Thomas Hilger

QCD sum rules for D and B mesons in nuclear matter

QCD sum rules for D and B mesons embedded in cold nuclear matter are evaluated. We quantify the mass splitting of D-D and B-B mesons as a function of the nuclear matter density; extrapolated to saturation density it is in the order of 60 and 130 MeV, respectively, driven essentially by the condensates , , and . The poorly known condensate may leave room for an even larger D-D mass splitting. The genuine chiral condensate , amplified by heavy-quark masses, enters the Borel transformed sum rules for the mass splitting beyond linear density dependence. The inclusion of strange quark condensates reveals a numerically smaller and opposite effect for the D{sub s}-D{sub s} mass splitting.

Four-quark condensates in nucleon QCD sum rules

Abstract The in-medium behavior of the nucleon spectral density including self-energies is revisited within the framework of QCD sum rules. Special emphasis is given to the density dependence of four-quark condensates. A complete catalog of four-quark condensates is presented and relations among them are derived. Generic differences of such four-quark condensates occurring in QCD sum rules for light baryons and light vector mesons are discussed.

In-medium operator product expansion for heavy-light-quark pseudoscalar mesons

The operator product expansion (OPE) for heavy-light-quark pseudoscalar mesons (D -mesons and B -mesons) in medium is determined, both for a moving meson with respect to the surrounding medium as well as for a meson at rest. First of all, the OPE is given in terms of normal-ordered operators up to mass dimension 5, and the mass of the heavy quark and the mass of the light quark are kept finite. The Wilson coefficients of such an expansion are infrared (IR) divergent in the limit of a vanishing light-quark mass. A consistent separation of scales necessitates an OPE in terms of non-normal-ordered operators, which implies operator mixing, where the IR-divergences are absorbed into the operators. It is shown that the Wilson coefficients of such an expansion are IR-stable, and the limit of a vanishing light-quark mass is perfomed. Details of the major steps for the calculation of the Wilson coefficients are presented. By a comparison with previous results obtained by other theoretical groups we have found serious disagreements.

In-Medium Modifications of Scalar Charm Mesons in Nuclear Matter

Employing QCD sum rules the in-medium modifications of scalar charm mesons in a cold nuclear matter environment are estimated. The mass splitting of D ⁎ − D ¯ ⁎ is quantified.

QCD sum rules for D mesons in dense and hot nuclear matter

Open charm mesons (pseudo-scalar and scalar as well as axial-vector and vector) propagating or resting in nuclear matter display an enhanced sensitivity to the chiral condensate. This offers new prospects for seeking signals of chiral restoration, in particular in pA and reactions as envisaged in first-round experiments by the CBM and PANDA collaborations at FAIR. Weinberg-type sum rules for charming chiral partners are presented, and the distinct in-medium modifications of open-charm mesons are discussed. We also address the gluon condensates near Tc and their impact on QCD sum rules.

The impact of chirally odd condensates on the rho meson

Based on QCD sum rules we explore the consequences of a pure chiral restoration scenario for the ρ meson, where all chiral symmetry breaking condensates are dropped whereas the chirally symmetric condensates remain at their vacuum values. This pure chiral restoration scenario causes the drop of the ρ spectral moment by about 120 MeV. The complementarity of mass shift and broadening is discussed. A simple parametrization of the ρ spectral function leads to a width of about 600 MeV if no shift of the peak position is assumed. PACS numbers: 11.30.Rd, 12.38.Lg, 24.85.+p, 14.40.Cs

Wilson coefficients and four-quark condensates in QCD sum rules for medium modifications ofDmesons

Wilson coefficients of light four-quark condensates in QCD sum rules are evaluated for pseudo-scalar

Role of Four-Quark Condensates in QCD Sum Rules

D

In-medium QCD sum rules for D mesons: A projection method for higher order contributions

mesons, thus, pushing the sum rules toward mass dimension six. Contrary to the situation for

Chiral-partner D mesons in a heat bath within QCD sum rules

\bar{q}q