Beam polarization effects in the radiative production of lightest neutralinos in $e^+ e^-$ collisions in supersymmetric grand unified models

TL;DR

This paper investigates how beam polarization influences the production of lightest neutralinos in electron-positron collisions within supersymmetric grand unified models, analyzing signal and background processes at the International Linear Collider.

Contribution

It provides a comprehensive analysis of neutralino production in SU(5) and SO(10) GUT models, including radiative corrections and polarization effects, to evaluate experimental observability.

Findings

Beam polarization significantly affects the neutralino production cross section.

Background processes from neutrino and sneutrino production are thoroughly analyzed.

Differences in signal dependence on GUT group and representations are identified.

Abstract

We study the production of the lightest neutralinos in the process $e^+ e^- \rightarrow \chi_1^0 \chi_1^0 \gamma$ in supersymmetric grand unified models for the International Linear Collider Energies with longitudinally polarized beams. We consider cases where the standard model gauge group is unified into the grand unified gauge groups SU(5), or SO(10). We have carried out a comprehensive study of this process in the SU(5) and SO(10) grand unified theories which includes the QED radiative corrections. We compare and contrast the dependence of the signal cross section on the grand unified gauge group, and on the different representations of the grand unified gauge group, when the the electron and positron beams are longitudinally polarized. To assess the feasibility of experimentally observing the radiative production process, we have also considered in detail the background to this process coming from the radiative neutrino production process $e^+ e^- \rightarrow \nu \bar\nu \gamma$ with longitudinally polarized electron and positron beams. In addition we have also considered the supersymmetric background coming from the radiative production of scalar neutrinos in the process $e^+ e^- \rightarrow \tilde \nu \tilde\nu^* \gamma$ with longitudinally polarized beams. The process can be a major background to the radiative production of neutralinos when the scalar neutrinos decay invisibly.