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Lepton Flavor Universality Violation (LFUV) in $B$ decays in both neutral $b\rightarrow s l^+ l^-$ and charged $b\rightarrow cl\bar{\nu}_{l}$ processes observed in the ratios $R_{K^{(*)}}$ and $R_{D^{(*)}}$ is investigated in the framework…

High Energy Physics - Phenomenology · Physics 2022-02-16 Soumia Lebbal , Jamal Mimouni , Noureddine Mebarki

We study the generic features of minimal gauge extensions of the Standard Model in view of recent hints of lepton-flavor non-universality in semi-leptonic $b \to s \ell^+ \ell^-$ and $b \to c \ell \nu$ decays. We classify the possible…

High Energy Physics - Phenomenology · Physics 2016-07-08 Sofiane M. Boucenna , Alejandro Celis , Javier Fuentes-Martin , Avelino Vicente , Javier Virto

A number of recent experimental measurements suggest the possibility of a breakdown of lepton ($\ell$) universality in exclusive $b \to c \ell \nu_\ell$ semileptonic meson decays. We analyze the full differential decay rates for several…

High Energy Physics - Phenomenology · Physics 2018-08-29 Thomas D. Cohen , Henry Lamm , Richard F. Lebed

These proceedings review the status of New Physics contributions to flavour violating $B$ decays. The anomalies in charged and neutral current $B$ decays related to lepton flavour universality violation have received a substantial amount of…

High Energy Physics - Phenomenology · Physics 2022-09-21 Monika Blanke

We present an overview of searches fo violation of lepton flavor universality with focus on low energy precision probes using pions, kaons, tau leptons, and nuclear beta decays. The current experimental results are reviewed, the theoretical…

High Energy Physics - Phenomenology · Physics 2022-10-12 Douglas Bryman , Vincenzo Cirigliano , Andreas Crivellin , Gianluca Inguglia

We explore the possibility that lepton family numbers and baryon number are such good symmetries of Nature because they are the global remnant of a spontaneously broken gauge symmetry. An almost arbitrary linear combination of these…

High Energy Physics - Phenomenology · Physics 2020-01-15 Wolfgang Altmannshofer , Joe Davighi , Marco Nardecchia

We consider an abelian extension of the Standard Model (SM) comprising a new gauge group $U(1)^\prime$, with the neutral gauge boson $Z^\prime$ having flavour violating couplings to quarks and leptons. The fermion content is the same as in…

High Energy Physics - Phenomenology · Physics 2025-11-27 Pietro Colangelo , Fulvia De Fazio , Davide Milillo

The kaon sector is characterised by several processes which are under active investigation across different experiments. In this work, we present the global picture that emerges from a study of the different decay modes. We begin by…

High Energy Physics - Phenomenology · Physics 2022-09-27 G. D'Ambrosio , A. M. Iyer , F. Mahmoudi , S. Neshatpour

We present a global analysis of lepton-flavor-specific operators in the Standard Model Effective Field Theory (SMEFT), combining data from collider and flavor physics experiments. We systematically explore various lepton-flavor scenarios,…

High Energy Physics - Phenomenology · Physics 2025-11-11 Cornelius Grunwald , Gudrun Hiller , Kevin Kröninger , Lara Nollen

The flavor-changing neutral current semileptonic decays of $B$ mesons provide an excellent platform for indirectly probing New Physics (NP) beyond the Standard Model (SM). Recent measurements of lepton flavor universality (LFU) ratios such…

High Energy Physics - Phenomenology · Physics 2026-01-08 Md Isha Ali , Utpal Chattopadhyay , Dilip Kumar Ghosh , N Rajeev

This article reviews the current theoretical and experimental status of the field of muon decay and its potential to search for new physics beyond the Standard Model. The importance of rare muon processes with lepton flavor violation is…

High Energy Physics - Phenomenology · Physics 2008-11-26 Yoshitaka Kuno , Yasuhiro Okada

The Standard Model (SM) of particle physics represents our most fundamental knowledge of elementary particles and their interactions. One of the cardinal properties of the SM which has been thoroughly studied during the past years is the…

High Energy Physics - Experiment · Physics 2025-07-16 Sara Celani

Motivated by the recent LHCb announcement of a $3.1\sigma$ violation of lepton-flavor universality in the ratio $R_K=\Gamma(B\to K\mu^+\mu^-)/\Gamma(B\to K e^+ e^-)$, we present an updated, comprehensive analysis of the flavor anomalies…

High Energy Physics - Phenomenology · Physics 2021-09-28 Claudia Cornella , Darius A. Faroughy , Javier Fuentes-Martin , Gino Isidori , Matthias Neubert

The deviations with respect to the Standard Model (SM) that are currently observed in $b \to s \ell\ell$ transitions (the so-called flavour anomalies) can be interpreted in terms of different New Physics (NP) scenarios within a…

High Energy Physics - Phenomenology · Physics 2019-04-24 Marcel Algueró , Bernat Capdevila , Sébastien Descotes-Genon , Pere Masjuan , Joaquim Matias

The most recent measurements of the observables $R_{D^{(*)}}$ are in tension with the Standard Model offering hints of New Physics in $b\rightarrow c \ell \bar{\nu}_{\ell}$ transitions. Motivated by these results, in this work we present an…

High Energy Physics - Phenomenology · Physics 2018-12-14 Giovanni Banelli , Robert Fleischer , Ruben Jaarsma , Gilberto Tetlalmatzi-Xolocotzi

Motivated by the measurements of $b\to s\ell^+\ell^-$ transitions, including $R(K)$ and $R(K^*)$, we examine lepton flavour (universality) violation in $B$ decays and its connections to $\mu\to e\gamma$ in generic leptoquark models.…

High Energy Physics - Phenomenology · Physics 2018-02-07 Andreas Crivellin , Dario Mueller , Adrian Signer , Yannick Ulrich

Present measurements of b->c tau nu and b->u tau nu transitions differ from the standard model predictions of lepton flavor universality by almost 4sigma. We examine new physics interpretations of this anomaly. An effective field theory…

High Energy Physics - Phenomenology · Physics 2013-01-04 Svjetlana Fajfer , Jernej F. Kamenik , Ivan Nisandzic , Jure Zupan

We analyse the violations of lepton-flavour universality in the ratios B(P -> l nu)/B(P -> l' nu) using a general effective theory approach, discussing various flavour-symmetry breaking patterns of physics beyond the SM. We find that in…

High Energy Physics - Phenomenology · Physics 2009-11-05 Alberto Filipuzzi , Gino Isidori

Leptoquarks are ubiquitous in several extensions of the Standard Model and seem to be able to accommodate the universality-violation-driven $B$-meson-decay anomalies and the $(g-2)_\mu$ discrepancy interpreted as deviations from the…

High Energy Physics - Phenomenology · Physics 2022-05-18 Tomas Husek , Kevin Monsalvez-Pozo , Jorge Portoles

The evidence for Lepton Flavour Universality (LFU) violation in semileptonic $B$-decays has been rising over the past few years. Relying on generic effective field theory (EFT) results, it has been shown that models addressing the…

High Energy Physics - Phenomenology · Physics 2022-07-25 Lukas Allwicher , Nudžeim Selimović