2,554 research outputs found
Radiative transition of negative to positive parity nucleon
We investigate the transition in the
framework of light cone QCD sum rules. In particular, using the most general
form of the interpolating current for the nucleon as well as the distribution
amplitudes of the photon, we calculate two transition form factors responsible
for this channel and use them to evaluate the decay width and branching ratio
of the transition under consideration. The result obtained for the branching
fraction is in a good consistency with the experimental data.Comment: A typo has been correcte
Thermal behavior of the mass and residue of hyperons
We investigate the mass and residue of the , and
hyperons at finite temperature in the framework of thermal QCD sum rules. In
our calculation, we take into account the additional operators coming up at
finite temperature. We find the temperature-dependent continuum threshold for
each hyperon using the obtained sum rules for their mass and residue. The
numerical results demonstrate that the mass and residue of the particles under
consideration remain stable up to a certain temperature, after which they
decrease by increasing the temperature.Comment: 25Pages, 6 Figures and 2 Table
Semileptonic transitions in QCD
The form factors relevant to
decays are calculated in the framework of the three point QCD sum
rules approach. The heavy quark effective theory prediction of the form factors
are obtained. The total decay width and branching ratio for these decays are
also evaluated using the dependencies of these form factors.Comment: 4 pages, 4 figures and 3 tables. To be published in the proceedings
of the 14th International QCD Conference (QCD 08), Montpellier, France, 7-12
July 200
Modifications on nucleon parameters at finite temperature
Taking into account the additional operators coming up at finite temperature,
we investigate the mass and residue of the nucleon in the framework of thermal
QCD sum rules. We observe that the mass and residue of the nucleon are
initially insusceptible to increase of temperature, however after a certain
temperature, they start to fall increasing the temperature.Comment: 12 Pages, 4 Figures and 1 Tabl
Decuplet baryons in a hot medium
The thermal properties of the light decuplet baryons are investigated in the
framework of the thermal QCD sum rules. In particular, the behavior of the mass
and residue of the , , and baryons with
respect to temperature are analyzed taking into account the additional
operators coming up in the Wilson expansion at finite temperature. It is found
that the mass and residue of these particles remain overall unaffected up to
but, beyond this point, they start to diminish, considerably.Comment: 12 Pages, 4 Figures and 3 Table
Properties of nucleon in nuclear matter: once more
We calculate the mass and residue of the nucleon in nuclear matter in the
framework of QCD sum rules using the nucleon's interpolating current with an
arbitrary mixing parameter. We evaluate the effects of the nuclear medium on
these quantities and compare the obtained results with the existing theoretical
predictions. The results are also compared with those obtained in vacuum to
find the shifts in the quantities under consideration. Our calculations show
that these shifts in the mass and residue are about and ,
respectively.Comment: 18 Pages, 2 Tables and 7 Figures, To be appear in EPJ
QCD nature of dark energy at finite temperature: cosmological implications
The Veneziano ghost field has been proposed as an alternative source of dark
energy whose energy density is consistent with the cosmological observations.
In this model, the energy density of QCD ghost field is expressed in terms of
QCD degrees of freedom at zero temperature. We extend this model to finite
temperature to search the model predictions from late time to early universe.
We depict the variations of QCD parameters entering the calculations, dark
energy density, equation of state, Hubble and deceleration parameters on
temperature from zero to a critical temperature. We compare our results with
the observations and theoretical predictions existing at different eras. It is
found that this model safely defines the universe from quark condensation up to
now and its predictions are not in tension with those of the standard
cosmology. The EoS parameter of dark energy is dynamical and evolves from
in the presence of radiation to at late time. The finite
temperature ghost dark energy predictions on the Hubble parameter well fit to
those of CDM and observations at late time.Comment: 10 Pages and 6 Figures. Some references were rearrange
The masses and residues of doubly heavy spin--3/2 baryons
The masses and residues of the spin--3/2 doubly heavy baryons are calculated
within the QCD sum rules method. A comparison of our predictions with those
existing in the literature is also made.Comment: 11 Pages and 4 Table
- …