Transverse Momentum Distribution of kaons, pions, and (anti-)protons production in U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV using the UrQMD Model

TL;DR

This study uses the UrQMD model to analyze transverse momentum spectra of kaons, pions, and protons in uranium-uranium collisions at 193 GeV, highlighting the impact of nuclear deformation and different simulation modes.

Contribution

First comprehensive analysis of U+U collision dynamics at RHIC energies using UrQMD, comparing cascade and SM-EoS modes across multiple observables.

Findings

Collision dynamics are highly sensitive to uranium nuclear deformation.

Cascade mode better describes low-$p_{T}$ regions, while SM-EoS mode suits high-$p_{T}$ regions.

Particle-antiparticle ratios near unity indicate dominant pair production.

Abstract

In this study, we investigate the transverse momentum spectra of $K ^{\pm }$, $\pi ^{\pm }$ and $p(\bar{p})$ in mid-rapidity ($\left | y \right | < 0.1$) for nine centrality classes ranging from $0\%$ to $80\%$ in $^{238} U$+$^{238} U$ collisions at $\sqrt{s_{NN}}$=193 GeV. The simulations are performed using the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, specifically employing both the cascade mode and the soft momentum-dependent equation of state (SM-EoS) mode. Additionally, we extract other observables from the $p_{T}$ spectrum, including the average transverse momentum ($\left \langle p_{T} \right \rangle$), the particle yield ($dN/dy$) and particle-type ratios, presenting them as a function of collision centrality. We find that the collision dynamics are significantly sensitive to the prolate deformation of the uranium nuclei, which influences the initial geometry and subsequent particle production. We find that the U+U collision dynamics are highly sensitive to the deformation of the uranium nucleus. Consequently, the cascade mode is more appropriate for describing the low-$p_{T}$ region ($p_{T} < 1.2 GeV/c$), while the SM-EoS mode better captures the trends in the high-$p_{T}$ region ($p_{T} > 1.2 GeV/c$). Furthermore, at RHIC energies, our results indicate that pair production is the dominant mechanism for particle creation in the mid-rapidity region. This conclusion is corroborated by the particle-to-antiparticle production ratio, which approaches unity-indicating a high degree of matter-antimatter symmetry in the observed collision events.