Identified charged-hadron production in p+$Al, $^3$He$+$Au, and Cu$+$Au collisions at $√{s_{NN}}=200$ GeV and in U$+$U collisions at $√{s_{NN}}=193$ GeV

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The PHENIX experiment has performed a systematic study of identified charged-hadron (π^±, K^±, p, p̄) production at midrapidity in p+$Al, $^3$He$+$Au, Cu$+$Au collisions at $√{s_{NN}}=200$ GeV and U$+$U collisions at $√{s_{NN}}=193$ GeV. Identified charged-hadron invariant transverse-momentum ($p_T$) and transverse-mass ($m_T$) spectra are presented and interpreted in terms of radially expanding thermalized systems. The particle ratios of $K/π$ and $p/π$ have been measured in different centrality ranges of large (Cu$+$Au, U$+$U) and small ($p$$+$Al, ³He$+$Au) collision systems. The values of $K/π$ ratios measured in all considered collision systems were found to be consistent with those measured in p+p collisions. However the values of $p/π$ ratios measured in large collision systems reach the values of ≈0.6, which is ≈2 times larger than in p+p collisions. These results can be qualitatively understood in terms of the baryon enhancement expected from hadronization by recombination. Identified charged-hadron nuclear-modification factors (RAB) are also presented. Enhancement of proton RAB values over meson RAB values was observed in central ³He$+$Au, Cu$+$Au, and U$+$U collisions. The proton RAB values measured in p+$Al collision system were found to be consistent with $RAB$ values of $ϕ$, $π^±$, $K^±$, and $π^0$ mesons, which may indicate that the size of the system produced in $p$$+$Al collisions is too small for recombination to cause a noticeable increase in proton production.