Header

UZH-Logo

Maintenance Infos

Review of semileptonic B anomalies


Capdevila, Bernat; Crivellin, Andreas; Matias, Joaquim (2024). Review of semileptonic B anomalies. European Physical Journal. Special Topics, 233(2):409-428.

Abstract

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 b → sl+l− transitions significant tensions between measurements and the Standard Model predictions exist. They are most pronounced in the branching ratios BB→Kμ+μ− and BBs→φμ+μ− (albeit quite dependent on the form factors used) as well as in angular observables in B → K∗μ+μ− (the P ′ 5 anomaly). Because the measurements of BBs→μ+μ− and of the ratios R(K ) and R(K∗) agree reasonably well with the SM predictions, this points towards (dominantly) lepton flavour universal NP coupling vectorially to leptons,i.e. contributions to CU9 . In fact, global fits prefer this scenario over the SM hypothesis by 5.8σ. Concerning b → cτ ν transitions, R(D) and R(D∗) suggest constructive new physics at the level of 10% (w.r.t. the Standard Model amplitude) with a significance above 3σ. We discuss new physics explanations of both anomalies separately as well as possible combined explanations. In particular, a left-handed vector current solution to R(D(∗)), either via the U1 leptoquark or the combination of the scalar leptoquarks S1 and S3, leads to an effect in CU9 via an off-shell penguin with the right sign and magnitude and a combined significance (including a tree-level effect resulting in Cμ9 = −Cμ10 and R(D(∗))) of 6.3σ. Such a scenario can be tested with b → sτ +τ − decays. Finally, we point out an interesting possible correlation of R(D(∗)) with non-leptonic B anomalies

Abstract

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 b → sl+l− transitions significant tensions between measurements and the Standard Model predictions exist. They are most pronounced in the branching ratios BB→Kμ+μ− and BBs→φμ+μ− (albeit quite dependent on the form factors used) as well as in angular observables in B → K∗μ+μ− (the P ′ 5 anomaly). Because the measurements of BBs→μ+μ− and of the ratios R(K ) and R(K∗) agree reasonably well with the SM predictions, this points towards (dominantly) lepton flavour universal NP coupling vectorially to leptons,i.e. contributions to CU9 . In fact, global fits prefer this scenario over the SM hypothesis by 5.8σ. Concerning b → cτ ν transitions, R(D) and R(D∗) suggest constructive new physics at the level of 10% (w.r.t. the Standard Model amplitude) with a significance above 3σ. We discuss new physics explanations of both anomalies separately as well as possible combined explanations. In particular, a left-handed vector current solution to R(D(∗)), either via the U1 leptoquark or the combination of the scalar leptoquarks S1 and S3, leads to an effect in CU9 via an off-shell penguin with the right sign and magnitude and a combined significance (including a tree-level effect resulting in Cμ9 = −Cμ10 and R(D(∗))) of 6.3σ. Such a scenario can be tested with b → sτ +τ − decays. Finally, we point out an interesting possible correlation of R(D(∗)) with non-leptonic B anomalies

Statistics

Citations

Dimensions.ai Metrics
1 citation in Web of Science®
4 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

0 downloads since deposited on 05 Jan 2024
0 downloads since 12 months

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Scopus Subject Areas:Physical Sciences > General Materials Science
Physical Sciences > General Physics and Astronomy
Physical Sciences > Physical and Theoretical Chemistry
Uncontrolled Keywords:Physical and Theoretical Chemistry, General Physics and Astronomy, General Materials Science
Language:English
Date:1 April 2024
Deposited On:05 Jan 2024 12:25
Last Modified:30 Jun 2024 01:36
Publisher:Springer
ISSN:1951-6355
OA Status:Closed
Publisher DOI:https://doi.org/10.1140/epjs/s11734-023-01012-2