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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

We analyse the new physics implications of theoretically clean $b \to s$ observables in a model-independent approach and compare their coherence with the implications of other rare $B$-decays. A statistical comparison is done between the…

High Energy Physics - Phenomenology · Physics 2021-12-16 T. Hurth , F. Mahmoudi , D. Martinez Santos , S. Neshatpour

The LHCb experiment has made several measurements in $b \to s$ transitions which indicate tensions with the Standard Model predictions. Assuming the source of these tensions to be new physics, we present new global fits to all Wilson…

High Energy Physics - Phenomenology · Physics 2018-12-20 T. Hurth , A. Arbey , F. Mahmoudi , S. Neshatpour

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

The LHCb measurements of certain ratios of decay modes testing lepton flavour non-universality might open an exciting world of new physics beyond the standard model. The latest LHCb measurements of R_K* offer some new insight beyond the…

High Energy Physics - Phenomenology · Physics 2017-11-29 T. Hurth , F. Mahmoudi , D. Martinez Santos , S. Neshatpour

Within the standard approach of effective field theory of weak interactions for $\Delta B = 1$ transitions, we look for possibly unexpected subtle New Physics effects, here dubbed "flavourful Easter eggs". We perform a Bayesian global fit…

High Energy Physics - Phenomenology · Physics 2017-10-04 Marco Ciuchini , Antonio M. Coutinho , Marco Fedele , Enrico Franco , Ayan Paul , Luca Silvestrini , Mauro Valli

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

We perform a model-independent global fit to $b\to s\ell^+\ell^-$ observables to confirm existing New Physics (NP) patterns (or scenarios) and to identify new ones emerging from the inclusion of the updated LHCb and Belle measurements of…

Following the updated measurement of the lepton flavour universality (LFU) ratio R_K in B -> Kll decays by LHCb, as well as a number of further measurements, e.g. R_K* by Belle and B_s -> mu mu by ATLAS, we analyse the global status of new…

High Energy Physics - Phenomenology · Physics 2020-04-22 Jason Aebischer , Wolfgang Altmannshofer , Diego Guadagnoli , Meril Reboud , Peter Stangl , David M. Straub

We critically analyze the body of results that hints to the existence of New Physics from possible violations of lepton universality observed by the LHCb experiment in the $\mu/e$ ratios $R_{K}$ and $R_{K^*}$ to the $g-2$ lepton anomalies.…

Several experimental measurements of $B$ meson decays, in tension with Standard Model predictions, exhibit large sources of Lepton Flavour Universality violation. We perform an analysis of the effects of the global fits to the Wilson…

High Energy Physics - Phenomenology · Physics 2021-10-26 Jorge Alda , Jaume Guasch , Siannah Penaranda

Tests of lepton-universality as rate ratios in $b\to s \ell\ell$ transitions can be predicted very accurately in the Standard Model. The deficits with respect to expectations reported by the LHCb experiment in muon-to-electron ratios of the…

High Energy Physics - Phenomenology · Physics 2020-02-03 Li-Sheng Geng , Benjamín Grinstein , Sebastian Jäger , Jorge Martin Camalich , Xiu-Lei Ren , Rui-Xiang Shi

In recent years, intriguing hints for the violation of Lepton Flavour Universality (LFU) have been accumulated in semileptonic $B$ decays, both in the neutral-current transitions $b\to s\ell^+\ell^-$ (i.e., $R_K$ and $R_{K^*}$) and the…

High Energy Physics - Phenomenology · Physics 2018-05-09 Bernat Capdevila , Andreas Crivellin , Sébastien Descotes-Genon , Lars Hofer , Joaquim Matias

Recently the LHCb collaboration has confirmed the evidence for lepton flavour nonuniversality at the $3.1\sigma$ level via an updated measurement of $R_K$. In this work we analyse this evidence within a model-independent approach. We make…

High Energy Physics - Phenomenology · Physics 2021-12-15 T. Hurth , F. Mahmoudi , D. Martinez Santos , S. Neshatpour

The Standard Model predicts that the electroweak couplings to the three charged leptons are identical. However, in the last decade, experimental measurements have suggested that semileptonic processes involving taus could have a slightly…

High Energy Physics - Experiment · Physics 2024-10-24 Rizwaan Mohammed

Rare semileptonic $b \to s \ell^+ \ell^-$ transitions provide some of the most promising frameworks to search for new physics effects. Recent analyses of these decays have indicated an anomalous behaviour in measurements of angular…

High Energy Physics - Phenomenology · Physics 2019-03-21 Andrea Mauri , Nicola Serra , Rafael Silva Coutinho

Intriguing results for tests of the universality of electrons and muons through measurements of rates of $B\to K \ell^+ \ell^-$ and similar decays have been in the spotlight for years. The LHCb collaboration has recently reported new…

High Energy Physics - Phenomenology · Physics 2023-06-21 Robert Fleischer , Eleftheria Malami , Anders Rehult , K. Keri Vos

In light of the very recent updates on the $R_K$ and $R_{K^*}$ measurements from the LHCb and Belle collaborations, we systematically explore here imprints of New Physics in $b \to s \ell^+ \ell^- $ transitions using the language of…

High Energy Physics - Phenomenology · Physics 2019-09-17 Marco Ciuchini , António M. Coutinho , Marco Fedele , Enrico Franco , Ayan Paul , Luca Silvestrini , Mauro Valli

We present results of global fits of all relevant experimental data on rare $b \to s$ decays. We observe significant tensions between the Standard Model predictions and the data. After critically reviewing the possible sources of…

High Energy Physics - Phenomenology · Physics 2015-09-30 Wolfgang Altmannshofer , David M. Straub

We investigate new-physics contributions to $b\to s \ell\ell$ transitions in the context of an effective field theory extension of the Standard Model, including operator mixing at one loop. We identify the few scenarios where a single…

High Energy Physics - Phenomenology · Physics 2020-02-19 Rupert Coy , Michele Frigerio , Federico Mescia , Olcyr Sumensari
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