22,909 research outputs found
Vacuum structure and effective potential at finite temperature: a variational approach
We compute the effective potential for theory with a squeezed
coherent state type of construct for the ground state. The method essentially
consists in optimising the basis at zero and finite temperatures. The gap
equation becomes identical to resumming the infinite series of daisy and super
daisy graphs while the effective potential includes multiloop effects and
agrees with that obtained through composite operator formalism at finite
temperature.Comment: 15 pages, Revtex, No figures, to appear in Jou. of Phys.G(Nucl. and
Part. Phys.
Chiral Symmetry Breaking and Pion Wave Function
We consider here chiral symmetry breaking through nontrivial vacuum structure
with quark antiquark condensates. We then relate the condensate function to the
wave function of pion as a Goldstone mode. This simultaneously yields the pion
also as a quark antiquark bound state as a localised zero mode in vacuum. We
illustrate the above with Nambu Jona-Lasinio model to calculate different
pionic properties in terms of the vacuum structure for breaking of exact or
approximate chiral symmetry, as well as the condensate fluctuations giving rise
to mesons.Comment: latex, revtex, 16 page
D mesons and charmonium states in asymmetric nuclear matter at finite temperatures
We investigate the in-medium masses of and mesons in the
isospin-asymmetric nuclear matter at finite temperatures arising due to the
interactions with the nucleons, the scalar isoscalar meson , and the
scalar iso-vector meson within a SU(4) model. The in-medium masses of
and the excited charmonium states ( and ) are
also calculated in the hot isospin asymmetric nuclear matter in the present
investigation. These mass modifications arise due to the interaction of the
charmonium states with the gluon condensates of QCD, simulated by a scalar
dilaton field introduced to incorporate the broken scale invariance of QCD
within the effective chiral model. The change in the mass of in the
nuclear matter with the density is seen to be rather small, as has been shown
in the literature by using various approaches, whereas, the masses of the
excited states of charmonium ( and ) are seen to have
considerable drop at high densities. The present study of the in-medium masses
of () mesons as well as of the charmonium states will be of
relevance for the observables from the compressed baryonic matter, like the
production and collective flow of the () mesons, resulting from the
asymmetric heavy ion collision experiments planned at the future facility of
the FAIR, GSI. The mass modifications of and mesons as well as of
the charmonium states in hot nuclear medium can modify the decay of the
charmonium states () to pairs in the hot
dense hadronic matter. The small attractive potentials observed for the
mesons may lead to formation of the mesic nuclei.Comment: 61 pages, 19 figues, to be published in Phys. Rev.
Intake ground vortex characteristics
The development of ground vortices when an intake operates in close proximity to the ground has been studied computationally for several configurations including front and rear quarter approaching flows as well as tailwind arrangements. The investigations have been conducted at model scale using a generic intake geometry. Reynolds Averaged Navier–Stokes calculations have been used and an initial validation of the computational model has been carried out against experimental data. The computational method has subsequently been applied to configurations that are difficult to test experimentally by including tailwind and rear quarter flows. The results, along with those from a previous compatible study of headwind and pure cross-wind configurations, have been used to assess the ground vortex behaviour under a broad range of velocity ratios and approaching wind angles. The characteristics provide insights on the influence of the size and strength of ground vortices on the overall quality of the flow ingested by the intake
Anisotropic cosmological models with two fluids
In this paper, aniostropic dark energy cosmological models have been
constructed in a Bianchi-V space-time with the energy momentum tensor
consisting of two non-interacting fluids namely bulk viscous fluid and dark
energy fluid. Two different models are constructed based on the power law
cosmology and de Sitter universe. The constructed model also embedded with
different pressure gradients along different spatial directions. The variable
equation of state (EoS) parameter, skewness parameters for both the models are
obtained and analyzed. The physical properties of the models obtained with the
use of scale factors of power law and de Sitter law are also presented.Comment: 10 pages, 12 figure
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