QED Corrections to B^−→ τ^−ν̅_τ

Abstract

Using a sequence of effective field theories (EFTs), we calculate the rate for the leptonic decay B⁻→ τ⁻ν̅_τ(γ ) including real and virtual QED corrections, with a cut Ecut ≪ ΛQCD imposed on electromagnetic radiation in the B-meson rest frame. We establish a factorization theorem for the rate and evaluate it at 𝒪(α), resumming the leading logarithmic corrections to all orders in perturbation theory. The large mass mτ allows us to treat the tau lepton as a heavy fermion below μ ~ mB ~ mτ, leading to an EFT construction that is structurally different and noticeably simpler than that for the muon case [1]. In particular, hadron-structure dependent QED corrections can be described in terms of QED-induced B− → τ− form factors, which should be calculable on the lattice. Our analysis includes the leading ΛQCD/mτ corrections as well as the leading corrections in Ecut/ΛQCD. We show that contributions of the form ΛQCD m_B/m_τ², which are naively sizable, cancel among each other. Contrary to the muon channel, structure-dependent corrections involving BB*γ transitions are numerically negligible for the tau case. The remaining logarithmic dependence on Ecut is mild. We estimate that the present uncertainty in the calculation of the structure-dependent QED corrections is about 0.5% of the rate. As a byproduct, we present a state-of-the-art prediction for the lepton flavor universality ratio of the tau and muon channels.

Cite

BibTeX RIS

BibTeX

@article{cornella2026corrections,
  title = {{QED Corrections to $$ B^-\to \tau^-\overline\nu_\tau  $$}},
  author = {Claudia Cornella and Max Ferré and Matthias König and Matthias Neubert},
  journal = {Journal of High Energy Physics},
  year = {2026},
  month = nov,
  doi = {10.1007/jhep11(2026)046},
  url = {https://link.springer.com/article/10.1007/JHEP11(2026)046},
  note = {CC BY 4.0},
}

RIS

TY  - JOUR
TI  - QED Corrections to B^−→ τ^−ν̅_τ 
AU  - Claudia Cornella
AU  - Max Ferré
AU  - Matthias König
AU  - Matthias Neubert
PY  - 2026
DA  - 2026/11/05
JO  - Journal of High Energy Physics
DO  - 10.1007/jhep11(2026)046
UR  - https://link.springer.com/article/10.1007/JHEP11(2026)046
AB  - Using a sequence of effective field theories (EFTs), we calculate the rate for the leptonic decay B^−→ τ^−ν̅_τ(γ ) including real and virtual QED corrections, with a cut Ecut ≪ ΛQCD imposed on electromagnetic radiation in the B-meson rest frame. We establish a factorization theorem for the rate and evaluate it at 𝒪(α), resumming the leading logarithmic corrections to all orders in perturbation theory. The large mass mτ allows us to treat the tau lepton as a heavy fermion below μ ~ mB ~ mτ, leading to an EFT construction that is structurally different and noticeably simpler than that for the muon case [1]. In particular, hadron-structure dependent QED corrections can be described in terms of QED-induced B− → τ− form factors, which should be calculable on the lattice. Our analysis includes the leading ΛQCD/mτ corrections as well as the leading corrections in Ecut/ΛQCD. We show that contributions of the form ΛQCD m_B/m_τ^2, which are naively sizable, cancel among each other. Contrary to the muon channel, structure-dependent corrections involving BB*γ transitions are numerically negligible for the tau case. The remaining logarithmic dependence on Ecut is mild. We estimate that the present uncertainty in the calculation of the structure-dependent QED corrections is about 0.5% of the rate. As a byproduct, we present a state-of-the-art prediction for the lepton flavor universality ratio of the tau and muon channels.
SN  - 1029-8479
ER  -