Speaker
Description
Measurements of light hadron production provide essential insight into final-state effects in ultrarelativistic nuclear collisions. These effects include collective flow in both small and large systems, hadronization via recombination, strangeness enhancement, and modifications arising from cold nuclear matter. Studies of system-size and centrality dependence further constrain the role of initial conditions, such as nuclear overlap geometry and nuclear modification of parton distribution functions.
In this talk, we present recently finalized PHENIX measurements of identified charged hadrons ($\pi/K/p$) and vector mesons, including $\omega$, $\rho$, $K^*$ and $\phi$, in p+p, p+Al, p/d/$^3$He/Cu+Au, Au+Au, and U+U collisions at $\sqrt{s_{NN}}$ = 193–200 GeV. Particular emphasis is placed on the $\phi$ meson, a pure $s\bar{s}$ state, which serves as a sensitive probe of strangeness production, parton energy loss, and recombination mechanisms in the quark–gluon plasma (QGP). Using the $\phi\rightarrow\mu\mu$ decay channel, we report the first measurements of low-mass vector mesons at forward rapidity ($1.2 < |y| < 2.2$) as a function of transverse momentum and the average number of participating nucleons.
While the $\omega$ and $\rho$ mesons exhibit strong suppression across all $p_T$ and centralities, the $\phi$ meson shows distinct behavior, with suppression at high $p_T$ and enhancement at intermediate $p_T$ in central collisions. Comparisons to empirical scaling trends, previous measurements, and theoretical model calculations are discussed, providing new constraints on the flavor dependence of particle production and the interplay of cold and hot nuclear matter effects in heavy-ion collisions.