119030036
Grand canonical model predictions for nuclear fragmentation
The grand canonical ensemble has been used to make predictions for composite yields using simple models for nuclear fragmentation. While this gives correct model prediction for high energy collisions, it can give very inaccurate results at intermediate energy.
119186084
Bimodality and Coulomb effects with a canonical thermodynamic model
Abstract The effect of the Coulomb interaction on the phase diagram of finite nuclei is studied within the Canonical Thermodynamic Model. If Coulomb effects are artificially switched off, this model shows a phenomenology consistent with the liquid–gas phase transition. The inclusion of Coulomb does not significantly affect the phase diagram but it drastically modifies the nature and order parameter of the transition. A clear understanding of the phenomenon can be achieved looking at the distribution of the largest fragment produced in each fragmentation event. Possible connections with experimental observations are outlined.
2820708
Transverse momenta, nuclear equation of state, and momentum-dependent interactions in heavy-ion collisions.
We investigate the generation of transverse momentum in high-energy heavy-ion collisions and its relation to the nuclear equation of state. We find that streamer chamber data can be fitted by Boltzmann-Uehling-Uhlenbeck calculations with a momentum-dependent potential that closely models realistic nuclear matter interactions and yields an equation of state with {ital K}=215 MeV.
121836312
Excluded volume in nuclear fragmentation
14927510
A Transport Model for Nuclear Reactions Induced by Radioactive Beams
Major ingredients of an isospin and momentum dependent transport model for nuclear reactions induced by radioactive beams are outlined. Within the IBUU04 version of this model we study several experimental probes of the equation of state of neutron‐rich matter, especially the density dependence of the nuclear symmetry energy. Comparing with the recent experimental data from NSCL/MSU on isospin diffusion, we found a nuclear symmetry energy of Esym(ρ) ≈ 31.6(ρ/ρ0)1.05 at subnormal densities. Predictions on several observables sensitive to the density dependence of the symmetry energy at supranormal densities accessible at GSI and the planned Rare Isotope Accelerator (RIA) are also made.
16308546
First Order Phase Transition in Intermediate-Energy Heavy Ion Collisions
We model the disassembly of an excited nuclear system formed as a result of a heavy ion collision. We find that, as the beam energy in central collisions in varied, the dissociating system crosses a liquid-gas coexistence curve, resulting in a first-order phase transition. Accessible experimental signatures are identified: a peak in specific heat, a power-law yield for composites, and a maximum in the second moment of the yield distribution.
121323084
Microscopic nucleon optical model potential at low energies
Nuclear optical model potentials at low energies have been computed utilizing the two (Micro I and Micro II) versions of the microscopic optical model of Jeukenne et al. A comparison has been made of the experimental nucleon-nucleus interaction data for E<10 MeV with the theoretical predictions obtained using the microscopic optical model.
121044914
RENORMALIZATION OF QUANTUM CHROMODYNAMICS
Renormalization of quantum chromodynamics is carried out by means of a momentum-space subtraction scheme, which is computationally simple, provides a well-defined procedure for the determination of renormalization constants, and is equally applicable to light and heavy quarks. We also obtain the renormalization-group parameters, verify the decoupling theorem for heavy quarks, and compute the effective coupling constant and effective quark masses.
54647998
Lattice QCD with chemical potential: Evading the fermion-sign problem
Since the turn of the millennium there has been tremendous progress in understanding QCD at finite chemical potential, μ. Apart from qualitative results obtained using models, and exact results at very large μ obtained in weak coupling theory, there has been tremendous progress in getting exact and quantitative results from lattice simulations. I summarize the status of lattice QCD at finite chemical potential —locating the critical end-point in the QCD phase diagram, predicting event-to-event fluctuation rates of conserved quantities, and finding the rate of strangeness production.
122387961
Electromagnetic interaction of higher-spin fields
The electromagnetic interaction of fields of spins 3/2 and 2 is investigated with the use of the ghost-field formalism. It is thus shown that the canonical formalism for interacting higher-spin fields can be developed in a straightforward manner, which avoids the complexities and controversies of the conventional formalism. Our detailed treatment of the Lorentz invariance of the scattering operator and the gauge invariance of the photon self-energy resulting from spin-3/2 fermion and spin-2 boson loops shows that the quantum theory of interacting spin-3/2 and spin-2 fields does not present any unusual difficulty. However, the electromagnetic interaction of both of these fields is nonrenormalizable, which is expected from power-counting arguments as well as supported by explicit calculations.
119974560
Eikonal model description of forward energy distribution in oxygen-induced reactions at 60 A GeV and 200 A GeV
The forward energy flow cross section is described in terms of the projectile-nucleon abrasion probability which is calculated in the impact parameter representation within the framework of the Glauber multiple scattering formalism. Realistic nuclear densities and the nucleon-nucleon inelastic cross section have been used in the calculation. The recent WA80 data are in reasonable agreement with the calculation. A simple relationship has been obtained between the abrased nucleons from the target and projectile and the zero degree energy.