Impact of the QCD four-quark condensate on in-medium spectral changes of light vector mesons


Impact of the QCD four-quark condensate on in-medium spectral changes of light vector mesons

Zschocke, S.; Pavlenko, O. P.; Kämpfer, B.

Within the Borel QCD sum rule approach at finite baryon density we study the role of the four-quark condensates % such as langle(overline{q} gamma_{mu} lambda^a)^2rangle_n , for the modifications of the vector mesons rho, omega and phi in nuclear matter.
We find that in-medium modifications of the rho and omega mesons are essentially dominated by the dependence of the 4-quark condensate on the nucleon density. In particular, the numerical value of a parameter (kappa_N), which describes the strength of the density dependence of the 4-quark condensate beyond the mean-field approximation, governs the decrease of the rho mass as a function of the density. For the omega meson the sign of the in-medium mass shift is changed by variations of kappa_N. To study consistently the in-medium broadening of the light vector mesons we employ rho N and omega N scattering amplitudes derived recently from a covariant unitary coupled channel approach adjusted to pion- and photo-induced reactions. In contrast to the rho and omega mesons, the in-medium mass of the phi meson is directly related to the chiral (strange) quark condensate. Measurements of the vector meson spectral change in heavy-ion collisions with HADES can shed light on the yet unknown density dependence of the 4-quark condensate.

Keywords: medium modifications; vector mesons; condensates

  • hep-ph/0308070

Permalink: https://www.hzdr.de/publications/Publ-5657
Publ.-Id: 5657