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In recent years, experiments revealed intriguing hints for new physics (NP) in semi-leptonic $B$ decays. Both in charged current processes, involving $b \to c \tau \nu$ transitions, and in the neutral currents $b\to s\ell^+\ell^-$, a…

High Energy Physics - Phenomenology · Physics 2020-10-19 Andreas Crivellin , Dario Müller , Francesco Saturnino

We present an overview of recent work on flavour physics in the presence of a sequential fourth generation. We will discuss shortly the constraints on the new parameters and in the reminder present predictions for observables like Br(B_s ->…

High Energy Physics - Phenomenology · Physics 2010-12-07 Tillmann Heidsieck

In this review article, we highlight the impact of models incorporating flavour symmetries on charged lepton flavour violating (LFV) processes. Flavour symmetries provide a natural approach to explain the peculiar mass hierarchies and…

High Energy Physics - Phenomenology · Physics 2015-06-05 Frank F. Deppisch

We study two-site deconstructions of the $SU(2)_L$ gauge group factor of the SM. Models based on this approach can explain the hierarchies of the quark masses and CKM mixing between third and light families if these fields are localised on…

High Energy Physics - Phenomenology · Physics 2024-08-12 Bernat Capdevila , Andreas Crivellin , Javier M. Lizana , Stefan Pokorski

We discuss in detail the constraints on partial compositeness coming from flavour and CP violation in the leptonic sector. In a first part we present a formulation of partial compositeness in terms of a flavour symmetry group and a set of…

High Energy Physics - Phenomenology · Physics 2016-01-27 Ferruccio Feruglio , Paride Paradisi , Andrea Pattori

Starting from the general effective hamiltonian relevant to the $b\to s$ transitions, we derive the expressions for the full angular distributions of the $B \to K^{(\ast )} \ell_1 \ell_2$ decay modes, as well as for ${\cal B}(B_s \to…

High Energy Physics - Phenomenology · Physics 2016-09-12 Damir Becirevic , Olcyr Sumensari , Renata Zukanovich Funchal

Lepton flavour violation (LFV), and lepton flavour university violation (LFUV), are striking signatures of beyond the Standard Model (BSM) physics. Recent searches for these at the ATLAS and CMS experiments are presented, using…

High Energy Physics - Experiment · Physics 2024-05-21 Holly Pacey

We analyze lepton flavour violating transitions, leptonic magnetic dipole moments (MDMs) and electric dipole moments (EDMs) in a class of models characterized by the flavour symmetry A4 x Z3 x U(1)_{FN}, whose choice is motivated by the…

High Energy Physics - Phenomenology · Physics 2008-12-18 Ferruccio Feruglio , Claudia Hagedorn , Yin Lin , Luca Merlo

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

We define a new class of $Z'$ models with neutral flavor-changing interactions at tree level in the down-quark sector. They are related in an exact way to elements of the quark mixing matrix due to an underlying flavored $U(1)'$ gauge…

High Energy Physics - Phenomenology · Physics 2015-07-17 Alejandro Celis , Javier Fuentes-Martin , Martin Jung , Hugo Serodio

We present a comprehensive phenomenological study of a class of six vector-like lepton models with seesaw-like mass contributions and strong modifications to Higgs and lepton phenomenology. We focus on lepton flavour conserving and…

High Energy Physics - Phenomenology · Physics 2026-03-24 Gregor Daberstiel , Kilian Möhling , Dominik Stöckinger , Hyejung Stöckinger-Kim

Current experimental information on the charm meson decay observables in which the $c\to s\ell\nu_\ell$ transitions occur is well compatible with the Standard Model predictions. Recent precise lattice calculations of the $D_s$ meson decay…

High Energy Physics - Phenomenology · Physics 2015-05-13 Svjetlana Fajfer , Ivan Nisandzic , Ursa Rojec

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

We investigate whether the $2.6\sigma$ deviation from lepton flavour universality in $B^+\to K^+\ell^+\ell^-$ decays recently observed at the LHCb experiment can be explained in minimal composite Higgs models. We show that a visible…

High Energy Physics - Phenomenology · Physics 2015-08-10 Christoph Niehoff , Peter Stangl , David M. Straub

We perform a global statistical analysis of the two-Higgs-doublet model with generic sources of flavour violation using \textsf{GAMBIT}. This is particularly interesting in light of deviations from the Standard Model predictions observed in…

High Energy Physics - Phenomenology · Physics 2024-11-27 Peter Athron , Andreas Crivellin , Tomás E. Gonzalo , Syuhei Iguro , Cristian Sierra

We study flavour physics and CP violation in the context of low energy Supersymmetry with non-universal soft mass terms for sfermions. Large deviations from Standard Model predictions are allowed in B-physics, as shown in two explicit…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. Piai

We present the results of an extensive analysis of lepton flavour violating decays in the Littlest Higgs model with T-parity (LHT). As lepton flavour violation is highly suppressed in the Standard Model by small neutrino masses, the LHT…

High Energy Physics - Phenomenology · Physics 2008-11-26 Cecilia Tarantino

We study the recently found anomalies in $B$-meson decays within a scenario with a warped extra dimension where the Standard Model fermions are propagating in the bulk. The anomalies are then interpreted as the result of the exchange of…

High Energy Physics - Phenomenology · Physics 2017-09-18 Eugenio Megias , Mariano Quiros , Lindber Salas

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

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