Generalized bunching parameters and multiplicity fluctuations in restricted phase-space bins

Abstract

Experimental aspects of the use of bunching parameters are discussed. Special attention is paid to the behavior expected for the case of purely statistical fluctuations. We studied bin-averaged bunching parameters and propose a generalization of bunching parameters, making use of the interparticle distance-measure technique. The proposed method opens up the possibility of carrying out a comprehensive and sensitive investigation of multiplicity fluctuations inside jets.

Local multiplicity fluctuations in hadronic Z decay

“…In order to improve the accuracy we use the bin-averaged \horizontal" NFMs [1] and BPs [13,14]: The NFM of order q is calculated using the standard denition:…”

“…From an experimental point of view, the BPs have several advantages [14]: (1) They are less severely aected by statistical bias than the NFMs, since the BP of order q depends only on the behaviour of the multiplicity distribution near multiplicity n = q 1; (2) for the calculation of the BP of order q, one only needs to beable to resolve q particles in a bin, rather than all particles as for the NFMs; and (3) many systematic errors cancel in the ratio of probabilities.…”

“…To remedy this problem with the NFMs, and in addition to increase the eective statistics, normalized density strip integrals have been proposed [15]. Analogously, a new type of bunching parameter has been suggested [14], which can beused to study the uctuation of the numberof spikes (dened in section 2) perevent. Generalized integral bunching parameters (GBPs) are dened by…”

“…An alternative to the NFMs is provided by bunching parameters (BPs), q (), [13,14] which are dened by q () = q q 1 P q ( ) P q 2 ( ) P 2 q 1 ( ) ;q = 2 ; 3 ; : : : :…”

“…The statistical errors for the GBPs are derived according to the expression obtained in ref. [14]. Systematic errors on the raw quantities have been estimated by varying the event-and track-selection criteria.…”