1,400 research outputs found
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
Radial Excitations of Heavy Mesons
Recent discovery of D_s states suggests existence of radial excitations. Our
semirelativistic quark potential model succeeds in reproducing these staes
within one to two percent of accuracy compared with the experiments, D_s0(2860)
and D_s^*(2715), which are identified as 0^+ and 1^- radial excitations (n=2).
We also present calculations of radial excitations for B/B_s heavy mesons.
Relation between our formulation and the modified Goldberger-Treiman relation
is also described.Comment: 3 pages, 1 figure, QNP06 conference repor
Effective Lagrangian for Two-photon and Two-gluon Decays of -wave Heavy Quarkonium and states
In the traditional non-relativistic bound state calculation, the two-photon
decay amplitudes of the -wave and states depend
on the derivative of the wave function at the origin which can only be obtained
from potential models. However by neglecting the relative quark momenta, the
decay amplitude can be written as the matrix element of a local heavy quark
field operator which could be obtained from other processes or computed with
QCD sum rules technique or lattice simulation. Following the same line as in
recent work for the two-photon decays of the -wave and
quarkonia, we show that the effective Lagrangian for the two-photon decays of
the -wave and is given by the heavy quark
energy-momentum tensor local operator or its trace, the scalar
density and that the expression for two-photon and two-gluon decay
rate is given by the decay constant and is similar to that of
which is given by . From the existing QCD sum rules
value for , we get for the two-photon
width, somewhat larger than measurement, but possibly with large uncertainties.Comment: v3, LaTeX, 5 pages, 1 figure, minor typos corrected, to appear in
Physical Review
Electromagnetic form factors of the (rho) meson in light cone QCD sum rules
We investigate the electromagnetic form factors of the (rho) meson in light
cone QCD sum rules. We find that the ratio of the magnetic and charge form
factors is larger than two at all values of Q^2, (Q^2 >= 0.5 GeV^2). The values
of the individual form factors at fixed values of Q^2 predicted by the light
cone QCD sum rules are quite different compared to the results of other
approaches. These results can be checked in future, when more precise data on
(rho) meson form factors is available.Comment: 12 pages, 6 figures, LaTeX formatte
Semileptonic and nonleptonic decays in three--point QCD sum rules and factorization approach
We analyze the semileptonic transition with , in the framework of the three--point QCD sum rules and the nonleptonic
decay within the QCD factorization approach. We study to
and transition form factors by separating the mixture
of the and states. Using the transition form factors of
the , we analyze the nonleptonic decay. We also
present the decay amplitude and decay width of these decays in terms of the
transition form factors. The branching ratios of these channel modes are also
calculated at different values of the mixing angle and compared
with the existing experimental data for the nonleptonic case.Comment: 28 Pages, 20 Figures and 9 Table
K+ -> pi+ nu nu(bar) and FCNC from non-universal Z' bosons
Motivated by the E787 and E949 result for K+ -> pi+ nu nu(bar) we examine the
effects of a new non-universal right-handed Z' boson on flavor changing
processes. We place bounds on the tree-level FCNC from K-K(bar) and B-B(bar)
mixing as well as from the observed CP violation in kaon decay. We discuss the
implications for K -> pi nu nu(bar), B -> X nu nu(bar) and B -> tau+ tau-. We
find that existing bounds allow substantial enhancements in the K+ -> pi+ nu
nu(bar) rate, particularly through a new one-loop Z' penguin operator.Comment: Typos corrected, references added, version to appear in PR
Magnetic Moments of Heavy Baryons in Light Cone QCD Sum Rules
The magnetic moments of heavy baryons containing a single charm or
bottom quark are calculated in the framework of light cone QCD sum rules
method. A comparison of our results with the predictions of the quark models is
presented.Comment: 26 Pages, 8 Figures and 1 Tabl
Semileptonic Decay of and From QCD Sum Rule
We calculate , and to transition form
factors, and study semileptonic decays of and based on QCD sum rule. Measuring these semileptonic decays with
high statistics will give valuable information on the nature of light scalar
mesons.Comment: 13 pages, 5 figures,latex,typos and errors correcte
Pseudoscalar--meson decuplet--baryon coupling constants in light cone QCD
Taking into account the breaking effects, the strong coupling
constants of the , and mesons with decuplet baryons are
calculated within light cone QCD sum rules method. It is shown that all
coupling constants, even in the case of breaking, are described in
terms of only one universal function. It is shown that for transition violation of symmetry is very large
and for other channels when symmetry is violated, its maximum value
constitutes .Comment: 17 Pages, one Figure and 3 Table
Global duality in heavy flavor hadronic decays
We show that heavy meson hadronic decay widths satisfy quark-hadron duality
when smeared over the heavy quark mass, M, to an accuracy of order 1/M^2.Comment: 11 pages, 3 figs, revte
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