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We interpret the recent hints for lepton flavor universality violation in rare $B$ meson decays. Based on a model-independent effective Hamiltonian approach, we determine regions of new physics parameter space that give a good description…

High Energy Physics - Phenomenology · Physics 2018-05-04 Wolfgang Altmannshofer , Peter Stangl , David M. Straub

Even though the LHC searches did not unveil the new physics particles so far, LHCb hints towards deviations from lepton flavor universality in exclusive decays based on the transition $b\to s\ell\ell$. In this proceeding, we present a new…

High Energy Physics - Phenomenology · Physics 2017-10-25 Olcyr Sumensari

A recent proposal for explaining discrepancies in angular observables in the rare decay B --> K*mu+mu- with a gauged L_mu - L_tau current carried with it the prediction of lepton flavor universality violation in related B-meson decays. This…

High Energy Physics - Phenomenology · Physics 2015-10-21 Wolfgang Altmannshofer , Itay Yavin

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

In the Standard Model (SM), the coupling of the electroweak gauge bosons to the leptons is lepton flavour universal. Tests of this property constitute sensitive probes for new physics models that violate lepton flavour universality. Recent…

High Energy Physics - Experiment · Physics 2018-07-01 Christoph Langenbruch

Normalizing the recent LHCb measurement of $\Lambda_b \to \Lambda_c \tau \bar\nu$ to the standard model (SM) prediction for the $\Lambda_b \to \Lambda_c \mu \bar\nu$ rate, instead of a LEP measurement, provides a more consistent comparison…

High Energy Physics - Phenomenology · Physics 2023-01-25 Florian U. Bernlochner , Zoltan Ligeti , Michele Papucci , Dean J. Robinson

We propose a novel method to probe the persistent hints of Lepton Flavour Universality violation observed in semileptonic $B$ decays. Relying on the specific properties of the Belle II experiment, it consists in comparing the inclusive…

High Energy Physics - Phenomenology · Physics 2021-06-30 Sébastien Descotes-Genon , Svjetlana Fajfer , Jernej F. Kamenik , Martín Novoa-Brunet

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 study of lepton flavor universality violation (LFUV) in semitauonic $b$-hadron decays has become increasingly important in light of longstanding anomalies in their measured branching fractions, and the very large datasets anticipated…

High Energy Physics - Experiment · Physics 2022-12-07 Florian U. Bernlochner , Manuel Franco Sevilla , Dean J. Robinson , Guy Wormser

We report two new measurements for tests of lepton flavor universality between electrons and muons using semileptonic $B$ decays with a data set of $189~\mathrm{fb}^{-1}$ collected at the Belle II experiment between 2019 and 2021. Firstly,…

High Energy Physics - Experiment · Physics 2023-07-20 Kazuki Kojima

This report introduces two recent measurements of semileptonic $b$-hadron decays at the LHCb experiment, including a test of Lepton Flavour Universality (LFU) using $\bar{B}^0 \to D^{(*)+} l^- \bar{\nu}_l$ decays where $l\in\{\mu,\tau\}$,…

High Energy Physics - Experiment · Physics 2024-05-16 Chen Chen

Deviation from the standard model prediction is observed in many semileptonic $B$ decays mediated via $b \to c$ charged current interactions. In particular, current experimental measurements of the ratio of branching ratio $R_D$ and…

High Energy Physics - Phenomenology · Physics 2018-06-06 Rupak Dutta , Rajeev N

Inspired by the recent hints of lepton flavor universality violation in $b\to s\ell\ell$ and $b\to c\ell\nu$ transitions, we study lepton flavor violating exclusive $\Lambda_b\to\Lambda\ell_1^+\ell_2^-$ ($\ell_1\neq \ell_2$) decay, which is…

High Energy Physics - Phenomenology · Physics 2019-12-24 Diganta Das

The Standard Model (SM) is lepton flavor universal, and the recent measurements of lepton flavor universality in $B \to (K,K^*)\ell^{+}\ell^{-}$, for $\ell = \mu, \; e$, decays now lie close to the SM predictions. However, this is not the…

High Energy Physics - Phenomenology · Physics 2026-03-13 Ishtiaq Ahmed , Saba Shafaq , M. Jamil Aslam , Saadi Ishaq

Deviation from the standard model prediction is observed in many semileptonic $B$ decays mediated via $b \to c$ charged current interactions. In particular, current experimental measurements of the ratio of branching ratio $R_D$ and…

High Energy Physics - Phenomenology · Physics 2019-08-20 Rupak Dutta , N Rajeev

Semileptonic charged current $b \to c l^- \overline{\nu}_l$ decays offer a compelling avenue to probe the limits of the Standard Model and investigate lepton flavor universality (LFU). While the SM maintains flavor universality, new physics…

High Energy Physics - Experiment · Physics 2023-05-16 Abhijit Mathad

Recent anomalies in $B$-meson decays, such as deviations in $R_{D^{(*)}}$ and $B\to K\nu{\bar\nu}$, suggest possible lepton flavor universality violation and new exotic interactions. In this work, we explore these anomalies within a…

High Energy Physics - Phenomenology · Physics 2025-06-04 Bhubanjyoti Bhattacharya , Alakabha Datta , Gaber Faisel , Shaaban Khalil , Shibasis Roy

In the Standard Model, the three charged lepton are identical copies of each other, apart from mass differences. Experimental tests of this feature in decays of semileptonic b hadrons, such as $B\rightarrow D^* \tau\ nu$, are highly…

High Energy Physics - Experiment · Physics 2017-10-03 Benedetto Gianluca Siddi

The basic features of quark and lepton mass matrices can be successfully explained by natural minima of a generic potential with dynamical Yukawa fields invariant under the $[\mathrm{SU(3)}]^5\times \mathcal{O}(3)$ flavor symmetry. If this…

High Energy Physics - Phenomenology · Physics 2017-01-18 Andreas Crivellin , Javier Fuentes-Martin , Admir Greljo , Gino Isidori

Recent measurements of $b$-hadron decays show a pattern of consistent tensions with the respective Standard Model (SM) predictions. These tensions appear both in the sector of rare flavour-changing neutral currents and in tree-level…

High Energy Physics - Experiment · Physics 2021-07-13 Johannes Albrecht , Danny van Dyk , Christoph Langenbruch