456 research outputs found
Model for Glass Transition in a Binary fluid from a Mode Coupling approach
We consider the Mode Coupling Theory (MCT) of Glass transition for a Binary
fluid. The Equations of Nonlinear Fluctuating Hydrodynamics are obtained with a
proper choice of the slow variables corresponding to the conservation laws. The
resulting model equations are solved in the long time limit to locate the
dynamic transition. The transition point from our model is considerably higher
than predicted in existing MCT models for binary systems. This is in agreement
with what is seen in Computer Simulation of binary fluids. fluids.Comment: 9 Pages, 3 Figure
Metal-insulator transition in disordered 2DEG including temperature effects
We calculate self-consistently the mutual dependence of electron correlations
and electron-defect scattering for a two dimensional electron gas at finite
temperature. We employ an STLS approach to calculate the electron correlations
while the electron scattering rate off Coulombic impurities and surface
roughness is calculated using self-consistent current-relaxation theory. The
methods are combined and self-consistently solved. We discuss a metal-insulator
transition for a range of disorder levels and electron densities. Our results
are in good agreement with recent experimental observations.Comment: 4 pages, RevTeX + epsf, 5 figure
Effect of Composition Changes on the Structural Relaxation of a Binary Mixture
Within the mode-coupling theory for idealized glass transitions, we study the
evolution of structural relaxation in binary mixtures of hard spheres with size
ratios of the two components varying between 0.5 and 1.0. We find two
scenarios for the glassy dynamics. For small size disparity, the mixing yields
a slight extension of the glass regime. For larger size disparity, a
plasticization effect is obtained, leading to a stabilization of the liquid due
to mixing. For all , a decrease of the elastic moduli at the transition
due to mixing is predicted. A stiffening of the glass structure is found as is
reflected by the increase of the Debye-Waller factors at the transition points.
The critical amplitudes for density fluctuations at small and intermediate wave
vectors decrease upon mixing, and thus the universal formulas for the
relaxation near the plateau values describe a slowing down of the dynamics upon
mixing for the first step of the two-step relaxation scenario. The results
explain the qualitative features of mixing effects reported by Williams and van
Megen [Phys. Rev. E \textbf{64}, 041502 (2001)] for dynamical light-scattering
measurements on binary mixtures of hard-sphere-like colloids with size ratio
How does Inflation Depend Upon the Nature of Fluids Filling Up the Universe in Brane World Scenario
By constructing different parameters which are able to give us the
information about our universe during inflation,(specially at the start and the
end of the inflationary universe) a brief idea of brane world inflation is
given in this work. What will be the size of the universe at the end of
inflation,i.e.,how many times will it grow than today's size is been speculated
and analysed thereafter. Different kinds of fluids are taken to be the matter
inside the brane. It is observed that in the case of highly positive pressure
grower gas like polytropic,the size of the universe at the end of inflation is
comparitively smaller. Whereas for negative pressure creators (like chaplygin
gas) this size is much bigger. Except thse two cases, inflation has been
studied for barotropic fluid and linear redshift parametrization too. For them the size of the universe after
inflation is much more high. We also have seen that this size does not depend
upon the potential energy at the end of the inflation. On the contrary, there
is a high impact of the initial potential energy upon the size of inflation.Comment: 20 page
Dynamics of Modified Chaplygin Gas in Brane World Scenario: Phase Plane Analysis
In this work we investigate the background dynamics when dark energy is
coupled to dark matter with a suitable interaction in the universe described by
brane cosmology. Here DGP and the RSII brane models have been considered
separately. Dark energy in the form of modified Chaplygin gas is considered. A
suitable interaction between dark energy and dark matter is considered in order
to at least alleviate (if not solve) the cosmic coincidence problem. The
dynamical system of equations is solved numerically and a stable scaling
solution is obtained. A significant attempt towards the solution of the cosmic
coincidence problem is taken. The statefinder parameters are also calculated to
classify the dark energy models. Graphs and phase diagrams are drawn to study
the variations of these parameters. It is also seen that the background
dynamics of modified Chaplygin gas is completely consistent with the notion of
an accelerated expansion in the late universe. Finally, it has been shown that
the universe in both the models follows the power law form of expansion around
the critical point, which is consistent with the known results.Comment: 14 pages, 14 figure
ϒ production in p–Pb collisions at √sNN=8.16 TeV
ϒ production in p–Pb interactions is studied at the centre-of-mass energy per nucleon–nucleon collision √sNN = 8.16 TeV with the ALICE detector at the CERN LHC. The measurement is performed reconstructing bottomonium resonances via their dimuon decay channel, in the centre-of-mass rapidity intervals 2.03 < ycms < 3.53 and −4.46 < ycms < −2.96, down to zero transverse momentum. In this work, results on the ϒ(1S) production cross section as a function of rapidity and transverse momentum are presented. The corresponding nuclear modification factor shows a suppression of the ϒ(1S) yields with respect to pp collisions, both at forward and backward rapidity. This suppression is stronger in the low transverse momentum region and shows no significant dependence on the centrality of the interactions. Furthermore, the ϒ(2S) nuclear modification factor is evaluated, suggesting a suppression similar to that of the ϒ(1S). A first measurement of the ϒ(3S) has also been performed. Finally, results are compared with previous ALICE measurements in p–Pb collisions at √sNN = 5.02 TeV and with theoretical calculations.publishedVersio
(Anti-)deuteron production in pp collisions at 1as=13TeV
The study of (anti-)deuteron production in pp collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. In this paper the production of (anti-)deuterons is studied as a function of the charged particle multiplicity in inelastic pp collisions at s=13 TeV using the ALICE experiment. Thanks to the large number of accumulated minimum bias events, it has been possible to measure (anti-)deuteron production in pp collisions up to the same charged particle multiplicity (d Nch/ d \u3b7 3c 26) as measured in p\u2013Pb collisions at similar centre-of-mass energies. Within the uncertainties, the deuteron yield in pp collisions resembles the one in p\u2013Pb interactions, suggesting a common formation mechanism behind the production of light nuclei in hadronic interactions. In this context the measurements are compared with the expectations of coalescence and statistical hadronisation models (SHM)
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