Valid QCD sum rules for vector mesons in nuclear matter

Abstract

QCD sum rules for vector mesons (\ensuremath{\rho}, \ensuremath{\omega}, \ensuremath{\varphi}) in nuclear matter are reexamined with an emphasis on the reliability of various sum rules. Monitoring the continuum contribution and the convergence of the operator product expansion plays a crucial role in determining the validity of a sum rule. The uncertainties arising from less than precise knowledge of the condensate values and other input parameters are analyzed via a Monte Carlo error analysis. Our analysis leaves no doubt that vector-meson masses decrease with increasing density. This resolves the current debate over the behavior of the vector-meson masses and the sum rules to be used in extracting vector meson properties in nuclear matter. We find a ratio of \ensuremath{\rho}-meson masses of ${\mathit{m}}_{\mathrm{\ensuremath{\rho}}}^{\mathrm{*}}$/${\mathit{m}}_{\mathrm{\ensuremath{\rho}}}$=0.78\ifmmode\pm\else\textpm\fi{}0.08 at nuclear matter saturation density.