# Are we overlooking lepton-flavor-universal new physics in $b\to s\ell \ell$ ?

Algueró, Marcel (Grup de Física Teòrica (Departament de Física), Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain) (Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, E-08193 Bellaterra (Barcelona), Spain) ; Capdevila, Bernat (Grup de Física Teòrica (Departament de Física), Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain) (Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, E-08193 Bellaterra (Barcelona), Spain) ; Descotes-Genon, Sébastien (Laboratoire de Physique Théorique, UMR 8627, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France) ; Masjuan, Pere (Grup de Física Teòrica (Departament de Física), Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain) (Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, E-08193 Bellaterra (Barcelona), Spain) ; Matias, Joaquim (Grup de Física Teòrica (Departament de Física), Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain) (Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, E-08193 Bellaterra (Barcelona), Spain)

15 April 2019

Abstract: The deviations with respect to the Standard Model that are currently observed in $b\to s\ell \ell$ transitions (the so-called flavor anomalies) can be interpreted in terms of different new physics (NP) scenarios within a model-independent effective approach. We reconsider the determination of NP in global fits from a different perspective by removing one implicit hypothesis of current analyses, namely, that NP is only lepton-flavor-universality violating (LFUV). We examine the roles played by LFUV NP and lepton-flavor-universal NP altogether, providing new directions to identify the possible theory beyond the SM responsible for the anomalies observed. New patterns of NP emerge due to the possibility of allowing at the same time large LFUV and lepton-flavor-universal NP contributions to ${C}_{10\mu }$, which provides a different mechanism to obey the constraint from the ${B}_{s}\to {\mu }^{+}{\mu }^{-}$ branching ratio. In this landscape of NP, we discuss how to discriminate among these scenarios in the short term, thanks to current and forthcoming observables. While the update of ${R}_{K}$ will be a major milestone to confirm the NP origin of the flavor anomalies, additional observables, in particular the LFUV angular observable ${Q}_{5}$, turn out to be central to assessing the precise NP scenario responsible for the observed anomalies.

Published in: Physical Review D 99 (2019)