Charged Meson Rapidity Distributions in CentralAu+AuCollisions atsNN=200GeV

We have measured rapidity densities $dN/dy$ of ${\pi }^{\pm }$ and $K^{\pm }$ over a broad rapidity range ($-0.1<y<3.5$) for central $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$. These data have significant implications for the chemistry and dynamics of the dense system that is initially created in the collisions. The full phase-space yields are $1660\pm 15\pm 133$ (${\pi }^{+}$), $1683\pm 16\pm 135$ (${\pi }^{-}$), $286\pm 5\pm 23$ ($K^{+}$), and $242\pm 4\pm 19$ ($K^{-}$). The systematics of the strange to nonstrange meson ratios are found to track the variation of the baryochemical potential with rapidity and energy. Landau-Carruthers hydrodynamics is found to describe the bulk transport of the pions in the longitudinal direction.