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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

This Thesis presents my personal contributions to two distinct fields, namely the recent experimental anomalies in B-meson decays, and the longstanding quest for a theoretical explanation of lepton masses and mixings, under a unifying…

High Energy Physics - Phenomenology · Physics 2021-11-02 Valerio Gherardi

The measurement of lepton universality parameters $R_{K^{(*)}}$ was updated by LHCb in December 2022, which indicated that the well-known anomalies in flavor-changing neutral current (FCNC) processes of B meson decays have faded away.…

High Energy Physics - Phenomenology · Physics 2023-10-31 Qiaoyi Wen , Fanrong Xu

Lepton universality, meaning the equal coupling of the electroweak gauge bosons to the different lepton flavours, is a central property of the Standard Model (SM). Tests of lepton universality in ratios of rates of $b\to s\ell^+\ell^-$…

High Energy Physics - Experiment · Physics 2023-05-19 Christoph Langenbruch

The $B\to K^*\mu\mu$ decay exhibits deviations with respect to Standard Model expectations and the measurement of the ratio $R_K$ hints at a violation of lepton-flavour universality in $B\to K\ell\ell$ transitions. Both effects can be…

High Energy Physics - Phenomenology · Physics 2017-09-13 Bernat Capdevila , Sebastien Descotes-Genon , Joaquim Matias , Javier Virto

The LHCb experiment at the Large Hadron Collider specialises in high-precision measurements of flavour physics with hadrons containing $b$ and $c$ quarks. Lepton flavour universality tests provide an accurate and clear approach to…

High Energy Physics - Experiment · Physics 2023-05-16 Alex Seuthe

The recent updated angular analysis of the $B\to K^*\mu^+\mu^-$ decay by the LHCb collaboration is interpreted by performing a global fit to all relevant measurements probing the flavour-changing neutral current $b\to s\mu^+\mu^-$…

High Energy Physics - Phenomenology · Physics 2015-03-24 Wolfgang Altmannshofer , David M. Straub

The experimental measurements on flavour physics, in tension with Standard Model predictions, exhibit large sources of Lepton Flavour Universality violation. This note summarises an analysis of the effects of the global fits to the Wilson…

High Energy Physics - Phenomenology · Physics 2021-06-15 Jorge Alda , Jaume Guasch , Siannah Penaranda

Assuming the source of the anomalies observed recently in $b \to s$ data to be new physics, there is a priori no reason to believe that - in the effective field theory language - only one type of operator is responsible for the tensions. We…

High Energy Physics - Phenomenology · Physics 2018-11-30 A. Arbey , T. Hurth , F. Mahmoudi , S. Neshatpour

Motivated by recent experimental measurements on flavour physics, in tension with Standard Model predictions, we perform an updated analysis of New Physics violating Lepton Flavour Universality, by using the effective Lagrangian approach…

High Energy Physics - Phenomenology · Physics 2019-09-04 Jorge Alda , Jaume Guasch , Siannah Peñaranda

In the Standard Model (SM), the rare transitions where a bottom quark decays into a strange quark and a pair of light leptons exhibit a potential sensitivity to physics beyond the SM. In addition, the SM embeds Lepton Flavour Universality…

High Energy Physics - Phenomenology · Physics 2018-02-14 Bernat Capdevila , Andreas Crivellin , Sébastien Descotes-Genon , Joaquim Matias , Javier Virto

The recent measurements on $R_D$, $R_{D^*}$ and $R_{J/\psi}$ by three pioneering experiments, BaBar, Belle and LHCb, indicate that the notion of lepton flavour universality is violated in the weak charged-current processes, mediated through…

High Energy Physics - Phenomenology · Physics 2021-08-06 Aishwarya Bhatta , Atasi Ray , Rukmani Mohanta

We construct an expression for a general lepton flavour universality (LFU) ratio, $R_{X}$, in $b\to s l^+ l^-$ decays in terms of a series of hadronic quantities which can be treated as nuisance parameters. This expression allows to include…

High Energy Physics - Phenomenology · Physics 2022-06-01 Gino Isidori , Davide Lancierini , Abhijit Mathad , Patrick Owen , Nicola Serra , Rafael Silva Coutinho

The recent measurement of $R_K$ at LHCb continues to support the hint of violation of lepton flavor universality. We perform a global fit for new physics in semileptonic $b\to s$ transitions using all the relevant data with a Bayesian…

High Energy Physics - Phenomenology · Physics 2019-06-21 Dinesh Kumar , Kamila Kowalska , Enrico Maria Sessolo

The Standard Model of particle physics predicts that charged leptons have the same electroweak interaction strength. This symmetry, called lepton flavour universality, was found to hold in a wide range of particle decays. One observable…

High Energy Physics - Experiment · Physics 2021-05-17 R. D. Moise

Recent experimental data on several observables in semileptonic $B$-meson decays are found to be in tension with the corresponding Standard Model predictions. Most of these deviations are related to $b \to c$ and $b \to s$ flavour changing…

High Energy Physics - Phenomenology · Physics 2020-07-27 Aleksey V. Rusov

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

We briefly report on some particular aspects of new physics searches concerning, on the one side, the CKM paradigm and, on the other, the global fit to rare $b\to s \ell\ell$ observables including lepton flavour universality ones. We put…

High Energy Physics - Phenomenology · Physics 2017-11-13 Joaquim Matias

The persisting anomalous data in semileptonic B-decays point towards New Physics models exhibiting large sources of Lepton Flavour Universality Violation. In this work we generalise previous studies by considering frameworks which include…

High Energy Physics - Phenomenology · Physics 2018-11-14 Claudia Cornella , Ferruccio Feruglio , Paride Paradisi

Since 2013, the LHCb collaboration has reported on the measurement of several observables associated to $b \to s$ transitions, finding various deviations from their predicted values in the Standard Model. These include a set of deviations…

High Energy Physics - Phenomenology · Physics 2018-10-11 Avelino Vicente