Discriminating Tauphilic Leptoquark Explanations of the $B$ Anomalies via $K\to πν\barν$ and $B\to Kν\barν$

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Autori principali: Crivellin, Andreas, Iguro, Syuhei, Kitahara, Teppei
Natura: Preprint
Pubblicazione: 2025
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author Crivellin, Andreas
Iguro, Syuhei
Kitahara, Teppei
author_facet Crivellin, Andreas
Iguro, Syuhei
Kitahara, Teppei
contents Leptoquark models are prime candidates for new physics (NP) explanations of the long-standing anomalies in semi-leptonic $B$ decays; $b\to c τ\barν$ (encoded in $R(D^{(\ast)})$) and $b\to s\ell\bar\ell (\ell=e,μ)$ transitions. Furthermore, Belle II and NA62 reported weaker-than-expected limits on $B^+ \to K^+ ν\barν$ and $K^+ \to π^+ ν\barν$, respectively. While the $R(D^{(\ast)})$ and $b\to s\ell \bar\ell$ measurements can be explained with NP contributions at the $O(10\%)$ level, the neutrino channels suggest that the NP effect could be comparable in size to the Standard Model one. In this context, we consider the two types of leptoquark models with minimal sets of the couplings that can best describe the semi-leptonic $B$ anomalies and lead at the same time to effects in the neutrino modes, the singlet-triplet scalar leptoquark model ($S_1+S_3$) and the singlet vector leptoquark model ($U_1$). More specifically, the neutrino channels pose non-trivial constraints on the parameter space, and we find that large effects (i.e., accounting for the current central value) in $B\to K^{(*)}ν\barν$ are only possible in the $S_1+S_3$ setup, while both models can account for the central value of $K^+\to π^+ν\barν$.
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id arxiv_https___arxiv_org_abs_2505_05552
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Discriminating Tauphilic Leptoquark Explanations of the $B$ Anomalies via $K\to πν\barν$ and $B\to Kν\barν$
Crivellin, Andreas
Iguro, Syuhei
Kitahara, Teppei
High Energy Physics - Phenomenology
High Energy Physics - Experiment
Leptoquark models are prime candidates for new physics (NP) explanations of the long-standing anomalies in semi-leptonic $B$ decays; $b\to c τ\barν$ (encoded in $R(D^{(\ast)})$) and $b\to s\ell\bar\ell (\ell=e,μ)$ transitions. Furthermore, Belle II and NA62 reported weaker-than-expected limits on $B^+ \to K^+ ν\barν$ and $K^+ \to π^+ ν\barν$, respectively. While the $R(D^{(\ast)})$ and $b\to s\ell \bar\ell$ measurements can be explained with NP contributions at the $O(10\%)$ level, the neutrino channels suggest that the NP effect could be comparable in size to the Standard Model one. In this context, we consider the two types of leptoquark models with minimal sets of the couplings that can best describe the semi-leptonic $B$ anomalies and lead at the same time to effects in the neutrino modes, the singlet-triplet scalar leptoquark model ($S_1+S_3$) and the singlet vector leptoquark model ($U_1$). More specifically, the neutrino channels pose non-trivial constraints on the parameter space, and we find that large effects (i.e., accounting for the current central value) in $B\to K^{(*)}ν\barν$ are only possible in the $S_1+S_3$ setup, while both models can account for the central value of $K^+\to π^+ν\barν$.
title Discriminating Tauphilic Leptoquark Explanations of the $B$ Anomalies via $K\to πν\barν$ and $B\to Kν\barν$
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2505.05552