Finite-size effect on two-particle production

Abstract

The formalism allowing one to account for the effect of a finite spacetime extent of a particle production region is given. Its applications to the lifetime measurement of hadronic atoms produced by a high-energy beam in a thin target, as well as to the femtoscopy techniques widely used to measure spacetime characteristics of the production processes, are discussed. The theoretical systematic errors due to the usual neglect of non-equal emission times in the pair center-of-mass system, the spacetime coherence and the residual charge are shown to be negligible.

Neutral kaon correlations in <FONT FACE=Symbol>Ö</FONT>S NN = 200 GeV Au+Au collisions at RHIC

“…The experimental correlation functions are fit using the Lednický & Lyuboshitz [28] model to take into account the effect of the strong FSI. The free parameters are the radius R characterizing the separation r * of the particle emission points in the pair rest frame, the normalization N, and λ.…”

“…The strong FSI has an important effect on neutral kaon correlations due to the near threshold resonances, f 0 (980) and a 0 (980) [28]. These resonances contribute to the K 0K0 channel and lead to the s-wave scattering length dominated by the imaginary part of ∼1 fm.…”

“…The correlation function is calculated as a mixture of the average squares of the properly symmetrized K 0 K 0 ,K 0K0 and non-symmetrized K 0K0 wave functions, weighted by the respective K 0 s K 0 s fractions. To average over the relative distance vector r * , the Lednický & Lyuboshitz analytical model [28] has been used, assuming r * is distributed according to Eq. (4) with a Gaussian radius R. The model assumes that the non-symmetrized wave functions Ψ −k * (r * ) describing the elastic transitions can be written as a superposition of the plane and spherical waves, the latter being dominated by the s-wave,…”

“…Neglecting the scattered waves for the K 0 K 0 andK 0K0 systems (the corresponding f (k * ) = 0) one obtains the following expression for the K 0 s K 0 s correlation function [28]:…”

“…Associating the amplitudes f I at isospin I = 0 and I = 1 with the resonances r = f 0 and a 0 respectively, one can write [28,30] …”