Bose–Einstein correlations in charged current muon–neutrino interactions in the NOMAD experiment at CERN

Bose–Einstein correlations in one and two dimensions have been studied, with high statistics, in charged current muon–neutrino interaction events collected with the NOMAD detector at CERN. In one dimension the Bose–Einstein effect has been analyzed with the Goldhaber and the Kopylov–Podgoretskii phenomenological parametrizations. The Goldhaber parametrization gives the radius of the pion emission region RG=1.01±0.05(stat)+0.09−0.06(sys) fm and for the chaoticity parameter the value λ=0.40±0.03(stat)+0.01−0.06(sys). Using the Kopylov–Podgoretskii parametrization yields RKP=2.07±0.04(stat)+0.01−0.14(sys) fm and λKP=0.29±0.06(stat)+0.01−0.04(sys). Different parametrizations of the long-range correlations have been also studied. The two-dimensional shape of the source has been investigated in the longitudinal comoving frame. A significant difference between the transverse and the longitudinal dimensions is observed. The high statistics of the collected sample allowed the study of the Bose–Einstein correlations as a function of rapidity, charged particle multiplicity and hadronic energy. A weak dependence of both radius and chaoticity on multiplicity and hadronic energy is found.