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Main Authors: Yan, Xin-Shuai, Liu, Wen-Feng, Chang, Qin, Yang, Ya-Dong
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2601.18147
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author Yan, Xin-Shuai
Liu, Wen-Feng
Chang, Qin
Yang, Ya-Dong
author_facet Yan, Xin-Shuai
Liu, Wen-Feng
Chang, Qin
Yang, Ya-Dong
contents The recent evidence for the decay $B^+ \to K^+ ν\barν$ reported by the Belle II collaboration, combined with the existing constraints on the neutral mode $B^0 \to K^{*0} ν\barν$, implies a deviation from the Standard Model prediction that necessitates New Physics contributions to both left- and right-handed vector currents. We perform a systematic topological classification of renormalizable one-loop completions capable of generating the required dimension-six operators while forbidding tree-level mediation. Based on this classification, we identify and construct two minimal benchmark scenarios -- a scalar-rich model and a fermion-rich model -- and perform a comprehensive phenomenological analysis. Our study demonstrates that while these one-loop models can yield enhancements in the $b \to s ν\barν$ branching fractions, the attainable magnitudes are significantly restricted by the combined effects of loop suppression and complementary flavor constraints, limiting their ability to fully accommodate the current anomaly.
format Preprint
id arxiv_https___arxiv_org_abs_2601_18147
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Systematic classification of one-loop models addressing the $b \to s ν\barν$ anomaly
Yan, Xin-Shuai
Liu, Wen-Feng
Chang, Qin
Yang, Ya-Dong
High Energy Physics - Phenomenology
The recent evidence for the decay $B^+ \to K^+ ν\barν$ reported by the Belle II collaboration, combined with the existing constraints on the neutral mode $B^0 \to K^{*0} ν\barν$, implies a deviation from the Standard Model prediction that necessitates New Physics contributions to both left- and right-handed vector currents. We perform a systematic topological classification of renormalizable one-loop completions capable of generating the required dimension-six operators while forbidding tree-level mediation. Based on this classification, we identify and construct two minimal benchmark scenarios -- a scalar-rich model and a fermion-rich model -- and perform a comprehensive phenomenological analysis. Our study demonstrates that while these one-loop models can yield enhancements in the $b \to s ν\barν$ branching fractions, the attainable magnitudes are significantly restricted by the combined effects of loop suppression and complementary flavor constraints, limiting their ability to fully accommodate the current anomaly.
title Systematic classification of one-loop models addressing the $b \to s ν\barν$ anomaly
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2601.18147