Dynamics of identified particles production in oxygen–oxygen collisions at \(\sqrt{s_{\textrm{NN}}}=7\) TeV using EPOS4

Abstract

The Large Hadron Collider (LHC) aims to inject oxygen (¹⁶O) ions in the next run into its experiments. This include the anticipated one-day physics run focusing on \({O+O}\,\)collisions at center-of-mass energy \(\sqrt{s_{\textrm{NN}}}=7\) TeV . In this study, we have used recently developed version of the EPOS (EPOS4) to study the production of identified particles (\(\pi ^\pm \), \(K^\pm \) and \(p({\overline{p}})\)) in \({O+O}\,\)collisions at \(\sqrt{s_{\textrm{NN}}}=7\) TeV . Predictions of transverse momentum (\({p_{\textrm{T}}}\,\)) spectra, \({\langle p_{\textrm{T}} \rangle }\,\), integrated yield (\({{\mathrm d}N{/}{\mathrm d}{\textit{y}}}\,\)) for different centrality classes are studied. To provide insight into the collective nature of the produced particles, we look into the \({p_{\textrm{T}}}\,\)-differential particle ratios (\(K/\pi \) and \(p/\pi \)) and \({p_{\textrm{T}}}\,\)-integrated particle ratios to (\(\pi ^++\pi ^-\)) as a function of charge particle multiplicity. The shape of the charge particle multiplicity (\({\textrm{d}N_\textrm{ch}/\textrm{d}\eta }\,\)) and mean transverse momentum (\({\langle p_{\textrm{T}} \rangle }\,\)) is well described by EPOS4. The predictions for the ratios of \(K/\pi \) and \(p/\pi \) from EPOS4 exhibit a systematic overestimation compared to the trends observed in \({p+p}\,\), \({p+Pb}\,\)and \({Pb+Pb}\,\)systems as a function of charged-particle multiplicity. Interestingly, the \({O+O}\,\)results of \({p_{\textrm{T}}}\,\)-integrated particle ratios shows a clear final state multiplicity overlap with \({p+p}\,\), \({p+Pb}\,\)and \({Pb+Pb}\,\)collisions. EPOS4 does not only mimics signs of collectivity, but embeds collective expansion by construction, since it relies on relativistic hydrodynamics to model the evolution of the so-called core and is one of the suitable candidates to study ultra-relativistic heavy-ion collisions. Furthermore, the foreseen data from \({O+O}\,\)collisions at the LHC, when available, will help to better understand the heavy-ion-like behavior in small systems as well as help to put possible constraints on the model parameters.