Bose-Einstein correlations in one and two dimensions in deep inelastic scattering.

Bose–Einstein correlations in one and two dimensions have been studied in deep inelastic ep scattering events measured with the ZEUS detector at HERA using an integrated luminosity of 121 pb−1. The correlations are independent of the virtuality of the exchanged photon, Q2, in the range 0.1<Q2<8000 GeV2. There is no significant difference between the correlations in the current and target regions of the Breit frame for Q2>100 GeV2. The two-dimensional shape of the particle-production source was investigated, and a significant difference between the transverse and the longitudinal dimensions of the source is observed. This difference also shows no Q2 dependence. The results demonstrate that Bose–Einstein interference, and hence the size of the particle-production source, is insensitive to the hard subprocess.