Femtoscopic correlations of two identical particles with nonzero spin in the model of one-particle multipole sources
2019 August 19
2019 August 23
The process of emission of two identical particles with
nonzero spin $S$ and different helicities in relativistic heavy-ion collisions is theoretically
investigated within the model of one-particle multipole
sources. Taking into account the unitarity of the finite
rotation matrix and the symmetry relations for $d$--functions,
the general expression for the probability of emission of
two identical particles by two multipole sources with
angular momentum $J$, averaged over the angular momentum
projections and over the space-time dimensions of
the multiple particle generation region, has been obtained.
For the case of unpolarized particles, the additional
averaging over helicities is performed and the formula
for two-particle correlation function at sufficiently large
4-momentum difference $q$ is derived. For particles with nonzero mass, this formula is considerably simplified in the case when the angle $\beta$ between the particle momenta equals zero, and also in the case when $J = S$.
In addition, the special
cases of emission
of two unpolarized photons by dipole and quadrupole
sources, and emission of two "left" neutrinos
( "right" antineutrinos ) by sources with arbitrary $J$
have been also considered, and the respective
explicit expressions for the correlation function are obtained.