https://doi.org/10.1140/epjs/s11734-023-01012-2
Review
Review of semileptonic B anomalies
1
DAMTP, University of Cambridge, Wilberforce Road, CB3 0WA, Cambridge, UK
2
Department of Physics and IFAE, Universitat Autònoma de Barcelona, Edifici Ciències, 08193, Bellaterra, Barcelona, Spain
3
Physik-Institut, Universität Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
4
LTP, Paul Scherrer Institut, Foruschungsstr. 101, 5232, Villigen, Aargau, Switzerland
a
bcapdevila@ifae.es
b
andreas.crivellin@psi.ch
c
matias@ifae.es
Received:
31
August
2023
Accepted:
7
November
2023
Published online:
12
December
2023
We review the current status and implications of the anomalies (i.e. deviations from the Standard Model predictions) in semi-leptonic B meson decays, both in the charged and in the neutral current. In transitions significant tensions between measurements and the Standard Model predictions exist. They are most pronounced in the branching ratios
and
(albeit quite dependent on the form factors used) as well as in angular observables in
(the
anomaly). Because the measurements of
and of the ratios R(K) and
agree reasonably well with the SM predictions, this points towards (dominantly) lepton flavour universal NP coupling vectorially to leptons, i.e. contributions to
. In fact, global fits prefer this scenario over the SM hypothesis by
. Concerning
transitions, R(D) and
suggest constructive new physics at the level of
(w.r.t. the Standard Model amplitude) with a significance above
. We discuss new physics explanations of both anomalies separately as well as possible combined explanations. In particular, a left-handed vector current solution to
, either via the
leptoquark or the combination of the scalar leptoquarks
and
, leads to an effect in
via an off-shell penguin with the right sign and magnitude and a combined significance (including a tree-level effect resulting in
and
) of
. Such a scenario can be tested with
decays. Finally, we point out an interesting possible correlation of
with non-leptonic B anomalies.
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© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.