Low-mass vector-meson production at forward rapidity in p0p and Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$~GeV

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low-mass vector-meson ($\omega +\rho$ and $\phi$) production through the dimuon decay channel at forward rapidity $(1.2<\mathrm{\mid }y\mathrm{\mid }<2.2)$ in $p$$+$$p$ and Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$~GeV. The low-mass vector-meson yield and nuclear-modification factor were measured as a function of the average number of participating nucleons, $⟨N_{\mathrm{p}\mathrm{a}\mathrm{r}\mathrm{t}}⟩$, and the transverse momentum $p_T$. These results were compared with those obtained via the kaon decay channel in a similar $p_T$ range at midrapidity. The nuclear-modification factors in both rapidity regions are consistent within the uncertainties. A comparison of the $\omega +\rho$ and $J\mathrm{/}\psi$ mesons reveals that the light and heavy flavors are consistently suppressed across both $p_T$ and $⟨N_{\mathrm{p}\mathrm{a}\mathrm{r}\mathrm{t}}⟩$. In contrast, the $\phi$ meson displays a nuclear-modification factor consistent with unity, suggesting strangeness enhancement in the medium formed.