Production In Relativistic Ion Collisions Research Articles

Relativistic ion collisions as the source of hypernuclei

We shortly review the theory of hypernuclei production in relativistic ion collisions, that is adequate to future experiments at BM@N, NICA, and FAIR. Within a hybrid approach we use transport, coalescence and statistical models to describe the whole process. We demonstrate that the origin of hypernuclei can be explained by typical baryon interactions, that is similar to the production of conventional nuclei. In particular, heavy hypernuclei are coming mostly from projectile and target residues, whereas light hypernuclei can be produced at all rapidities. The yields of hypernuclei increase considerably above the energy threshold for $ \Lambda$ hyperon production, and there is a tendency to saturation of yields of hypernuclei with increasing the beam energy up to few TeV. There are unique opportunities in relativistic ion collisions which are difficult to realize in traditional hypernuclear experiments: The produced hypernuclei have a broad distribution in masses and isospin. They can even reach beyond the neutron and proton drip-lines and that opens a chance to investigate properties of exotic hypernuclei. One finds also the abundant production of multi-strange nuclei, of bound and unbound hypernuclear states with new decay modes. In addition, we can directly get an information on the hypermatter both at high and low temperatures.

Total Born cross section of e + e − -pair production in relativistic ion collisions from differential equations

We apply the differential equation method to the calculation of the total Born cross section of the process $Z_1Z_2\to Z_1Z_2e^+e^-$. We obtain explicit expression for the cross section exact in the relative velocity of the nuclei.

Lepton-pair production in relativistic ion collisions and its correspondence to the crossing process

Using the Sudakov technique, we sum the perturbation series for the process 3 → 3 and obtain the compact analytical expression for the amplitude of this process, which takes into account all possible Coulomb interactions between colliding particles. Comparing it to the amplitude of the lepton-pair production in heavy-ion collisions, i.e., in the process 2 → 4, we show that the amplitudes obtained in the high-energy limit lose the crossing-symmetry property (which holds only on the Born level).

Lepton pair production in relativistic ion collisions to all orders in Zα with logarithmic accuracy

The problem of summation of the perturbation series for the process of lepton pair production in relativistic ion collisions is investigated. We show that the amplitude of this process can be obtained in the compact analytical form, if one confines to the terms growing as powers of logarithmic energy in the cross section, the approximation of which is completely justified for such colliders as RHIC and LHC. Using this result we calculate the Coulomb corrections to the cross section of the process under consideration.

Multiple lepton pair production in relativistic ion collisions

We apply the Sudakov technique to description of the multiple production of lepton pairs in peripheral collisions of ultrarelativistic heavy ions. For heavy ions with Z 1 Z 2 α⩾1 one needs a careful treatment of the multiple Coulomb exchange between colliding ions and screening effects, whereas interaction of real or virtual lepton pairs with colliding ions can be neglected if one considers the nuclei which charge numbers satisfy the condition Z 1 α∼ Z 2 α⪡1. We demonstrate that while the inclusive spectra are modified by multiple Coulomb exchange between the colliding ions, the Coulomb corrections to the momentum integrated multiplicity distributions do vanish. After transformation to the impact parameter representation the probability of n lepton pair production is shown to obey the Poisson distribution. The relevant cross section is obtained.

Kaon production in relativistic ion collisions at 3.65 GeV/nucleon

Kaon production in relativistic ion collisions at 3.65 GeV/nucleon

Strangeness production in relativistic ion collisions — Theoretical review

The present situation of strangeness production in relativistic ion collisions is reviewed. The K/ π ratios, as measured at BNL, are compatible with the formation of a chemically equilibrated hadronic gas, the freeze-out temperature being 105 MeV and the freeze-out baryon density 0.05/fm 3. Recently measured hyperon ratios at CERN and the φ enhancement are also reviewed. The possibility of Bose-Einstein condensation for kaons is discussed.

Difficulties of the thermodynamical model approach to pion production in relativistic ion collisions

Difficulties of the thermodynamical model approach to pion production in relativistic ion collisions