3,377 research outputs found
QCD Interactions of Heavy Mesons with Pions by Light-Cone Sum Rules
Light-cone QCD sum rules are employed to compute the strong coupling
constants: g_{B^* B^* pi}, g_{B_1 B_0 pi} and g_{B_1 B^* pi}, where (B,B^*) and
(B_0,B_1) are negative and positive parity (0^-,1^-) and (0^+,1^+) \bar qQ
doublets. The couplings are calculated both for finite values of the heavy
quark mass and in the infinite heavy quark mass limit, deriving sum rules for
m_Q \to \infty.Comment: Latex, 23 pages, 6 figures. Revised version to appear in Z. Phys.
On three-body decays and couplings of heavy mesons to light pseudoscalar mesons
We analyze the decay modes and and, using the available experimental data, we find bounds for the
constants g and h describing the strong coupling of heavy mesons to light
pseudoscalar mesons. Both the decay channels are dominated by broad L=1 charm
resonances; the dominance is effective also in and .Comment: LaTex, 16 pages, 5 figure
decays in the standard model and in scenarios with universal extra dimensions
We study the radiative decays, which are
important to investigate CP violation, and are also relevant to assess the role
of the exclusive modes induced by the transition to saturate
the inclusive decay rate. Moreover, these channels do not
display the same hierarchy as modes, for which the
decay into is enhanced with respect to one into . The
three-body radiative decays reverse the role: we find that this experimentally
observed behavior (although affected by a large uncertainty in the case of the
) is reproduced in the theoretical analysis. We compute a form factor, needed for this study, using light cone QCD sum rules, and
discuss a relation expected to hold in the large energy limit for the light
meson. Finally, we examine in two extensions of the
standard model with universal extra dimensions, to investigate the sensitivity
of this rare mode to such a kind of new physics effects.Comment: RevTeX, 17 pages, 7 figures. High resolution figures available upon
request. Matches the published versio
On thermalization of a boost-invariant non Abelian plasma
Using a holographic method, we further investigate the relaxation towards the
hydrodynamic regime of a boost-invariant non-Abelian plasma taken
out-of-equilibrium. In the dual description, the system is driven
out-of-equilibrium by boundary sourcing, a deformation of the boundary metric,
as proposed by Chesler and Yaffe. The effects of several deformation profiles
on the bulk geometry are investigated by the analysis of the corresponding
solutions of the Einstein equations. The time of restoration of the
hydrodynamic regime is investigated: setting the effective temperature of the
system at the end of the boundary quenching to MeV, the
hydrodynamic regime is reached after a lapse of time of (1 fm/c).Comment: 24 pages, 11 figures. Improved numerical analysis, one more appendix,
two new figures. To appear in JHE
Puzzles in charm spectroscopy
We briefly analyze aspects of open and hidden charm resonances, discussing in
particular the mesons and X(3872).Comment: 8 pages, 4 figures. Invited talk given at the YKIS Seminar on New
Frontiers in QCD: Exotic Hadrons and Hadronic Matter, Kyoto, Japan, 20 Nov. -
8 Dec. 200
Radiative transitions of and
We study radiative decays of and using
light-cone QCD sum rules. In particular, we consider the decay modes
and and evaluate the hadronic parameters in the transition
amplitudes analyzing correlation functions of scalar, pseudoscalar, vector and
axial-vector quark currents. In the case of
we also consider determinations based on two different correlation functions in
HQET. The decay widths turn out to be different than previous estimates
obtained by other methods; the results favour the interpretation of
and as ordinary mesons.Comment: RevTex, 23 pages, 9 eps figure
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