Residual Bose-Einstein correlations in inclusiveπ + π − systems and theρ(770)0 line shape in multihadronicZ 0 decay

It is shown that in jet-like particle systems with multiplicities typical of multihadronicZ ⁰ decay, Bose-Einstein correlations acting between identical pions may have significant indirect effects on the phase space for pairs of non-identical pions. These effects have a direct bearing on experimental studies of Bose-Einstein correlations, particularly with regard to the use ofπ ⁺ π ^? distributions as reference samples. In addition they may distort the line shape of the broad ρ(770)⁰ resonance decaying viaπ ⁺ π ^?. The observed line shape of theρ ⁰ depends on the details of the production and decay amplitudes, and the shape ofπ ⁺ π ^? mass spectra in theρ ⁰ mass region may be affected by a number of other phenomena includingρ ⁰?ω interference and interference with coherentπ ⁺ π ^? backgrounds. Various models are discussed, with particular emphasis on studies of inclusive ρ(770)⁰ production inZ ⁰ decays at LEP.