Probing New Physics with b → u ℓ νℓ induced decays
Abstract
We analyze B- → μ- ν̅μ, B̅0 → π+ μ-ν̅μ, and B- → ρ0 μ- ν̅μ decays using the data on binned branching fractions recently measured by Belle II Collaboration for the semileptonic modes. We extend the low-energy Hamiltonian governing b → u ℓ ν̅ℓ transitions to include the full set of dimension-six, Lorentz-invariant operators with left-handed neutrinos, consistent with the Standard Model Effective Field Theory (SMEFT) framework. The Wilson coefficients are treated as complex, lepton-flavor-dependent effective couplings. Since the three selected channels are sensitive to different non-standard structures, we perform a combined analysis using Monte Carlo methods to constrain the New Physics couplings for three benchmark values of |Vub|. We find that, while the Standard Model remains broadly compatible with the data, some of the couplings show a mild preference for non-zero values.
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BibTeX
@misc{cuia2026probing,
title = {{Probing New Physics with $b \to u \ell ν_\ell$ induced decays}},
author = {Maria Letizia Di Cuia and Davide Milillo},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29707},
eprint = {2610.29707},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29707},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Probing New Physics with b → u ℓ ν_ℓ induced decays
AU - Maria Letizia Di Cuia
AU - Davide Milillo
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.29707
UR - https://arxiv.org/abs/2610.29707
AB - We analyze B^- → μ^- ν̅_μ, B̅^0 → π^+ μ^-ν̅_μ, and B^- → ρ^0 μ^- ν̅_μ decays using the data on binned branching fractions recently measured by Belle II Collaboration for the semileptonic modes. We extend the low-energy Hamiltonian governing b → u ℓ ν̅_ℓ transitions to include the full set of dimension-six, Lorentz-invariant operators with left-handed neutrinos, consistent with the Standard Model Effective Field Theory (SMEFT) framework. The Wilson coefficients are treated as complex, lepton-flavor-dependent effective couplings. Since the three selected channels are sensitive to different non-standard structures, we perform a combined analysis using Monte Carlo methods to constrain the New Physics couplings for three benchmark values of |V_ub|. We find that, while the Standard Model remains broadly compatible with the data, some of the couplings show a mild preference for non-zero values.
ER -