Binned and Unbinned Transverse Single Spin Asymmetry Extraction, including Background Subtraction and Unfolding

TL;DR

This paper introduces comprehensive methods for extracting transverse single-spin asymmetries in experiments, addressing challenges like polarization variability, background noise, and detector effects through binned/unbinned analysis and unfolding techniques.

Contribution

It presents novel general methods for asymmetry extraction that incorporate background subtraction and unfolding, applicable to complex experimental conditions.

Findings

Effective background subtraction techniques demonstrated.

Unfolding methods improve accuracy of asymmetry measurements.

Applicable to experiments with variable polarization and detector smearing.

Abstract

The determination of transverse single-spin asymmetries in experiments involving polarized targets and/or beams may encounter challenges when (1) the magnitude of the polarization varies greatly with time, (2) the polarization magnitude is not the same for each spin state, (3) different integrated luminosities occur for different spin states or different target materials, and/or (4) some kinematic variables require unfolding; these are just a few examples. We present general methods of determining the asymmetry based on both binned analysis and unbinned maximum likelihood optimization, incorporating the unfolding of kinematic variables that are smeared by detector effects, and also including the possibility of background subtraction.