8,270 research outputs found
LRS Bianchi type-I cosmological model with constant deceleration parameter in gravity
A spatially homogeneous anisotropic LRS Bianchi type-I cosmological model is
studied in gravity with a special form of Hubble's parameter, which
leads to constant deceleration parameter. The parameters involved in the
considered form of Hubble parameter can be tuned to match, our models with the
CDM model. With the present observed value of the deceleration
parameter, we have discussed physical and kinematical properties of a specific
model. Moreover, we have discussed the cosmological distances for our model.Comment: Published versio
Ba Quadrupole Polarizabilities: Theory versus Experiment
Three different measurements have been reported for the ground state
quadrupole polarizability in the singly ionized barium (Ba) which disagree
with each other. Our calculation of this quantity using the relativistic
coupled-cluster method disagrees with two of the experimental values and is
within the error bars of the other. We discuss the issues related to the
accuracy of our calculations and emphasize the need for further experiments to
measure the quadrupole polarizability for this state and/or the 5D states.Comment: 6 pages, 3 table
Effective-energy budget in multiparticle production in nuclear collisions
The dependencies of charged particle pseudorapidity density and transverse
energy pseudorapidity density at midrapidity on the collision energy and on the
number of nucleon participants, or centrality, measured in nucleus-nucleus
collisions are studied in the energy range spanning a few GeV to a few TeV per
nucleon. The model in which the multiparticle production is driven by the
dissipating effective energy of participants is introduced. The model is based
on the earlier proposed approach, combining the constituent quark picture
together with Landau relativistic hydrodynamics shown to interrelate the
measurements from different types of collisions. Within this model, the
dependence on the number of participants in heavy-ion collisions are found to
be well described in terms of the effective energy defined as a
centrality-dependent fraction of the collision energy. For both variables under
study, the effective energy approach reveals a similarity in the energy
dependence obtained for the most central collisions and centrality data in the
entire available energy range. Predictions are made for the investigated
dependencies for the forthcoming higher energy measurements in heavy-ion
collisions at the LHC.Comment: Regular article, Replaced with published versio
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