Covariant Description of Flavor Conversion in the LHC Era

TL;DR

This paper introduces a covariant formalism for analyzing flavor and CP violation in the quark sector, providing a transparent, model-independent way to derive bounds on new physics from LHC data and flavor experiments.

Contribution

It presents a novel covariant basis that makes the symmetry structure of flavor violation transparent, enabling robust, assumption-free bounds on new physics models from collider and flavor data.

Findings

LHC can exclude new physics up to 0.6-7.6 TeV depending on coupling strength.

Current constraints on Delta t=1 processes are weak.

Flavor violation bounds from D-meson CP violation are significant.

Abstract

A simple covariant formalism to describe flavor and CP violation in the left-handed quark sector in a model independent way is provided. The introduction of a covariant basis, which makes the standard model approximate symmetry structure manifest, leads to a physical and transparent picture of flavor conversion processes. Our method is particularly useful to derive robust bounds on models with arbitrary mechanisms of alignment. Known constraints on flavor violation in the K and D systems are reproduced in a straightforward manner. Assumptions-free limits, based on top flavor violation at the LHC, are then obtained. In the absence of signal, with 100 fb^{-1} of data, the LHC will exclude weakly coupled (strongly coupled) new physics up to a scale of 0.6 TeV (7.6 TeV), while at present no general constraint can be set related to Delta t=1 processes. LHC data will constrain Delta F=2 contributions via same-sign tops signal, with a model independent exclusion region of 0.08 TeV (1.0 TeV). However, in this case, stronger bounds are found from the study of CP violation in D-bar D mixing with a scale of 0.57 TeV (7.2 TeV). In addition, we apply our analysis to models of supersymmetry and warped extra dimension. The minimal flavor violation framework is also discussed, where the formalism allows to distinguish between the linear and generic non-linear limits within this class of models.