Supersymmetric Explanation of CP Violation in K→ππ Decays

Recent progress in the determination of hadronic matrix elements has revealed a tension between the measured value of ε_{K}^{'}/ε_{K}, which quantifies direct CP violation in K→ππ decays, and the standard-model prediction. The well-understood indirect CP violation encoded in the quantity ε_{K} typically precludes large new-physics contributions to ε_{K}^{'}/ε_{K} and challenges such an explanation of the discrepancy. We show that it is possible to cure the ε_{K}^{'}/ε_{K} anomaly in the minimal supersymmetric standard model with squark masses above 3 TeV without overshooting ε_{K}. This solution exploits two features of supersymmetry: the possibility of large isospin-breaking contributions (enhancing ε_{K}^{'}) and the Majorana nature of gluinos (permitting a suppression of ε_{K}). Our solution involves no fine-tuning of CP phases or other parameters.