R-Parity Violating Supersymmetry Explanation for Large t tbar Forward-Backward Asymmetry

TL;DR

This paper proposes a supersymmetric model involving R-parity violation to explain the large forward-backward asymmetry in top quark pair production, consistent with current collider constraints and testable with future LHC data.

Contribution

It introduces a specific R-parity violating supersymmetric mechanism involving a right-handed sbottom to account for the asymmetry, with detailed predictions compatible with existing experiments.

Findings

Sbottom mass between 300 and 1200 GeV can explain asymmetry

Predicted LHC charge asymmetry is small but detectable

Additional t tbar cross-section contributions offer further tests

Abstract

We propose a supersymmetric explanation for the anomalously high forward backward asymmetry in top pair production measured by CDF and D0. We suppose that it is due to the t-channel exchange of a right-handed sbottom which couples to d_R and t_R, as is present in the R-parity violating minimal supersymmetric standard model. We show that all Tevatron and LHC experiments' t tbar constraints may be respected for a sbottom mass between 300 and 1200 GeV, and a large Yukawa coupling >2.2, yielding A_{FB} up to 0.18. The non Standard Model contribution to the LHC charge asymmetry parameter is Delta A_C^y=0.017-0.045, small enough to be consistent with current measurements but non-zero and positive, allowing for LHC confirmation in the future within 20 fb^-1. A small additional contribution to the LHC t tbar production cross-section is also predicted, allowing a further test. We estimate that 10 fb^-1 of LHC luminosity would be sufficient to rule out the proposal to 95% confidence level, if the measurements of the t tbar cross-section turn out to be centred on the Standard Model prediction.