Possible effect of mixed phase and deconfinement upon spin correlations in the pairs generated in relativistic heavy-ion collisions

Abstract

Spin correlations for the ΛΛ and pairs, generated in relativistic heavy-ion collisions, and related angular correlations at the joint registration of space-parity nonconserving hadronic decays of two hyperons are theoretically analyzed. The correlation tensor components can be derived from the double angular distribution of products of two decays by the method of “moments”. The properties of the “trace” of the correlation tensor (a sum of three diagonal components), determining the angular correlations as well as the relative fractions of the triplet and singlet states of respective pairs, are discussed. In the present report, spin correlations for two identical (ΛΛ) and two non-identical particles are generally considered within the conventional model of one-particle sources, implying that correlations vanish at sufficiently large relative momenta. However, under these conditions (especially at ultrarelativistic energies), for two non-identical particles the two-particle annihilation sources – quark-antiquark and two-gluon ones – start playing a noticeable role and lead to the difference of the correlation tensor from zero. In particular, such a situation may arise, when the system passes through the “mixed phase” and – due to the multiple production of free quarks and gluons in the process of deconfinement of hadronic matter – the number of two-particle sources strongly increases.