Speaker
Description
The matter produced in an ultra-relativistic heavy-ion collision, dubbed as the QGP, posses a temperature $10^5$ times that of Sun's core and survives for a very short time ($10^{-22}$ s), producing thousands of particles which exhibit collective motion described by some global observables, e.g. charged particle multiplicity($N_{ch}$), mean transverse momentum per particle ($[p_T]$), harmonic flow ($V_n$) etc. Fluctuations and correlations between these observables contain crucial information of the QGP medium as well as of the nuclear properties. We study in hydrodynamic model $p_T$-dependent event-by-event fluctuation of $V_n$ probed by the factorization breaking coefficient, which shows decorrelation at higher $p_T$-bins. We study the fluctuation of $[p_T]$ in ultra-central Pb+Pb collision and explain the sudden fall in the ATLAS data over a narrow range of multiplicity. We show in our model that this sharp fall is a consequence of the underlying thermalization assumption of the system. We also study the observable $v_0(p_T)$, first introduced by Teaney et al., which is similar to anisotropic flow in terms of its collective nature and, it correlates the spectra with the event-by-event mean transverse momentum per particle ($[p_T]$). We present model predictions for charged and identified particles. Additionally, we show how $v_0(p_T)$ can be used to capture the $p_T$-acceptance effect of different collective observables. Through these above-mentioned studies, we present an overall picture how correlations and fluctuations of the collective observables can be used to study the dynamics and properties of the QGP medium.
