Disentangling stopped proton and inclusive net-proton fluctuations at RHIC

Abstract

The recent results on net-proton and net-charge multiplicity fluctuations from the beam energy scan program at RHIC have drawn much attention to explore the critical point in the QCD phase diagram. Experimentally measured protons contain contribution from various processes such as secondaries from higher mass resonance decay, production process, and protons from the baryon stopping. Further, these contributions also fluctuate from event to event and can contaminate the dynamical fluctuations due to the critical point. We present the contribution of stopped proton and produced proton fluctuations in the net-proton multiplicity fluctuation in \auau collisions measured by STAR experiment at RHIC. The produced net-proton multiplicity fluctuations using cumulants and their ratios are studied as a function collision energies. After removing the stopped proton contribution from the inclusive proton multiplicity distribution, a non-monotonic behavior is even more pronounced in the net-proton fluctuations around \sqsn = 19.6 GeV, both in $S\sigma$ and $\kappa\sigma^2$. The present study will be useful to understand the fluctuations originating due to critical point.