CP Violation Tests of Alignment Models at LHCII

TL;DR

This paper investigates CP violation in alignment models at LHCII, deriving model-independent bounds and analyzing supersymmetric contributions, highlighting the importance of chargino effects and the limits of common approximation methods.

Contribution

It provides the first comprehensive analysis of CP violation bounds in alignment models, including exact SUSY calculations and the role of chargino contributions.

Findings

CP violation bounds in Kaon and D meson systems are correlated.

Chargino effects can dominate over gluino contributions in D-Dbar mixing.

Mass insertion approximation has limited applicability in certain SUSY scenarios.

Abstract

We analyse the low-energy phenomenology of alignment models both model-independently and within supersymmetric (SUSY) scenarios focusing on their CP violation tests at LHCII. Assuming that New Physics (NP) contributes to K-Kbar and D-Dbar mixings only through non-renormalizable operators involving SU(2)_L quark-doublets, we derive model-independent correlations among CP violating observables of the two systems. Due to universality of CP violation in Delta F=1 processes the bound on CP violation in Kaon mixing generically leads to an upper bound on the size of CP violation in D mixing. Interestingly, this bound is similar in magnitude to the current sensitivity reached by the LHCb experiment which is starting now to probe the natural predictions of alignment models. Within SUSY, we perform an exact analytical computation of the full set of contributions for the D-Dbar mixing amplitude. We point out that chargino effects are comparable and often dominant with respect to gluino contributions making their inclusion in phenomenological analyses essential. As a byproduct, we clarify the limit of applicability of the commonly used mass insertion approximation in scenarios with quasi-degenerate and split squarks.