Effects of Baryon-Anti-baryon Annihilation on the Anti-hyperon to Anti-proton Ratio in Relativistic Nucleus-Nucleus Collisions

Abstract

RHIC’s Beam Energy Scan Program at lower energy and future facilities at FAIR offer a unique opportunity to study Quark-Gluon Plasma (QGP) at high baryon density. The formation of QGP is often characterized by the enhanced production of strange over non-strange particles in central heavy-ion collisions relative to peripheral or proton-proton collisions at the same energy . Previous measurements at RHICs’ AGS and CERN SPS have presented evidence of strangeness enhancement in the light of non-monotonic variation of kaon-to-pion ratio as a function of collision energy. A similar signature was also observed in the baryon sector, where an enhancement in $\bar{\Lambda }$ to p̄ was reported . However, it still remains unclear whether $\bar{\Lambda }$ to p̄ enhancements can be uniquely attributed to the strangeness enhancement owing to the deconfinement phase transition. In this article, we will demonstrate that processes like baryon-anti-baryon annihilation in the late hadronic stage may also account for the apparent enhancement in $\bar{\Lambda }$ to p̄ ratio.