3,470 research outputs found
Infrared-Improved Soft-wall AdS/QCD Model for Mesons
We construct and investigate an infrared-improved soft-wall AdS/QCD model for
mesons. Both linear confinement and chiral symmetry breaking of low energy QCD
are well characterized in such an infrared-improved soft-wall AdS/QCD model.
The model enables us to obtain a more consistent numerical prediction for the
mass spectra of resonance scalar, pseudoscalar, vector and axial-vector mesons.
In particular, the predicted mass for the lightest ground state scalar meson
shows a good agreement with the experimental data. The model also provides a
remarkable check for the Gell-Mann-Oakes-Renner relation and a sensible result
for the space-like pion form factor.Comment: 15 pages, 4 figures, 7 tables, published versio
Potentials for soft wall AdS/QCD
Soft-wall models in AdS/QCD generally have dilaton and scalar fields that
vary with the fifth-dimension coordinate. These fields can be parameterized to
yield hadron mass spectra with linear radial trajectories and to incorporate
spontaneous breaking of chiral symmetry. We show how to construct scalar
potentials which lead to such solutions.Comment: 21 pages. Version 3 matches that accepted for publication. Typos have
been corrected and references added. Substantial discussion has been added in
order to clarify our approach and the issue of the dilaton mass in Sec. 4.
Central results and conclusions remain unchanged
On the Lichnerowicz conjecture for CR manifolds with mixed signature
We construct examples of nondegenerate CR manifolds with Levi form of
signature , , which are compact, not locally CR flat, and
admit essential CR vector fields. We also construct an example of a noncompact
nondegenerate CR manifold with signature which is not locally CR flat
and admits an essential CR vector fields. These provide counterexamples to the
analogue of the Lichnerowicz conjecture for CR manifolds with mixed signature.Comment: 7 page
Effective Action for Non-Geometric Fluxes from Duality Covariant Actions
The (heterotic) double field theories and the exceptional field theories are
recently developed for manifestly duality covariant formulation of various
supergravity theories, describing low-energy limit of various (heterotic)
superstring and M-theory compactifications. These field theories are known to
be reduced to the standard descriptions by introducing appropriately
parameterized generalized metric and by applying suitably chosen section
conditions. We generalize this development to non-geometric backgrounds by
utilizing dual fields pertinent to non-geometric fluxes. We introduce different
parameterizations for the generalized metric, in terms of the conventional
supergravity fields or the dual fields. Under certain simplifying assumptions,
we construct new effective action for non-geometric backgrounds. We then obtain
the non-geometric backgrounds sourced by exotic branes. From them, we construct
their -duality monodromy matrices. The charge of exotic branes obtained from
these monodromy matrices agrees perfectly with the charge obtained from the
non-geometric flux integral.Comment: cover + 101 pages; v2. published version in JHE
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