Axion-like particles and sterile neutrinos solve the B→ Kνν̅ and B→ πK puzzles
Abstract
The recent measurement of the branching ratio of B+ → K+ + inv (where ``inv'' denotes invisible states) by the Belle II collaboration is enhanced relative to the standard model expectation by 2.7σ. An older puzzle persists in measurements of the branching ratios and CP asymmetries of $B \to πK $ decays. We address these two anomalies in flavor-changing neutral current B decays, with a short-lived axion-like particle (ALP) with mass close to that of the π0. In the model with the minimum number of new couplings, the ALP has couplings to the photon, top quark and a heavy sterile neutrino. The ALP contributes to the $B \to π^0 K $ decays by mixing with the π0. It contributes to B+ → K+ + inv by its off-shell coupling to sterile neutrino pairs. The model can explain the excess in the total rate, but not the observed distribution of signal events. We make predictions for all B → K(*) + inv modes and for the rare kaon decays, K+ → π+ + inv and KL → π0 + inv. We find an appreciable contribution to the magnetic moment of the muon, and negligible contributions to the magnetic moment of the electron and b → s e+ e-.
Versions
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BibTeX
@misc{bhattacharya2026axionlike,
title = {{Axion-like particles and sterile neutrinos solve the $B\to Kν\barν$ and $B\to πK$ puzzles}},
author = {Bhubanjyoti Bhattacharya and Alakabha Datta and Girish Kumar and Danny Marfatia},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2605.24713},
eprint = {2605.24713},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.24713},
}
RIS
TY - UNPB
TI - Axion-like particles and sterile neutrinos solve the B→ Kνν̅ and B→ πK puzzles
AU - Bhubanjyoti Bhattacharya
AU - Alakabha Datta
AU - Girish Kumar
AU - Danny Marfatia
PY - 2026
DA - 2026/08/11
PB - arXiv
DO - 10.48550/arxiv.2605.24713
UR - https://arxiv.org/abs/2605.24713
AB - The recent measurement of the branching ratio of B^+ → K^+ + inv (where ``inv'' denotes invisible states) by the Belle II collaboration is enhanced relative to the standard model expectation by 2.7σ. An older puzzle persists in measurements of the branching ratios and CP asymmetries of $B \to πK $ decays. We address these two anomalies in flavor-changing neutral current B decays, with a short-lived axion-like particle (ALP) with mass close to that of the π^0. In the model with the minimum number of new couplings, the ALP has couplings to the photon, top quark and a heavy sterile neutrino. The ALP contributes to the $B \to π^0 K $ decays by mixing with the π^0. It contributes to B^+ → K^+ + inv by its off-shell coupling to sterile neutrino pairs. The model can explain the excess in the total rate, but not the observed distribution of signal events. We make predictions for all B → K^(*) + inv modes and for the rare kaon decays, K^+ → π^+ + inv and K_L → π^0 + inv. We find an appreciable contribution to the magnetic moment of the muon, and negligible contributions to the magnetic moment of the electron and b → s e^+ e^-.
ER -