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

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

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

Authors

Zschocke, S.

Pavlenko, O. P.

Kampfer, B.

Description

Within the Borel QCD sum rule approach at finite baryon density we study the role of the four-quark condensates for the modifications of the vector mesons $ρ$, $ω$ and $ϕ$ in nuclear matter. We find that in-medium modifications of the $ρ$ and $ω$ mesons are essentially dominated by the dependence of the 4-quark condensate on the nucleon density. In particular, the numerical value of a parameter ($κ_N$), which describes the strength of the density dependence of the 4-quark condensate beyond the mean-field approximation, governs the decrease of the $ρ$ mass as a function of the density. For the $ω$ meson the sign of the in-medium mass shift is changed by variations of $κ_N$. To study consistently the in-medium broadening of the light vector mesons we employ $ρN$ and $ωN$ scattering amplitudes derived recently from a covariant unitary coupled channel approach adjusted to pion- and photo-induced reactions. In contrast to the $ρ$ and $ω$ mesons, the in-medium mass of the $ϕ$ 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.