307 research outputs found
Description of as a system with the fixed center approximation
We study the system with an aim to describe the
resonance. The chiral unitary approach has achieved success in a description of
systems of the light hadron sector. With this method, the system in
the isospin sector , is found to be a dominant component of the resonance. Therefore, by regarding the system as a cluster,
the resonance, we evaluate the system applying the
fixed center approximation to the Faddeev equations. We construct the
unitarized amplitude using the chiral unitary approach. As a result, we find a
peak in the three-body amplitude around 1739 MeV and a width of about 227 MeV.
The effect of the width of and is also discussed. We
associate this peak to the which has a mass of MeV
and a width of MeV
Flavor Changing Neutral Currents Transition of the to Nucleon in Full QCD and Heavy Quark Effective Theory
The loop level flavor changing neutral currents transitions of the
and are investigated in full
QCD and heavy quark effective theory in the light cone QCD sum rules approach.
Using the most general form of the interpolating current for ,
or , as members of the recently discovered sextet heavy baryons with
spin 1/2 and containing one heavy quark, the transition form factors are
calculated using two sets of input parameters entering the nucleon distribution
amplitudes, namely, QCD sum rules and lattice QCD inputs. The obtained results
are used to estimate the decay rates of the corresponding transitions. Since
such type transitions occurred at loop level in the standard model, they can be
considered as good candidates to search for the new physics effects beyond the
SM.Comment: 18 Pages and 13 Table
Semileptonic to Nucleon Transitions in Full QCD at Light Cone
The tree level semileptonic and
transitions are investigated using the light cone QCD sum rules approach in
full theory. The spin--1/2, baryon with or , is
considered by the most general form of its interpolating current. The time
ordering product of the initial and transition currents is expanded in terms of
the nucleon distribution amplitudes with different twists. Considering two sets
of independent input parameters entering to the nucleon wave functions, namely,
QCD sum rules and Lattice QCD parameters, the related form factors and their
heavy quark effective theory limits are calculated and compared with the
existing predictions of other approaches. It is shown that our results satisfy
the heavy quark symmetry relations for lattice input parameters and b case
exactly and the maximum violation is for charm case and QCD sum rules input
parameters. The obtained form factors are used to compute the transition rates
both in full theory and heavy quark effective theory. A comparison of the
results on decay rate of with those predicted by other
phenomenological methods or the same method in heavy quark effective theory
with different interpolating current and distribution amplitudes of the
is also presented.Comment: 18 Pages and 16 Table
Scalar Quarkonia at Finite Temperature
Masses and decay constants of the scalar quarkonia, with
quantum numbers are calculated in the framework of
the QCD sum rules approach both in vacuum and finite temperature. The masses
and decay constants remain unchanged up to but they start to
diminish with increasing the temperature after this point. At near the critic
or deconfinement temperature, the decay constants reach approximately to 25% of
their values in vacuum, while the masses are decreased about 6% and 23% for
bottom and charm cases, respectively. The results at zero temperature are in a
good consistency with the existing experimental values and predictions of the
other nonperturbative approaches. Our predictions on the decay constants in
vacuum as well as the behavior of the masses and decay constants with respect
to the temperature can be checked in the future experiments.Comment: 12 Pages, 9 Figures and 2 Table
Line shape and probabilities of from the reaction
We have performed a calculation of the , , , components in the wave function of the .
For this we make use of the model to find the coupling of
to these components, that with an elaborate angular momentum algebra can be
obtained with only one parameter. Then we use data for the
reaction, from where we determine a form factor needed in the theoretical frame
work, as well as other parameters needed to evaluate the meson-meson selfenergy
of the . Once this is done we determine the probability to
still have a vector core and the probability to have the different meson
components. We find about , and the individual meson-meson
components are rather small, providing new empirical information to support the
largely component of vector mesons, and the in
particular.Comment: 30 pages, 12 figure
g_phi-pion-gamma coupling constant in light cone QCD sum rules
The coupling constant of g_phi-pion-gamma decay is calculated using light
cone QCD sum rules. A comparison of our result with the ones existing in the
literature is presented.Comment: 9 pages, 2 figure
Appeal No. 0750: Paul A. Grim v. Division of Mineral Resources Management
Chief\u27s Order 2005-2
Asymmetry Parameter of the by Analyzing the Transition Form Factors within QCD
Separating the mixture of the and states, the
transition form factors are calculated in
the three-point QCD sum rules approach. The longitudinal, transverse and total
decay widths as well as the asymmetry parameter, characterizing the
polarization of the axial and the branching ratio for these
decays are evaluated.Comment: 25 pages, 3 figures, 3 table
Strategy to find the two states from lattice QCD simulations
Theoretical studies within the chiral unitary approach, and recent
experiments, have provided evidence of the existence of two isoscalar states in
the region of the . In this paper we use the same chiral
approach to generate energy levels in a finite box. In a second step, assuming
that these energies correspond to lattice QCD results, we devise the best
strategy of analysis to obtain the two states in the infinite volume case, with
sufficient precision to distinguish them. We find out that using energy levels
obtained with asymmetric boxes and/or with a moving frame, with reasonable
errors in the energies, one has a successful scheme to get the two
poles.Comment: Published version (more discussions added based on referee's
suggestions, giving rise to a new section: IV
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