On the pair correlations of neutral K, D, B and B_s mesons with close momenta produced in inclusive multiparticle processes

Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia

^* e-mail: Valery.Lyuboshitz@jinr.ru

Published online: 3 April 2019

Abstract

The phenomenological structure of inclusive cross-sections of the production of two neutral K mesons in hadron–hadron, hadron–nucleus and nucleus–nucleus collisions is theoretically investigated taking into account the strangeness conservation in strong and electromagnetic interactions. Relations describing the dependence of the correlations of two short-lived and two long-lived neutral kaons $K_S^0{K}_S^0,K_L^0{K}_L^0$ and the correlations of “mixed” pairs $K_S^0{K}_L^0$ at small relative momenta upon the space-time parameters of the generation region of K⁰ and K̅⁰ mesons have been obtained. These relations involve the contributions of Bose-statistics and S -wave strong final-state interaction of two K⁰ (K̅⁰) mesons as well as of the K⁰ and K̅⁰ mesons, and also the additional contribution of transitions K⁺K^– → K⁰ K̅⁰, and they depend upon the relative fractions of generated pairs K⁰K⁰, K̅⁰ K̅⁰ and K⁰ K̅⁰. It is shown that under the strangeness conservation the correlation functions of the pairs $K_S^0{K}_S^0$ and $K_L^0{K}_L^0$, produced in the same inclusive process, coincide, and the difference between the correlation functions of the pairs $K_S^0{K}_S^0$ and $K_S^0{K}_L^0$ is conditioned exclusively by the production of the pairs of non-identical neutral kaons K⁰ K̅⁰.

For comparison, analogous correlations for the pairs of neutral heavy mesons D⁰, B⁰ and $B_s^0$, generated in multiple inclusive processes with charm (beauty) conservation, are also theoretically analyzed. These correlations are described by quite similar expressions: in particular, just as for K⁰ mesons, the correlation functions for the pairs of states with the same CP parity (R_{S S} = R_LL) and with different CP parity (R_{S L}) do not coincide, and the difference between them is conditioned exclusively by the production of pairs D⁰ D̅⁰, B⁰B̅⁰ and $B_s^0{\overline{B}}_s^0$. However, contrary to the case of K⁰ mesons, here the distinction of CP-even and CP-odd states encounters difficulties – due to the insignificant differences of their lifetimes and the relatively small probability of purely CP-even and CP-odd decay channels. Nevertheless, one may hope that it will become possible at future colliders.