The horn in the kaon to pion ratio

TL;DR

This study uses a microscopic model to analyze kaon to pion ratios in heavy ion collisions across various energies, revealing a non-monotonic horn structure under certain initial conditions, aligning with experimental data.

Contribution

It introduces a detailed microscopic approach to explain the energy dependence of kaon to pion ratios, highlighting the impact of initial partonic phases on the horn structure.

Findings

Non-monotonic horn-like structure in $K^+/\pi^+$ ratio with initial partonic phase.

Monotonic increase of $K^+/\pi^+$ ratio with hadronic initial state.

Reproduction of $K^-/\pi^-$ ratios within the same formalism.

Abstract

A microscopic approach has been employed to study the kaon productions in heavy ion collisions. The momentum integrated Boltzmann equation has been used to study the evolution of strangeness in the system formed in heavy ion collision at relativistic energies. The kaon productions have been calculated for different centre of mass energies ($\sqrt{s_{\mathrm {NN}}}$) ranging from AGS to RHIC. The results have been compared with available experimental data. We obtain a non-monotonic horn like structure for $K^+/\pi^+$ when plotted with $\sqrt{s_{\mathrm {NN}}}$ with the assumption of an initial partonic phase beyond a certain threshold in $\sqrt{s_{NN}}$. However, a monotonic rise of $K^+/\pi^+$ is observed when a hadronic initial state is assumed for all $\sqrt{s_{\mathrm {NN}}}$. Experimental values of $K^-/\pi^-$ are also reproduced within the ambit of the same formalism. Results from scenarios where the strange quarks and hadrons are formed in equilibrium and evolves with and without secondary productions have also been presented.