35500264
Intermittency in quark-gluon-plasma phase transition.
Intermittency properties of the multiplicity fluctuations in high energy heavy ion collisions have been studied on the basis of Landau mean field approach. A universal scaling exponent for hadron phase is found which does not depend on whether the transition is of first or second order. It is further shown that the multiplicity distributions at different rapidity intervals carry more discriminating information about the nature of the phase transition.
2366114
Pattern recognition of particle tracks using principal component analysis and artificial neural network
Abstract A new method is suggested for pattern recognition of particle tracks based on a combined approach of both artificial neural network (ANN) and principal component analysis (PCA). It is seen that in high multiplicity environment, neither the PCA nor the ANN method is satisfactory when used separately as a track classifier. Best performance is achieved when the data are preprocessed using PCA technique, before it is fed to the backpropagated neural network.
119558719
Assembly, testing and production of bakelite RPCs for the end-cap region of the Compact Muon Solenoid experiment at CERN
Abstract The production of ten large area Resistive Plate Chambers (RPCs) for the end-cap region of CMS, under India-CMS-RPC Collaboration—“Action Plan (Phase-I)”, is in progress at the Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, in active collaboration with Delhi University and Panjab University. These detectors are being assembled with gas-gaps fabricated in KODEL-Korea, mechanics from China and the FEBs from Italy. After testing and validating the series for REi/2,3, these chambers would be sent to CMS at CERN. This paper reports various pre-assembly jobs, leak tests and leakage current measurements of the gas-gaps, mechanical assembly and progress of ten RPCs under production.
44941537
Entrance-channel dependence of fission-fragment anisotropies: A direct experimental signature of fission before equilibration.
Fission-fragment angular distributions in reactions of {sup 10}B, {sup 12}C, {sup 16}O+{sup 232}Th and {sup 237}Np, and {sup 19}F+{sup 237}Np have been measured. While the measured anisotropies in B- and C-induced fission are found to be in agreement with the predictions of the standard Halpern-Strutinsky theory, they are anomalously large in the case of O- and F-induced fission. Such a discontinuous behavior in angular anisotropy with respect to the entrance-channel mass-to-charge asymmetry provides an experimental verification of the predictions of the preequilibrium fission model proposed earlier to explain the anomalous fragment angular distributions.
15159040
Dissipative phenomena in a chemically nonequilibrated quark gluon plasma
The dissipative corrections to the hydrodynamic equations describing the evolution of energy-momentum tensor and parton densities are derived in a simple way using the scaling approximation for the expanding quark gluon plasma at finite baryon density. This procedure has been extended to study the process of chemical equilibration using a set of rate equations appropriate for a viscous quark gluon plasma. It is found that in the presence of dissipation, the temperature of the plasma evolves slower, whereas the quark and gluon fugacities evolve faster than their counterparts in the ideal case without viscosity.
120756008
Supercooling in viscous hydrodynamics for QCD phase transition
First order quark hadron phase transition is considered in scaling hydrodynamics including the Csernai-Kapusta model of nucleation of hadronic bubbles leading to supercooling. The effect of viscosity on the entropy production is studied in ideal as well as in viscous hydrodynamics with and without supercooling. It is found that the excess entropy produced due to supercooling depends weakly on viscosity.
18835111
Chern-Simons-type photon mass from fermion electric dipole moments at finite temperature in 3+1 dimensions.
We study the low-energy effective field theory of fermions with electric and magnetic dipole moments at finite temperature. We find that at one loop there is an interaction term of the Chern-Simons form ${\mathcal{L}}_{\mathcal{I}}={M}_{\ensuremath{\mu}}{A}_{\ensuremath{\nu}}{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{F}}^{\ensuremath{\mu}\ensuremath{\nu}}$. The four-vector ${M}_{\ensuremath{\mu}}\ensuremath{\simeq}{d}_{i}{\ensuremath{\mu}}_{i}{m}_{i}^{2}{\ensuremath{\partial}}_{\ensuremath{\mu}}(\mathrm{ln}T)$ is interpreted as a Chern-Simons-type mass of photons, which is determined by the electric (magnetic) dipole moments ${d}_{i}({\ensuremath{\mu}}_{i})$ of the fermions in the vacuum polarization loop diagram. The physical consequence of such a photon mass is that photons of opposite circular polarizations, propagating through a hot medium, have different group velocities. We estimate the time lag between the arrival times of the left and right circularly polarized light signals from pulsars. If the light propagates through a hot plasma (where the temperature in some regions is $T\ensuremath{\sim}100$ MeV) then the time lag between the two circularly polarized signals of frequency $\ensuremath{\omega}$ will be $\ensuremath{\Delta}t(\ensuremath{\omega})\ensuremath{\simeq}\frac{{10}^{\ensuremath{-}6}}{\ensuremath{\omega}}$. It may be possible to observe this effect in pulsar signals which propagate through nebulas at high temperatures.