118357251
Fractal structure of near-threshold quarkonium production off cold nuclear matter
We investigate near-threshold production of quarkonium resonances in cold nuclear matter through a scaling theory with two exponents which are fixed by existing data on near-threshold J/psi production in proton-nucleus collisions. Interestingly, it seems possible to extend one of the multifractal dimensions to the production of other mesons in cold nuclear matter. The scaling theory can be tested and refined in experiments at the upcoming high-intensity FAIR accelerator complex in GSI.
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.
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.
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.
119119867
Phase diagram for asymmetric nuclear matter in the multifragmentation model
We assume that, in equilibrium, nuclear matter at reduced density and moderate finite temperature breaks up into many fragments. Strong support for this assumption is provided by data accumulated from intermediate-energy heavy ion collisions. The breakup of hot and expanded nuclear matter according to the rules of equilibrium statistical mechanics is the multifragmentation model, which gives a first-order phase transition. This is studied in detail here. Phase-equilibrium lines for different degrees of asymmetry are computed.
118170067
Canonical brackets from continuous symmetries: Abelian 2-form gauge theory
We derive the canonical (anti-)commutation relations amongst the creation and annihilation operators of the various basic fields, present in the four (3 + 1)-dimensional (4D) free Abelian 2-from gauge theory, with the help of continuous symmetry transformations within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism. We show that all the six continuous symmetries of the theory lead to the exactly the same non-vanishing (anti-)commutator amongst the creation and annihilation operators of the normal mode expansion of the basic fields of the theory.
119711961
Aspects of deuteron production in relativistic heavy ion collisions
One criticism of the thermodynamic model for deuteron production has been that it may not be possible for deuterons to exist inside the fireball. We give arguments why deuterons can exist inside the fireball, although they cannot exist in cold nuclear matter at normal density. We redefine the Berkeley coalescence model and show that with this redefinition, the coalescence model is rather close to the thermodynamic prescription. We show that this redefined coalescence model is equivalent to the quantum mechanical sudden approximation model considered by Kapusta. We construct the grand canonical partition function for interacting fermions up to the second virial coefficient and show that the redefined coalescence model and the simple thermodynamic model are two limits of a more complete theory.
118567719
A Study of Nuclear Composition of Primary Cosmic Rays above 100 TeV
The GRAPES-3 air shower array is located at Ooty (800g/cm) in southern India and consists of 256 scintillation detectors (1m each) and 16 muon detectors (35m each). In order to study the nuclear composition of primary cosmic rays around the knee energy, we investigate the relation between muon multiplicity and shower size using observations from this experiment during the period, 2000– 2001 with ∼ 10 showers having Ne > 10. These results are compared with Monte Carlo simulations (CORSIKA v6.02 with QGSJET model) to obtain the variation of the average mass number with primary energy. We have carried out detailed simulations for five types of primary nucleus (Proton, He, N, Al and Fe) for comparison with observations. We present here the details of the results.
5816018
Variational principle model for the nuclear caloric curve
Following the lead of a recent work, I perform a variational principle model calculation for the nuclear caloric curve. A Skyrme-type interaction with and without momentum dependence is used. The calculation is done for a large nucleus, i.e., in the nuclear matter limit. Thus I address the issue of volume fragmentation only. Nonetheless, the results are similar to the previous, largely phenomenological calculation for a finite nucleus. I find that the onset of fragmentation can be sudden as a function of temperature or excitation energy.