quark gluon plasma at RHIC and LHC.
