6,735 research outputs found
Role of current quark mass dependent multi-quark interactions in low lying meson mass spectra
We call attention to a class of current-quark mass dependent multi-quark
interaction terms which break explicitly the chiral and
symmetries. They complete the set of effective quark interactions that
contribute at the same order in as the 't Hooft flavor determinant
interaction and the eight quark interactions in the phase of spontaneously
broken chiral symmetry. The classification scheme matches the counting
rules based on arguments set by the scale of spontaneous chiral symmetry
breaking. Together with the leading in four quark Nambu-Jona-Lasinio
Lagrangian and current quark mass matrix, the model is apt to account for the
correct empirical ordering and magnitude of the splitting of states in the low
lying mass spectra of spin zero mesons. The new terms turn out to be essential
for the ordering in the pseudoscalar sector and for the scalars.Comment: 6 pages, 1 figure, prepared for the proceedings of the workshop
"Excited QCD 2013", 03-09 February 2013 in Bjelasnica Mountain, Sarajevo,
Bosni
Eta invariants for flat manifolds
Using H. Donnelly result from the article "Eta Invariants for G-Spaces" we
calculate the eta invariants of the signature operator for almost all
7-dimensional flat manifolds with cyclic holonomy group. In all cases this eta
invariants are an integer numbers. The article was motivated by D. D. Long and
A. Reid article "On the geometric boundaries of hyperbolic 4-manifolds, Geom.
Topology 4, 2000, 171-178Comment: 18 pages, a new version with referees comment
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