122137392
A case study in intermittency: The Thermodynamic Model for intermediate energy heavy ion collisions
Abstract The Thermodynamic Model for heavy ion collisions explains, at least semi-quantitatively, many, though not all, features of the experimental data at Bevalac energies. We use this model as a case study for intermittency. A composite with n nucleons and total momentum P will be registered at the detector as n nucleons each with momentum P / n . We find that in this model the scaled factorial moments grow indefinitely with M where M is the number of divisions in the p z window. In so far as composites are droplets of various sizes (free nucleons constitute a gas), intermittency is seen to be linked to the existence of droplets. The role of resonances is examined by including excited “deuterons” whose mass determines the width of the momentum distribution of the decay nucleons. For nucleons and resonances only, the scaled factorial moments saturate with M when the bin size becomes smaller than the width. These results do not depend upon the size of the colliding systems thus the model cannot explain why, for example, e + e − shows stronger intermittency than the currently available heavy ion data.
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.
15293327
Liquid-Gas Phase Transition in Nuclear Multifragmentation
Heavy-ion collisions allow one to pump energy into a nuclear system. In central collisions of equal size nuclei one can also create a significant amount of compression using high energy nuclear beams. The possibility of studying nuclei far from normal conditions raises the question: can we study phase transitions in nuclei similar, for instance, to the way, one can study phase transition in water? This is the subject of the present article.
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
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.
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.
122594393
Minijets and associated production of photons and muons in high energy heavy ion collisions
Due to the large hadronic multiplicities involved in heavy ion collisions at LHC energies, production of photons and muons inside jets cannot be distinguished from production in isolation. Associated production rates for photons and muons in minijets are estimated. It is found that the muon cross section per uranium-uranium collision could be substantial.
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.
122167852
MULTIPLE PHOTON PRODUCTION IN QUANTUM ELECTRODYNAMICS
Multiple production of photons in high-energy processes in quantum electrodynamics is investigated, and the electron-positron annihilation is specially discussed in detail. It is found that at very high energies in cosmic rays, multiple production of up to four or five observable photons can easily take place. But, the probability, according to quantum electrodynamics, for the multiple production of a larger number of observable photons is quite small.
118739941
Novel symmetries in vector Schwinger model
We derive nilpotent and absolutely anticommuting (anti-)co-BRST symmetry transformations for the bosonized version of (1+1)-dimensional (2D) vector Schwinger model. These symmetry transformations turn out to be the analog of co-exterior derivative of differential geometry as the total gauge-fixing term remains invariant under it. The exterior derivative is realized in terms of the (anti-)BRST symmetry transformations of the theory whereas the bosonic symmetries find their analog in the Laplacian operator. The algebra obeyed by these symmetry transformations turns out to be exactly same as the algebra obeyed by the de Rham cohomological operators of differential geometry.