Corrections to models of B-physics decay anomalies

TL;DR

This paper investigates the 4321 class of models addressing B-meson decay anomalies, emphasizing the importance of NLO corrections and flavor violation effects from vector-like fermions for precise data-model compatibility.

Contribution

It introduces and analyzes the 4321 models, highlighting the significance of NLO effects and flavor violation in explaining B-physics decay anomalies.

Findings

Large NLO corrections from the U_1 leptoquark coupling to third-generation fermions.

New flavor violation sources from vector-like fermions affecting loop-level processes.

Emphasizes the necessity of NLO calculations for accurate compatibility tests.

Abstract

Motivated by the recent anomalies observed in semileptonic decays of B-mesons, the class of models denoted as "4321" is introduced and analysed. The importance of calculating next-to-leading-order (NLO) effects in performing precise compatibility tests of data with 4321 predictions is discussed. On the one hand, the coupling of the $U_1 \sim (\textbf{3},\textbf{1})_{2/3}$ leptoquark appearing in the spectrum to the third-generation fermions is large, giving rise to sizable NLO corrections in the relevant semileptonic operators. On the other hand, the new source of flavor violation is introduced with the vector-like fermions, resulting in the processes whose relevance can only be quantified at the loop order.