Residual Bose-Einstein Correlations and the Soeding Model

Bose-Einstein correlations between identical pions close in phase-space is thought to be responsible for the observed distortion in mass spectra of non-identical pions. For example in the decays ρ0 → π+π- and ρ± → π±π0, such distortions are a residual effect where the pions from the ρ decay interact with other identical pions that are close in phase-space. Such interactions can be significant in, for example, hadronic decays of Z bosons where pion multiplicities are high, and resonances such as mesons decay with a very short lifetime thereby creating pions that are close to prompt pions created directly. We present the Soeding model and show that it has been used successfully to model distortions in π±π0 mass spectra in hadronic Z decays recorded by ALEPH. (author)