$K_L \to \pi^0 \nu {\bar \nu}$ decay correlating with $\epsilon_K$ in high-scale SUSY

TL;DR

This paper investigates how high-scale supersymmetry (10-50 TeV) can significantly affect rare kaon decays and CP violation parameters, revealing potential deviations from Standard Model predictions based on recent collider constraints.

Contribution

It provides a detailed analysis of high-scale SUSY effects on rare kaon decays and epsilon_K, highlighting the dominant chargino and gluino contributions and their correlations.

Findings

Chargino contributions can enhance K_L to pi^0 nu nū decay by up to eight times.

Gluino box diagrams can dominate epsilon_K contributions up to 30%.

Even at 50 TeV scale, SUSY effects can double the K_L to pi^0 nu nū branching ratio.

Abstract

We have studied the contribution of the high-scale SUSY to the K_L to pi^0 nu{bar nu} and K^+ to pi^+ nu{bar nu} processes correlating with the CP violating parameter epsilon_K. Taking account of the recent LHC results for the Higgs discovery and the SUSY searches, we consider the high-scale SUSY at the 10-50 TeV scale in the framework of the non-minimal squark (slepton) flavor mixing. The Z penguin mediated the chargino dominates the SUSY contribution for these decays. At the 10 TeV scale of the SUSY, the chargino contribution can enhance the branching ratio of K_L to pi^0 nu{bar nu} in eight times compared with the SM predictions whereas the predicted branching ratio BR(K^+ to pi^+ nu {bar nu}) increases up to three times of the SM one. The gluino box diagram dominates the SUSY contribution of epsilon_K up to 30%. If the down-squark mixing is neglected compared with the up-squark mixing, the Z penguin mediated the chargino dominates both SUSY contributions of K_L to pi^0 nu {bar nu} and epsilon_K. Then, it is found a correlation between them, but the chargino contribution to epsilon_K is at most 3%. Even if the SUSY scale is 50TeV, the chargino process still enhances the branching ratio of K_L to pi^0 nu {bar nu} from the SM prediction in the factor two, and epsilon_K is deviated from the SM prediction in O(10%) through the gluino box diagram unless the down-squark mixing is suppressed. We also discuss the chargino contribution to K_L to pi^0 e^+e^- process.