120570379
Direct photon production and the gluon EMC effect
Abstract Nuclear effects are studied in direct production of photons. It is seen that the analogue of the EMC ratio for gluons can be extracted from the cross sections obtained with proton beams incident on nuclei. The result is stable under higher order QCD corrections, and hence can be used to distinguish between models of the EMC effect. This process thus forms a versatile tool for the measurement of the gluon EMC ratio.
123004962
Flavour degrees of freedom and the transition temperature in QCD
We study the finite temperature transition in QCD with four flavours of dynamical quarks. Our simulation is performed on an 8×16 3 lattice for quarks of mass ma=0.01. At the coupling β c =5.15, we find long-lived metastable states, as well as an abrupt change in the entropy density, suggesting a first order phase transition. Using presently available results from corresponding calculations of the hadron masses and the chiral condensate, this gives us a transition temperature T c ≅100 MeV, which is a factor two lower than the transition temperature found in quenched QCD.
17443615
Lattice QCD for RHIC
I briefly introduce the methods by which lattice QCD predictions for RHIC are obtained. Next I deal with lattice determinations of strangeness production and event-to-event fluctuations of conserved quantities. I also present a new diagrammatic method for computing derivatives with respect to chemical potentials, and conclude with discussions of some tests of thermal perturbation theory which follow.
121387686
Hybrid Monte Carlo simulations of a two-dimensional gauge theory
Through a study of the dynamics of the two-dimensional U(1) pure gauge theory we find exponential slowing down in barrier penetration problems. We verify that the dynamical critical exponent in HMC can be tuned exactly to 1, and that normal and gauge fixed updates have equal cost.
122166973
The phase diagram of QCD: methods and logic of the comparison of experiments and theory
Abstract A small review of the phase diagram of QCD is presented. This is followed by a discussion of the conditions under which experimental data on the fluctuations of conserved quantities in heavy-ion collisions can be treated in the grand canonical ensemble. A robust method for detecting the presence of a nearby critical point in experiments is given. There is a short discussion of the need for non-Gaussian error analysis.
119431013
A precise determination of T_c in QCD from scaling
Existing lattice data on the QCD phase transition are analyzed in renormalized perturbation theory. In quenched QCD it is found that T_c scales for lattices with only 3 time slices, and that T_c/Lambda_msbar=1.15 \pm 0.05. A preliminary estimate in QCD with two flavours of dynamical quarks shows that this ratio depends on the quark mass. For realistic quark masses we estimate T_c/Lambda_msbar=0.49 \pm 0.02. We also investigate the equation of state in quenched QCD at 1-loop order in renormalised perturbation theory.
121860723
Possibility of structure in projectile fragmentation in high energy heavy ion reactions
Abstract We show that a quantum mechanical analogue of the Goldhaber model predicts a structure in the momentum distribution of α's fragmenting from the projectile 6 Li. This structure should be measurable.
122218899
A new macroscopic-microscopic description of the double-humped fission barriers
The new mass relation based on the generalised Hugenholtz-Van Hove theorem has been used to obtain a relation for the fission barriers of three nuclei. This relation has been found satisfactory to describe the data. Further a general expression has been given describing satisfactorily the inner barrier height, the second minimum and the second barrier height for all actinides with an rms deviation of 0.32, 0.32 and 0.33 MeV respectively. The estimated shell energies agree reasonably well with those of Brack et al. In addition the barriers for thorium isotopes have been described well.
121995970
A check on the geometrical assumptions in models of relativistic heavy ion collisions
Abstract The results of a recent experiment can be used to test clearly the geometrical assumptions of a variety of models for heavy ion collisions. Frequently used models are seen to fail quantitatively; the data show the need for incorporating nuclear transparency; both multiple and clean knockout collisions are needed.
14302099
Right-chiral sneutrinos and long-lived staus: Event characteristics at the CERN Large Hadron Collider
We investigate the signals of a supersymmetric scenario where the lighter tau-sneutrino is the lightest supersymmetric particle, while the lighter stau-state is the next lightest. We confirm that such a scenario can be motivated within the framework of minimal supergravity, with just the addition of a right-chiral neutrino superfield. Such a spectrum leads to rather unusual signals of supersymmetry, showing stable tracks of the stau in the muon chambers. We have studied two types of signals, namely (a) two or more hard jets and two stau tracks, and (b) hard jets with two muons and two stau tracks. We demonstrate that the stau tracks can be distinguished from the muonic ones through proper kinematic cuts which also enable one to remove all standard model backgrounds.
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.