Correlating New Physics Effects in Semileptonic $\Delta C = 1$ and $\Delta S = 1$ Processes

TL;DR

This paper constrains new physics effects in semileptonic and leptonic decays across multiple mesons and nuclear processes, using a flavor covariant approach to relate effects in different decays and identify CP phases.

Contribution

It introduces a flavor covariant framework to connect new physics effects in $K$, $D$, and nuclear decays, deriving constraints and predictions for maximal effects.

Findings

Constraints on dimension-6 operators from decay rates and CP-odd observables.

Predictions of maximal new physics effects in $D$ decays based on $K$ decay constraints.

Identification of universal CP phases of new physics.

Abstract

We present constraints on the left-handed dimension-6 interactions that contribute to semileptonic and leptonic decays of $K$, $D$, pions and to nuclear beta decay. We employ the flavour covariant description of the effective couplings, identify universal CP phases of New Physics and derive constraints from decay rates and CP-odd quantities. As a result, we can predict the maximal effects of such flavoured NP in $D$ decays from stringent $K$ decay constraints and vice-versa.