From B-meson anomalies to Kaon physics with scalar leptoquarks

TL;DR

This paper explores how scalar leptoquarks could simultaneously explain B-meson anomalies and affect Kaon decay observables, revealing tensions with experimental bounds and examining flavor symmetry assumptions.

Contribution

It establishes a connection between B-meson anomalies and Kaon physics via scalar leptoquarks within a specific flavor symmetry framework, analyzing experimental constraints and their implications.

Findings

NA62 bounds challenge the model under certain flavor assumptions

Current limits on Kaon decay modes can be satisfied by the model

Relaxing flavor assumptions broadens viable parameter space for Kaon observables

Abstract

In this work we study possible connections between $B$-meson anomalies and Kaon physics observables in the context of combined solutions with the singlet and triplet scalar leptoquarks $S_1$ and $S_3$. By assuming a flavor structure for the leptoquark couplings dictated by a minimally broken $U(2)^5$ flavor symmetry we can make a sharp connection between these two classes of observables. We find that the bound on $\mathcal{B}(K^+ \rightarrow \pi^+ \nu\nu)$ from NA62 puts already some tension in the model, while the present limits on $\mathcal{B}(K_L \rightarrow \mu^+ \mu^-)$ and $\mu \to e$ conversion in nuclei can be saturated. Relaxing instead the flavor assumption we study what values for $\mathcal{B}(K^+ \rightarrow\pi^+ \nu\nu)$, as well as for $\mathcal{B}(K_L \rightarrow\pi^0 \nu\nu)$ and $\mathcal{B}(K_{L,S} \rightarrow\mu^+ \mu^-)$, are viable compatibly with all other phenomenological constraints.