The effect of resonance production on angular correlations

Angular correlations between pairs of secondary particles emitted in 4- and 6-prong events of π+p interactions at 16 GeV/c are studied as functions of the effective mass M of the two particles involved. It is argued that this is superior to the usual technique of studying correlations as functions of Δy (the difference in the rapidities of two particles), because effects of different origins such as resonance production of Bose-Einstein interference, which all occur predominantly at Δy approximately 0, are well separated when plotted in terms of the mass. It is shown that the angular correlations are strongly affected by the production of two-particle resonances such as rho0, f, and g mesons for (π+π-) pairs, and Δ++(1232) and Δ++(1890) isobars for the (pπ+) pairs. A variable D(M) is proposed, related to the difference in angular correlations of pairs of like and unlike charges, which is shown to be effective in enhancing resonance signals and could be useful also at higher energies. (Auth.)