QCD sum rules for vector mesons in the nuclear medium

Abstract

A consistent treatment of quantum chromodynamical (QCD) sum rules in the nuclear medium is developed. Its close relation to the structure functions of the nucleon in the deep inelastic scattering is emphasized. The formalism is applied to the spectral changes of vector mesons (\ensuremath{\rho}, \ensuremath{\omega}, and \ensuremath{\varphi}) in the nuclear matter. A linear decrease of the masses as a function of density is found. The four-quark condensate 〈(q\ifmmode\bar\else\textasciimacron\fi{}q${)}^{2}$〉 and a twist-two condensate 〈q\ifmmode\bar\else\textasciimacron\fi{}${\ensuremath{\gamma}}_{\mathrm{\ensuremath{\mu}}}$q${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}_{\mathrm{\ensuremath{\mu}}}$${\mathit{D}}_{\ensuremath{\nu}}$q〉 in medium play dominant roles for the mass-shift of light mesons. Physical implications of the result in finite nuclei and in heavy ion collisions are also discussed.