Charged Meson Rapidity Distributions in Central<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Au</mml:mi><mml:mo>+</mml:mo><mml:mi>Au</mml:mi></mml:math>Collisions at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:msub><mml:mi>s</mml:mi><mml:mrow><mml:mi>N</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:msub></mml:msqrt><mml:mo>=</mml:mo><mml:mn>200</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>GeV</mml:mi></mml:math>

Abstract

We have measured rapidity densities $dN/dy$ of ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ and ${K}^{\ifmmode\pm\else\textpm\fi{}}$ over a broad rapidity range ($\ensuremath{-}0.1&lt;y&lt;3.5$) for central $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=200\text{ }\text{ }\mathrm{GeV}$. 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 $1660\ifmmode\pm\else\textpm\fi{}15\ifmmode\pm\else\textpm\fi{}133$ (${\ensuremath{\pi}}^{+}$), $1683\ifmmode\pm\else\textpm\fi{}16\ifmmode\pm\else\textpm\fi{}135$ (${\ensuremath{\pi}}^{\ensuremath{-}}$), $286\ifmmode\pm\else\textpm\fi{}5\ifmmode\pm\else\textpm\fi{}23$ (${K}^{+}$), and $242\ifmmode\pm\else\textpm\fi{}4\ifmmode\pm\else\textpm\fi{}19$ (${K}^{\ensuremath{-}}$). 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.