118515325
Lattice QCD predictions for shapes of event distributions along the freezeout curve in heavy-ion collisions
We present lattice QCD results along the freezeout curve of heavy-ion collisions. The variance, skew and kurtosis of the event distribution of baryon number are studied through Pade resummations. We predict smooth behaviour of three ratios of these quantities at current RHIC and future LHC energies. Deviations from this at lower energies signal the presence of a nearby critical point.
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.
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.
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.
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.
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.
123088134
Proton optical model potential at sub-Coulomb energies for medium weight nuclei
The ($p$,$n$) reaction excitation functions for eleven nuclei from $A=45 \mathrm{to} 80$ measured at proton energies below \ensuremath{\sim}5 MeV have been analyzed utilizing the optical model. The real potential parameters used in the present work have been obtained by suitably combining the proton optical model parameters determined between 3 and 60 MeV. Large energy dependence of the real potential at energies below 5 MeV has been observed. The imaginary potential depths determined in the present analysis exhibit an anomalous behavior when plotted as a function of mass number $A$. By utilizing the low and intermediate energy proton data, an attempt has been made to obtain a "global" set of optical parameters in the proton energy range between 4 and 180 MeV, for medium weight nuclei.
54964643
Studies on Cosmic Ray Sidereal Anisotropy with the Multidirectional Muon Telescope at Ooty
We have developed a multidirectional telescope capable of recording individual muons with angular accuracy of about 5 degrees. This muon telescope consists of ∼ 3000 proportional counters with total area of ∼ 420 m with threshold energy > 1 GeV. The telescope is a component of the GRAPES-3 experiment at Ooty in southern India (N 11.4, E 76.7 and 2200m altitude). The very large muon counting rate ∼ 1.8×108 per hour, achieved due to the very large area of the telescope, gives us great advantage for cosmic ray modulation studies. The analysis of data with such high statistics enables us to have a sensitive measurement of sidereal variation within a single year of observation. Further, since our telescope is located near the Equator, we are able to observe both the Northern and the Southern hemispheres simultaneously. We present here the results on the sidereal variation obtained with this multidirectional muon telescope for the observational period, 2000–2001. We report here on Tail-in and Loss-corn anisotropies through detailed analysis. We also discuss other possible explanations for the present observations.
122335370
Transverse energy distributions in participant number model for ultra-relativistic heavy-ion collisions
The transverse energy distribution in ultra-relativistic heavy-ion collisions has been obtained as a convolution over the number of projectile and target participants. The latter is computed using the geometrical overlap model as a function of impact parameter. The data from 10 A GeV to 200 A GeV heavy ion beams on various targets in different pseudo-rapidity domains have been successfully described.
118955676
Phase transition in a statistical model for nuclear multifragmentation
We use a simplified model which is based on the same physics as inherent in most statistical models for nuclear multifragmentation. The simplified model allows exact calculations for thermodynamic properties of systems of large number of particles. This enables us to study a phase transition in the model. A first order phase transition can be tracked down. There are significant differences between this phase transition and some other well-known cases. {copyright} {ital 1998} {ital The American Physical Society}
93793271
Radial Flow has little effect on clusterization at intermediate energies
The lattice gas model was extended to incorporate the effect of radial flow. Contrary to popular belief, radial flow has little effect on the clusterization process in intermediate energy heavy-ion collisions except adding an ordered motion to the particles in the fragmentation source. We compared the results from the lattice gas model with and without radial flow to experimental data. We found that charge yields from central collisions are not significantly affected by inclusion of any reasonable radial flow.