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This note presents an analysis of lepton-flavour-violating muon decays within the framework of a low-energy effective field theory that contains higher-dimensional operators allowed by QED and QCD symmetries. The decay modes $\mu\to e…

High Energy Physics - Phenomenology · Physics 2017-05-24 A. Crivellin , S. Davidson , G. M. Pruna , A. Signer

We examine the constraints that future lepton colliders would impose on the effective field theory describing modifications of top-quark interactions beyond the standard model, through measurements of the $e^+e^-\to bW^+\:\bar bW^-$…

High Energy Physics - Phenomenology · Physics 2017-09-01 Gauthier Durieux

We discuss the tension between discrete flavour symmetries and extended scalar sectors arising from lepton flavour violation experiments. The key point is that extended scalar sectors will generically lead to flavour changing neutral…

High Energy Physics - Phenomenology · Physics 2009-11-06 Adisorn Adulpravitchai , Manfred Lindner , Alexander Merle

We discuss the possibility of using the observables deduced from the angular distribution of the $B\to D^{(\ast)} \ell\bar{\nu}$ decays to test the effects of lepton flavor universality violation (LFUV). We show that the measurement of even…

High Energy Physics - Phenomenology · Physics 2019-07-16 Damir Becirevic , Marco Fedele , Ivan Nisandzic , Andrey Tayduganov

The see-saw mechanism of neutrino mass generation, when incorporated in supersymmetric theories with supergravity mediated supersymmetry breaking, results in low-energy lepton-flavour violation arising from the soft supersymmetry breaking…

High Energy Physics - Phenomenology · Physics 2009-11-10 Bruce A. Campbell , David W. Maybury , Brandon Murakami

A powerful aspect of effective field theories is connecting scales through renormalisation group (RG) flow. The anomalous dimension matrix of the Standard Model Effective Field Theory (SMEFT) encodes clues to where to find relics of heavy…

High Energy Physics - Phenomenology · Physics 2023-03-30 Camila S. Machado , Sophie Renner , Dave Sutherland

We discuss charged lepton flavour violating processes such as mu -> e gamma in supersymmetric extensions of the Standard Model and in models with gauge-Higgs unification and a warped extra dimension. In both classes of models the processes…

High Energy Physics - Phenomenology · Physics 2015-06-17 C. Hagedorn

We study the implications of an approximate $U(2)^5$ flavor symmetry at the TeV scale, under the assumption of new physics predominantly coupled to the third-generation fermions, focusing on the breaking of the $U(2)_\ell$ subgroup…

High Energy Physics - Phenomenology · Physics 2025-11-21 Sebastiano Covone , Pol Morell , Arianna Tinari

Partial compositeness as a theory of flavor in the lepton sector is assessed. We begin presenting the first systematic analysis of neutrino mass generation in this context, and identifying the distinctive mass textures. We then update the…

High Energy Physics - Phenomenology · Physics 2021-01-05 Michele Frigerio , Marco Nardecchia , Javi Serra , Luca Vecchi

We derive new constraints on effective four-fermion neutrino non-standard interactions with both quarks and electrons. This is done through the global analysis of neutrino oscillation data and measurements of coherent elastic…

High Energy Physics - Phenomenology · Physics 2023-08-08 Pilar Coloma , M. C. Gonzalez-Garcia , Michele Maltoni , João Paulo Pinheiro , Salvador Urrea

We propose renormalizable models of new physics that can explain various anomalies observed in decays of B-mesons to electron and muon pairs. The new physics states couple to linear combinations of Standard Model fermions, yielding a…

High Energy Physics - Phenomenology · Physics 2016-07-20 Ben Gripaios , M. Nardecchia , S. A. Renner

In recent times, several hints of lepton non-universality have been observed in semileptonic $B$ meson decays, both in the charged-current ($b \to c l \bar \nu_l$) and neutral-current ($b \to s ll $) transitions. Motivated by these…

High Energy Physics - Phenomenology · Physics 2019-01-16 Atasi Ray , Suchismita Sahoo , Rukmani Mohanta

We analyse how $U(3)^5$ and $U(2)^5$ flavour symmetries act on the Standard Model Effective Field Theory, providing an organising principle to classify the large number of dimension-six operators involving fermion fields. A detailed…

High Energy Physics - Phenomenology · Physics 2025-04-23 Darius A. Faroughy , Gino Isidori , Felix Wilsch , Kei Yamamoto

We propose new mechanisms for ameliorating the constraints on the Kaluza-Klein (KK) mass scale from charged lepton flavor violation in the framework of the Standard Model (SM) fields propagating in a warped extra dimension, especially in…

High Energy Physics - Phenomenology · Physics 2010-04-21 Kaustubh Agashe

We consider the leptonic and semileptonic (SL) lepton flavour violating (LFV) decays of the charged leptons in the minimal supersymmetric standard model (MSSM). The formalism for evaluation of branching fractions for the SL LFV…

High Energy Physics - Phenomenology · Physics 2008-11-26 Takeshi Fukuyama , Amon Ilakovac , Tatsuru Kikuchi

We investigate the predictions for lepton flavour number violating processes in the context of a simple left-right symmetric theory. In this context neutrinos are Majorana fermions and their masses are generated at the quantum level through…

High Energy Physics - Phenomenology · Physics 2017-04-12 Pavel Fileviez Perez , Clara Murgui

We study constraints on the Standard Model Effective Field Theory (SMEFT) from neutrino oscillations in short-baseline reactor experiments. We calculate the survival probability of reactors antineutrinos at the leading order in the SMEFT…

High Energy Physics - Phenomenology · Physics 2019-06-26 Adam Falkowski , Martín González-Alonso , Zahra Tabrizi

We investigate the flavour structure of generic extensions of the SM where quark and lepton mass hierarchies and the suppression of flavour-changing transitions originate only by the normalization constants of the fermion kinetic terms. We…

High Energy Physics - Phenomenology · Physics 2008-11-26 Sacha Davidson , Gino Isidori , Selma Uhlig

We interpret the recent hints for lepton flavor universality violation in rare $B$ meson decays. Based on a model-independent effective Hamiltonian approach, we determine regions of new physics parameter space that give a good description…

High Energy Physics - Phenomenology · Physics 2018-05-04 Wolfgang Altmannshofer , Peter Stangl , David M. Straub

Lepton flavor violation in the $\tau\mu$ sector would be a clear sign of Beyond Standard Model physics. We employ the SMEFT framework to study the process $e^+e^-\to\tau\mu$ at the ILC and CLIC. We find that the $e^+e^-$ beam polarizations…

High Energy Physics - Phenomenology · Physics 2026-01-28 Pankaj Munbodh