Purity Calculation Method for Events Samples with Two Identical Particles

TL;DR

This paper introduces a novel background estimation method for events with two identical particles in high-energy physics, replacing standard 2D integration with a 1D approximation to improve purity calculation accuracy.

Contribution

The paper presents a new background calculation approach that does not rely on assumptions about background and signal shapes, demonstrated with Monte Carlo simulations.

Findings

High accuracy in purity estimation demonstrated with Monte Carlo data

Method outperforms standard 2D fit by reducing systematic bias

Applicable to analysis of double J/psi samples

Abstract

This paper studies a method of a two dimensional background calculation for an analysis of events with two particles of the same type registered in experiments in high-energy physics. The standard two-dimensional integration is replaced by an approximation of a specially constructed one-dimensional function. The number of the signal events is found by the subtraction of the background events. It allows calculating the purity of the selection. The procedure does not require a hypothesis about background and signal shapes. Monte Carlo examples of double J/psi samples are used to demonstrate high performance of the purity calculation method. A comparison of the method with standard two-dimensional fit of the signal revealed a systematic shift of the fit results to lower values.