The VII-th International Conference on the Initial Stages of High-Energy Nuclear Collisions : Initial Stages 2023

Role of spectator nucleons towards longitudinal evolution of particle production in heavy-ion collisions

Not scheduled

20m

Copenhagen

Poster The initial stages and nuclear structure in heavy-ion collisions

Speakers

Somadutta Bhatta (Stony Brook University (US))Dr Vipul Bairathi (Instituto de Alta Investigacio ́n, Universidad de Tarapaca ́, Chile)

Description

The largest uncertainties in modelling of heavy-ion collisions arise from mechanism of energy deposition in initial state. Most models assume colliding ions as transparent objects, during collision of which, spectators fall at large pseudorapidities and have no correlation to final state particle production close to mid-rapidity. On the other hand, in low energy heavy-ion collisions, the influence of spectators towards overall pseudorapidity distribution of produced particles has been reported. Model studies as well as experimental measurements at LHC have shown a considerable shift in the rapidity of the participant zone arising from initial state participant/spectator number fluctuations even at $\sqrt{s_{NN}}$ = 2.76 TeV. Therefore, it is important to probe the effect of initial state towards the longitudinal distribution of produced particles on an event-by-event basis.

In this work, we will report the measurements of Pearson correlation between number of spectators and final state charged particle multiplicity in different pseudorapidity ($\eta$) regions using A Multi-Phase Transport (AMPT) model for Au+Au collisions at $\sqrt{s_{NN}}=$ 11.5, 27, 200 and 2760 GeV. We will present $\eta$ dependence of the magnitude of Pearson correlation between number of spectators and produced particles. A beam energy dependence of the corrleation will also be presented. This correlation measurement provides a novel method to probe: (1) Fragmentation of nucleus in the initial state, (2) contribution of spectator nucleons towards particle production in heavy-ion collisions, (3) consistent description of particle production mechanism between different $\sqrt{s_{NN}}$. Experimental measurement of this correlation may shed light on effect of interaction between spectators and participants such as shearing in initial state towards final state particle production.