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The Standard Model Effective Field Theory (SMEFT) provides a consistent framework for comparing precision measurements at the LHC to the Standard Model. The observation of statistically significant non-zero SMEFT coefficients would…

High Energy Physics - Phenomenology · Physics 2021-04-27 Sally Dawson , Samuel Homiller , Samuel D. Lane

The extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix from flavour observables can be affected by physics beyond the Standard Model (SM). We provide a general roadmap to take this into account, which we apply to the case of the…

High Energy Physics - Phenomenology · Physics 2019-06-05 Sébastien Descotes-Genon , Adam Falkowski , Marco Fedele , Martín González-Alonso , Javier Virto

Data in $B$-meson decays indicate violations of lepton flavour universality, thereby raising the question about such phenomena in the charm sector. We perform a model-independent analysis of NP contributions in (semi)-leptonic decays of…

High Energy Physics - Phenomenology · Physics 2020-03-18 Robert Fleischer , Ruben Jaarsma , Gabriël Koole

We investigate Lepton Flavor Violation (LFV) in the general extension of the Standard Model parametrized by the gauge invariant operators of dimension-6. We discuss 3-body charged lepton decays and decay of $Z$ boson to lepton pair and…

High Energy Physics - Phenomenology · Physics 2014-05-20 Saereh Najjari

We study lepton flavour universality violation in SM boson decays in low-scale seesaw models of neutrino mass generation, also addressing other electroweak precision observables. We compute the electroweak next-to-leading order corrections,…

High Energy Physics - Phenomenology · Physics 2023-07-07 A. Abada , J. Kriewald , E. Pinsard , S. Rosauro-Alcaraz , A. M. Teixeira

New physics not far above the TeV scale should leave a pattern of virtual effects in observables at lower energies. What do these effects tell us about the flavor structure of a UV theory? Within the framework of Standard Model Effective…

High Energy Physics - Phenomenology · Physics 2021-06-16 Sebastian Bruggisser , Ruth Schäfer , Danny van Dyk , Susanne Westhoff

We constrain the flavor structure of Wilson coefficients in the Standard Model Effective Field Theory (SMEFT) from data. In the SMEFT, new physics effects in couplings of up-type and down-type quarks are related through the…

High Energy Physics - Phenomenology · Physics 2023-03-22 Sebastian Bruggisser , Danny van Dyk , Susanne Westhoff

Partial compositeness is a key ingredient of models where the electroweak symmetry is broken by a composite Higgs state. Recently, a UV completion of partial compositeness was proposed, featuring a new strongly coupled gauge interaction as…

High Energy Physics - Phenomenology · Physics 2018-07-04 Francesco Sannino , Peter Stangl , David M. Straub , Anders Eller Thomsen

We quantify the ability of B-Factories to observe supersymmetric contributions to the rare decays B -> X_s \gamma and B -> X_s l+ l-. A global fit to the Wilson coefficients which contribute to these decays is performed from Monte Carlo…

High Energy Physics - Phenomenology · Physics 2009-10-28 JoAnne L. Hewett , James D. Wells

The concept of lepton flavour universality (LFU), according to which the three lepton families are equivalent except for their masses, is a cornerstone prediction of the Standard Model (SM). LFU can be violated in models beyond the SM by…

High Energy Physics - Experiment · Physics 2019-05-22 Elena Graverini

We estimate the sensitivity of Wilson coefficients of the lepton flavor-violating dimension-six operators at the proposed $\mu^+\mu^-$ collider. We compute the signal significance at $\sqrt{s}$ = 3 and 10 TeV, respectively, with an…

High Energy Physics - Phenomenology · Physics 2025-01-28 Sukanta Dutta , Purnath Unnikrishnan , Yashasvi

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 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

Extending the Standard Model with higher-dimensional operators in an effective-field-theory (EFT) approach provides a systematic framework to study new-physics (NP) effects from a bottom-up perspective, as long as the NP scale is…

High Energy Physics - Phenomenology · Physics 2020-01-29 Marzia Bordone , Oscar Catà , Thorsten Feldmann

The electroweak sector of the Standard Model contains three generations of charged leptons $\ell^-\in\{e^-,\mu^-,\tau^-\}$ as exact replicas of each other, except for their Yukawa couplings to the Higgs that determine their masses. The…

High Energy Physics - Experiment · Physics 2018-12-04 Biplab Dey

Several measurements of B-meson decay observables show deviations from Standard Model (SM) predictions, some of them hinting at violation of lepton flavour universality (LFU). I discusses how the anomalies in rare B decays can be explained…

High Energy Physics - Phenomenology · Physics 2019-07-12 Peter Stangl

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 search for flavour-changing neutral current effects in $B$-meson decays is a powerful probe of physics beyond the Standard Model. Deviations from SM behaviour are often quantified by extracting the preferred values of the Wilson…

High Energy Physics - Phenomenology · Physics 2022-05-19 J. Bhom , M. Chrzaszcz , F. Mahmoudi , M. T. Prim , P. Scott , M. White

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

We present an analysis on flavour anomalies in semileptonic rare $B$-meson decays using an effective field theory approach and assuming that new physics affects only one generation in the interaction basis and non-universal mixing effects…

High Energy Physics - Phenomenology · Physics 2026-03-09 Jorge Alda , Alejandro Mir , Siannah Penaranda