1,902 research outputs found
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
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