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*-bar is quantified.Comment: Talk given at QCD 10, Montpelier, France, 27.06.-05.07.201

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 to seek for signals of chiral restoration, in particular in p-A and p-bar-A 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.Comment: 6 pages, 7 figures, conference proceeding

Four-quark condensates in open-charm chiral QCD sum rules

Recently, in Hilger et al. (2011) [1] QCD sum rules for chiral partners in the open-charm meson sector have been presented at nonzero baryon net density or temperature up to and including mass dimension 5. Referring to this, details concerning the cancelation of infrared divergences are presented and important technical and conceptional ingredients for an incorporation of four-quark condensates beyond factorization and of other mass dimension 6 condensates are collected.Comment: 7 pages, 5 figures, conference proceedin

Reductive chain separation of botulinum A toxin — a prerequisite to its inhibitory action on exocytosis in chromaffin cells

Cleavage of the disulfide bond linking the heavy and the light chains of tetanus toxin is necessary for its inhibitory action on exocytotic release ofcatecholamines from permeabi1ized chromaffin cells [(1989) FEBS Lett. 242, 245-248; (1989) J. Neurochern., in press]. The related botulinum A toxin also consists of a heavy and a light chain linked by a disulfide bond. The actions ofboth neurotoxins on exocytosis were presently compared using streptolysin O-permeabilized bovine adrenal chromaffin cells. Botulinum A toxin inhibited Ca2 +-stimulated catecholamine release from these cells. Addition of dithiothreitollowered the effective doses to values below 5 nM. Under the same conditions, the effective doses of tetanus toxin were decreased by a factor of five. This indicates that the interchain S-S bond of botulinum A toxin must also be split before the neurotoxin can exert its effect on exocytosis

Impact of Four-Quark Condensates on In-Medium Effects of Hadrons

Spectral properties of hadrons in nuclear matter are treated in the framework of QCD sum rules. The influence of the ambient strongly interacting medium is encoded in various condensates. Especially, the structure of different four-quark condensates and their density dependencies in light quark systems are exemplified for the omega meson and the nucleon.Comment: Contribution to Quark Confinement and the Hadron Spectrum VII, 02.-07.09.2006, Ponta Delgada, Portuga

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-bar and B - B-bar mesons as a function of the nuclear matter density; extrapolated to saturation density it is in the order of 60 and 130 MeV driven essentially by the condensates , and . The genuine chiral condensate , amplified by heavy-quark masses, enters the Borel transformed sum rules for the mass splitting beyond linear density dependence. Including strange quark condensates reveals a umerically smaller and opposite effect for the Ds - Ds-bar mass splitting.Comment: 16 pages, 8 figures, to be published; a broader range of condensate values is discussed (v2