Łukasz Rozpłochowski

arXiv2024

Energy dependence of $ϕ$(1020) meson production in nucleus-nucleus collisions at the CERN SPS

This paper presents preliminary results from the NA61/SHINE experiment on $ϕ$ meson production in central Ar+Sc collisions at beam momenta of 150$A$, 75$A$, and 40$A$ GeV/$c$ (corresponding to $\sqrt{s_{NN}}$ = 16.8, 11.9, and 8.8 GeV, respectively). These results include double differential distributions in rapidity ($y$) and transverse momentum ($p_T$), as well as $p_T$-integrated rapidity distributions and total $ϕ$ yields. Additionally, the widths of the rapidity distributions of $ϕ$ and $ϕ/π$ yield ratios are compared to those from Pb+Pb and \pp reactions. Notably, this work represents the first-ever measurements of $ϕ$ production in a mid-sized system at SPS energies.

nucl-ex↗

arXiv2019

Can pion spectra in Pb+Pb collisions at CERN SPS energies be described by those in p+p reactions and energy-momentum conservation ? Rapidity distributions of pions in p+p and Pb+Pb collisions at CERN SPS energies

The centrality dependence of rapidity distributions of pions in Pb+Pb reactions can be understood by imposing local energy-momentum conservation in the longitudinal "fire-streaks" of excited matter. With no tuning nor adjustment to the experimental data, the rapidity distribution of pions produced by the fire-streak which we obtained from Pb+Pb collisions reproduces the shape of the experimental pion rapidity distribution in p+p interactions, measured by the NA49 Collaboration at the same energy. The observed difference in the absolute normalization of this distribution can be explained by the difference in the overall energy balance, induced by baryon stopping and strangeness enhancement phenomena occurring in heavy ion collisions. We estimate the latter effects using a collection of SPS experimental data on $π^\pm$, $K^\pm$, net $p$, and $n$ production in p+p and Pb+Pb reactions. Implications of the above findings are discussed.

nucl-th↗