Isospin sum rules and charge correlations in e+e− → hadrons and $$\overline {\mathcal{N}} {\mathcal{N}}$$ annihilationannihilation

Abstract

One-particle and two-particle charge distributions are studied for a system ofn pions of total isospinI = 0 andI = 1. Isospin invariance is fully exploited by using isospin inclusive sum rules, and is combined with positivity to give bounds on measurable quantities. The parameters which are not determined by pure isospin invariance are then expressed in terms of the partition [N1,N2,N3] of the numbern of pions which identifies the symmetry under permutations of the charge state. The correlation parameterf+, defined by the equation 〈n+(n+−1)〉 − 〈n+〉2 =f+〈n+〉, is shown to be a useful and sensitive tool for determining the charge state of the system.