HBT shape analysis with q-cumulants【荐】.pdfVIP

H.C. Eggers and P. Lipa 1 HBT shape analysis with q-cumulants H.C. Eggers1 and P. Lipa2 1 Department of Physics, University of Stellenbosch, 7602 Stellenbosch, South Africa 2 Arizona Research Laboratories, Division of Neural Systems, Memory and Ageing, University of Arizona, Tucson AZ 85724, USA. Taking up and extending earlier suggestions, we show how two- and threedimensional shapes of second- order HBT correlations can be described in a multivariate Edgeworth expansion around gaussian ellipsoids, with expansion coefficients, identified as the cumulants of pair momentum difference q, acting as shape parameters. 7 Off-diagonal terms dominate both the character and magnitude of shapes. Cumulants can be measured directly 0 and so the shape analysis has no need for fitting. 0 2 Keywords: particle correlations, intensity interferometry r a I. INTRODUCTION more traditional continuous version [12] with a gaussian ref- M erence f 0 . For the purpose of analysing the shape of the ex- 9 Early measurements of the Hanbury-Brown Twiss (HBT) perimental correlation function in HBT, we hence define the 2 effect made use of momentum differences in one dimension, measured nongaussian probability density as