118484055
Symmetry energy from fragment observables in the canonical thermodynamic model
Different formulas relating measurable fragment isotopic observables to the symmetry energy of excited nuclei were proposed and applied to the analysis of heavy ion collision data in the recent literature. In this article, we examine the quality of the different expressions in the framework of the McGill canonical thermodynamic model (CTM). We show that even in the idealized situation of canonical equilibrium and in the absence of secondary decay, these formulas do not give a precise reconstruction of the symmetry energy of the fragmenting source. However, both isotopic widths and isoscaling appear very well correlated to the physical symmetry energy.
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.
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.
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.
121836312
Excluded volume in nuclear fragmentation
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.
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.
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.
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.
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.
119399090
Obstructions to dimensional reduction in hot QCD
Abstract I describe results on screening masses in hot gauge theories. Wilsonian effective long distance theories called dimensionally reduced (DR) theories describe very well the longest screening length in pure gauge theories. In the presence of fermions, meson-like screening lengths dominate the long-distance physics for 3 T c /2 ≤ T T c , and thus obstruct perturbative DR. Extrapolation of our results indicates that a form of this obstruction may remain till temperatures of 10 T c or higher, and therefore affect the entire range of temperature expected to be reached even at the Large Hadron Collider.