23 research outputs found
Multicomponent Van der Waals model of a nuclear fireball in the freeze-out stage
A two-component van der Waals gas model is proposed to describe the hadronic
stages of the evolution of a nuclear fireball in the cooling stage. At the
first stage of hadronization, when mesons dominate, a two-component meson model
( and -mesons) with an effective two-particle interaction
potential of a rectangular well is proposed. At the late-stage hadronization,
when almost all mesons have decayed, a two-component nucleon model of protons
and neutrons is proposed with the corresponding effective rectangular nucleon
potential. The saddle point method has been applied for analytical calculations
of the partition function. This made it possible to uniformly obtain analytical
expressions for both the pressure and density, taking into account the finite
dimensions of the system, and the analytical expressions for chemical
potentials. It is assumed that the proposed models and derived formulas can be
used to analyze experimental data connected to the quantitative characteristics
of the particle yields of different types in the final state from the hadronic
stages of the evolution of a nuclear fireball, as well as to determine the
critical parameters of the system in high-energy nucleus-nucleus collisions.Comment: 18 pages, 8 figures(29-th Annual Scientific Conference of Institute
for Nuclear Research, Kyiv, September 26-30, 2022
The elastic electron-deuteron scattering beyond one-photon exchange
We discuss the elastic ed scattering beyond Born approximation. It is shown
that the reaction amplitude contains six generalized form factors, but only
three linearly independent combinations of them (we call them generalized
charge, quadrupole and magnetic form factors) contribute to the reaction cross
section in the second order perturbation theory. We examine two-photon exchange
and find that it includes two types of diagrams, when two virtual photons
interact with the same nucleon and when the photons interact with different
nucleons. Estimations based on nonrelativistic calculations with the deuteron
wave function for realistic NN potential show that the main contribution to the
generalized charge, quadrupole and magnetic form factors comes from diagrams of
the first type.Comment: v2, published version in PR
Van der Waals Excluded Volume Model of Multicomponent Hadron Gas
A generalization of the Van der Waals excluded volume procedure for the
multicomponent hadron gas is proposed. The derivation is based on the grand
canonical partition function for the system of particles of several species
interacting by hard core potentials. The obtained formulae for thermodynamical
quantities are consistent with underlying principles of statistical mechanics
as well as with thermodynamical identities. The model can be applied to the
analysis of experimental data for particle number ratios in relativistic
nucleus-nucleus collisions.Comment: 8 page