Measurement of CP asymmetries in neutralino production at the ILC

TL;DR

This study evaluates the potential to measure CP asymmetries in neutralino production at the ILC, using detailed simulations and kinematic reconstruction to achieve precise results within the MSSM framework.

Contribution

It introduces a comprehensive simulation-based method to measure CP asymmetries in neutralino production, demonstrating effective background reduction and applicability to various scenarios.

Findings

Achieved 10% accuracy in measuring CP asymmetry with 500 fb^-1.

Validated kinematic reconstruction for signal-background separation.

Demonstrated method's broad applicability to different scenarios.

Abstract

We study the prospects to measure the CP-sensitive triple-product asymmetries in neutralino production e+e- -> ~chi^0_i ~chi^0_1 and subsequent leptonic two-body decays ~chi^0_i -> ~l_R l, ~l_R -> ~chi^0_1 l, for l=e, mu, within the Minimal Supersymmetric Standard Model. We include a full detector simulation of the International Large Detector for the International Linear Collider. The simulation was performed at a center-of-mass energy of sqrt{s}=500 GeV, including the relevant Standard Model background processes, a realistic beam energy spectrum, beam backgrounds and a beam polarization of 80% and -60% for the electron and positron beams, respectively. In order to effectively disentangle different signal samples and reduce SM and SUSY backgrounds we apply a method of kinematic reconstruction. Assuming an integrated luminosity of 500 fb^-1 collected by the experiment and the performance of the current ILD detector, we arrive at a relative measurement accuracy of 10% for the CP-sensitive asymmetry in our scenario. We demonstrate that our method of signal selection using kinematic reconstruction can be applied to a broad class of scenarios and it allows disentangling processes with similar kinematic properties.