arXiv subjects

D. Anchishkin

Publications and source records attributed to D. Anchishkin.

22 records · Page 2Linked to original sources

arXiv2005

Pion and Quark Annihilation Mechanisms of Dilepton Production in Relativistic Heavy-Ion Collisions

We revise the pion-pion and quark-quark annihilation mechanisms of dilepton production during relativistic heavy-ion collisions. We focus on the modifications caused by the specific features of intramedium pion states rather than by medium modification of the rho-meson spectral density. The main ingredient emerging in our approach is a form-factor of the multi-pion (multi-quark) system. Replacing the usual delta-function the form-factor plays the role of distribution which, in some sense, "connects" the 4-momenta of the annihilating and outgoing particles. The difference between the c.m.s. velocities attributed to annihilating and outgoing particles is a particular consequence of this replacement and results in the appearance of a new factor in the formula for the dilepton production rate. We obtained that the form-factor of the multi-pion (multi-quark) system causes broadening of the rate which is most pronounced for small invariant masses, in particular, we obtain a growth of the rate for the invariant masses below two masses of the annihilating particles.

hep-ph↗

arXiv2004

Annihilation Mechanism of Dilepton Emission from Finite Fireball

Medium-induced modifications of the pion and quark-antiquark annihilation mechanisms of dilepton production during relativistic heavy ion collisions are considered. Due to the dense hadron environment, the pions produced during a collision are effectively confined in a finite volume, in which they live for a finite time which is scaled as the lifetime of a fireball. Our results indicate that, due to the space-time finiteness of the pion system which generates the corresponding quantum randomization, the dilepton rates are finite in the invariant low-mass region M<2m_π. It is found that the spatial finiteness of quark wave functions and the finiteness of the lifetime of excited states result in the same effect for the quark-antiquark annihilation to dileptons. The breaking of the detailed energy-momentum conservation due to the broken translation invariance is discussed.

nucl-th↗

arXiv2002

Thermal Dilepton Radiation from Finite Fireball

We analyze the dilepton emission rates from the hot pion gas confined to a finite space-time volume. Two models of pion(+) pion(-) annihilation to dileptons are under consideration. The first model mimics an extreme influence of the dense hadron environment on the rho-meson mean free path and mean life time. The second model deals with the standard concept of vector meson dominance when the hadron medium is not accounted. Our results indicate that the dilepton rates are finite in the low invariant mass region M<2m_π. It is found that the rates experience an enhancement in the electron-positron production when invariant mass tends to the "real" threshold M=2m_e. The breaking of the detailled energy-momentum conservation in favour of the integral one due to broken translation invariance is discussed.

hep-ph↗

arXiv1997

Final state interactions in two-particle interferometry

We reconsider the influence of two-particle final state interactions (FSI) on two-particle Bose-Einstein interferometry. We concentrate in particular on the problem of particle emission at different times. Assuming chaoticity of the source, we derive a new general expression for the symmetrized two-particle cross section. We discuss the approximations needed to derive from the general result the Koonin-Pratt formula. Introducing a less stringent version of the so-called smoothness approximation we also derive a more accurate formula. It can be implemented into classical event generators and allows to calculate FSI corrected two-particle correlation functions via modified Bose-Einstein "weights".

nucl-th↗