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Smallness of charm-loop effects in $B \to K^{(*)} ℓ ℓ$ at low $q^{2}$ : Light-meson distribution-amplitude analysis

Namit Mahajan^*

Dayanand Mishra ^†

Theoretical Physics Division, Physical Research Laboratory, Ahmedabad 380009, India

Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400001, India

^*Contact author: nmahajan@prl.res.in, mahajannamit@gmail.com
^†Contact author: dayanand.mishra@tifr.res.in

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Phys. Rev. D 111, L031504 – Published 24 February, 2025

DOI: https://doi.org/10.1103/PhysRevD.111.L031504

Abstract

The nonlocal effects originating from the charm quark loops at dilepton invariant masses smaller than the charmonium threshold in $B \to K ℓ ℓ$ are evaluated with light-meson distribution amplitudes. The revised estimates with $B$ -meson distribution amplitude within a light cone sum rule approach yielded results about three orders smaller than the original computation. In view of the importance of these nonfactorizable soft gluon effects, both conceptually and phenomenologically, an independent evaluation is necessary. It is found that to twist-4 accuracy, these soft gluon effects vanish when evaluated employing the kaon distribution amplitude. Similar results hold for $B \to K^{*} ℓ ℓ$ to the leading twist. This eliminates one of the major sources of potential uncertainty which usually makes it difficult for a clear case of new physics, should the data show deviations from the standard model.

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Phys. Rev. D 111, L031504– Published 24 February, 2025

Vol. 111, Iss. 3 — 1 February 2025

Received 24 September 2024
Accepted 1 February 2025

DOI: https://doi.org/10.1103/PhysRevD.111.L031504

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Smallness of charm-loop effects in $B \to K^{(*)} ℓ ℓ$ at low $q^{2}$ : Light-meson distribution-amplitude analysis

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Smallness of charm-loop effects in B→K(*)ℓℓ at low q2: Light-meson distribution-amplitude analysis

Abstract

Physics Subject Headings (PhySH)

Article Text

References (51)

Smallness of charm-loop effects in $B \to K^{(*)} ℓ ℓ$ at low $q^{2}$ : Light-meson distribution-amplitude analysis