Orateur
Description
Production of $\phi(1020)$ mesons is expected to play an important role in studies of the transition from confined to deconfined matter. With its zero net strangeness and its valence structure composed predominantly of $s$ and $\bar{s}$ valence quarks, the $\phi$ meson should not be sensitive to strangeness-related effects in a purely hadronic scenario, but will behave like a doubly-strange particle once partonic degrees of freedom are significant. At the CERN SPS, the energy dependence of the $\phi$ rapidity distribution is known to display a puzzling behavior. In $p+p$ interactions, the width $\sigma_y$ of the $\phi$ rapidity spectrum follows a trend similar to that of other particles(i.e., $\pi^\pm$, $K^\pm$, and $\bar{\Lambda}$ in both $p+p$ and Pb+Pb collisions), while for central Pb+Pb reactions, it displays a much faster increase as a function of collision energy (EPJC 80, 2020, 199). No information on this phenomenon in any intermediate-size system was available up to now.
In this talk, first results on $\phi$ meson production in central $^{40}$Ar+$^{45}$Sc collisions are presented. These are obtained through the $\phi \rightarrow K^+K^-$ decay channel using the $tag-and-probe$ method adapted from LHCb and ATLAS experiments. The $p_T$-integrated rapidity distributions, total $\phi$ multiplicities and hidden strangeness over pion ($\phi/\pi$) ratios are shown as a function of collision energy and system size from $p+p$ up to central Pb+Pb reactions. The puzzling energy dependence of $\sigma_y$, and the comparison between $\phi$ and kaon production including STAR and ALICE data on $p+p$, $d+$Au, Cu+Cu, Au+Au, and Pb+Pb reactions will be explicitly addressed in the talk.
