Global Conservation Laws and Femtoscopy of Small Systems
Abstract
Description
It is important to understand, in detail, two-pion correlations measured in p+p and d+A collisions. In particular, one wishes to understand the femtoscopic correlations, in order to compare to similar measurements in heavy ion collisions. However, in the low-multiplicity final states of these systems, global conservation laws generate significant N-body correlations which project onto the two-pion space in non-trivial ways and complicate the femtoscopic analysis. We discuss a formalism to calculate and account for these correlations in collisions dominated by a single particle species (e.g. pions). We also discuss effects on two-particle correlations between non-identical particles, the understanding of which may be important in the study of femtoscopic space-time asymmetries.
17 pages, 15 figures; version 2 now shows explicitly that off-diagonal terms in covariance matrix vanish when using multivariate central limit theorem, in Section V; also, figures updated for clarity, references added, and discussion of binning effects moved to an appendix
17 pages, 15 figures; version 2 now shows explicitly that off-diagonal terms in covariance matrix vanish when using multivariate central limit theorem, in Section V; also, figures updated for clarity, references added, and discussion of binning effects moved to an appendix