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Tests of lepton flavour universality in charged-current $B$ decays offer an excellent opportunity to test the Standard Model, and show hints of new physics in analyses performed by the LHCb, Belle and BaBar experiments. These proceedings…

High Energy Physics - Experiment · Physics 2019-07-03 Suzanne Klaver

A range of flavour physics observables show tensions with their corresponding Standard Model expectations: measurements of leptonic flavour-changing neutral current processes and ratios of semi-leptonic branching fractions involving…

High Energy Physics - Phenomenology · Physics 2018-03-28 Johannes Albrecht , Florian Bernlochner , Matthew Kenzie , Stefanie Reichert , David Straub , Alison Tully

We present a complete analysis of Lepton Flavor Universality (LFU) violations in leptonic $\tau$ decays in motivated models addressing the $B$-physics anomalies, based on the $SU(4)\times SU(3)\times SU(2)\times U(1)$ gauge group. We show…

High Energy Physics - Phenomenology · Physics 2022-01-19 Lukas Allwicher , Gino Isidori , Nudzeim Selimovic

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

Recently, the LHCb collaboration announced a preliminary result of the test of lepton flavor universality (LFU) in $B\to D^{(\ast)}$ semi-leptonic decays: $R_{D}^{\rm LHCb2022} = 0.441 \pm 0.089$ and $R_{D^{\ast}}^{\rm LHCb2022} = 0.281 \pm…

High Energy Physics - Phenomenology · Physics 2024-05-30 Syuhei Iguro , Teppei Kitahara , Ryoutaro Watanabe

We study a non-universal flavor scenario at the level of the Standard Model Effective Field Theory, according to which the matrix of Wilson coefficients $c_{uW}$ of an up-type electroweak quark dipole operator is aligned with the up-type…

High Energy Physics - Phenomenology · Physics 2024-11-26 Quentin Bonnefoy , Jonathan Kley , Di Liu , Alejo N. Rossia , Chang-Yuan Yao

Probing heavy new physics beyond the Standard Model (SM) increasingly relies on global effective field theory (EFT) likelihoods. We introduce differentiable, multi-scale EFT likelihoods that combine renormalization-group evolution,…

High Energy Physics - Phenomenology · Physics 2026-03-18 Aleks Smolkovič , Peter Stangl

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

Recent anomalies in the decays of $B$ mesons and the Higgs boson provide hints towards lepton flavor (universality) violating physics beyond the Standard Model. We observe that four-fermion operators which can explain the $B$-physics…

High Energy Physics - Phenomenology · Physics 2016-05-13 Andreas Crivellin , Giancarlo D'Ambrosio , Martin Hoferichter , Lewis C. Tunstall

We implement a systematic effective field theory approach to the benchmark process $\mu\to e \gamma$, performing automated one-loop computations including dimension 6 operators and studying their anomalous dimensions. We obtain limits on…

High Energy Physics - Phenomenology · Physics 2014-10-09 Giovanni Marco Pruna , Adrian Signer

The $R(D^{(*)})$ puzzle stands for a $\sim3\sigma$ violation of lepton flavor universality between the decay rates of $B\to D^{(*)}\tau\nu$ and $B\to D^{(*)}\ell\nu$, where $\ell=e,\mu$. If it is accounted for by new physics, there is no…

High Energy Physics - Phenomenology · Physics 2022-08-10 Shikma Bressler , Federico De Vito Halevy , Yosef Nir

Recently, several new experimental results of the test of lepton flavor universality (LFU) in $B\to D^{(\ast)}$ semi-leptonic decays were announced: the first result of $R_{D}$ from the LHCb Run 1 data, the first results of $R_{D}$ and…

High Energy Physics - Phenomenology · Physics 2024-10-11 Syuhei Iguro , Teppei Kitahara , Ryoutaro Watanabe

We present an up-to-date complete model-independent global fit to $b\to s\ell^+\ell^-$ observables that confirms patterns of New Physics able to explain the data. We include the recent LHCb measurements of $R_K$, $R_{K_S}$, $R_{K^{*+}}$,…

High Energy Physics - Phenomenology · Physics 2022-05-04 Marcel Algueró , Bernat Capdevila , Sébastien Descotes-Genon , Joaquim Matias , Martín Novoa-Brunet

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

With no direct evidence for new physics at the TeV scale, deviations from the Standard Model (SM) can be explored systematically through Effective Field Theories (EFTs) such as the Standard Model EFT (SMEFT). SMEFT extends the SM by…

High Energy Physics - Experiment · Physics 2026-02-04 Dongwon Kim

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

The Inverse Seesaw mechanism is dynamically realised within the Minimal Lepton Flavour Violation context. Lepton number, whose breaking is spontaneously realised, is generalised to a global Abelian factor of the whole flavour symmetry, that…

High Energy Physics - Phenomenology · Physics 2022-10-19 Fernando Arias-Aragón , Enrique Fernández-Martínez , Manuel González-López , Luca Merlo

We study the flavor universality of the lepton couplings with the W and Z bosons. Currently, it is constrained by the electroweak precision observables. We focus on the leptonic decay of the pion. It is shown that the decay is expected to…

High Energy Physics - Phenomenology · Physics 2014-04-18 Motoi Endo , Takahiro Yoshinaga

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

We obtain constraints on four-lepton interactions in the effective field theory with dimension-6 operators. To this end, we combine the experimental input from Z boson measurements in LEP-1, W boson mass and decays, muon and tau decays,…

High Energy Physics - Phenomenology · Physics 2016-03-23 Adam Falkowski , Kin Mimouni