Multiplicity dependence of Bose-Einstein correlations in hadronic Z(0) decays

Bose-Einstein correlations between like charged track pairs have been studied using a sample of approximately 3.6 million multihadronic Z(0) decays collected with the OPAL detector at LEP. The radius of the emitting source R and the chaoticity parameter lambda were studied using two parametrisations, the Goldhaber (G) parametrisation and the one-dimensional Kopylov-Podgoretskii (KP) parametrisation. The radii R(G) and R(KP) are found to increase linearly with the average observed charged multiplicity n(ch), with changes with respect to a unit increase in n(ch) of 1\[R(G)] Delta R(G)\Delta n(ch) = (3.6 +/- 0.6) . 10(-3) and 1\[R(KP)] Delta R(KP)\Delta n(ch) = (3.4 +/- 1.0) . 10(-3), where the [R] are the radius values measured in the the inclusive event sample. The chaoticity parameters lambda(G) and lambda(KP) decrease with increasing charged multiplicity. It is shown that the increase of R with multiplicity may be connected with differences between two- and three-jet events.