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The electroweak symmetry-breaking sector is one of the most promising and uncharted parts of the Standard Model; but it seems likely that new electroweak physics may be out of reach of the present accelerator effort and the hope is to…

High Energy Physics - Phenomenology · Physics 2023-09-13 Raquel Gomez-Ambrosio , Felipe J. Llanes-Estrada , Alexandre Salas-Bernardez , Juan J. Sanz-Cillero

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

In this work, we investigate three typical new physics resonances which couple to the standard model (SM) quarks via direct top-quark flavor-changing interactions. We identify the possible SMEFT operators electroweak scale and analyze their…

High Energy Physics - Phenomenology · Physics 2026-04-16 Min Huang , Yandong Liu , Hao Zhang

Building upon the fundamental partial compositeness framework we provide consistent and complete composite extensions of the standard model. These are used to determine the effective operators emerging at the electroweak scale in terms of…

High Energy Physics - Phenomenology · Physics 2018-07-11 Giacomo Cacciapaglia , Helene Gertov , Francesco Sannino , Anders Eller Thomsen

We discuss the phenomenology of effective field theories with new scalar or vector representations of the Standard Model quark flavor symmetry group, allowing for large flavor breaking involving the third generation. Such field content can…

High Energy Physics - Phenomenology · Physics 2015-05-30 Benjamin Grinstein , Alexander L. Kagan , Michael Trott , Jure Zupan

Motivated by additional experimental hints of Lepton Flavour Universality violation in B decays, both in charged- and in neutral-current processes, we analyse the ingredients necessary to provide a combined description of these phenomena.…

High Energy Physics - Phenomenology · Physics 2017-12-06 Dario Buttazzo , Admir Greljo , Gino Isidori , David Marzocca

Effective field theory tools are essential for exploring non-Standard Model physics at the LHC in the absence of the discovery of new light particles. Predictions for observables are typically made at the lowest order in the QCD and…

High Energy Physics - Phenomenology · Physics 2024-12-19 Luigi Bellafronte , Sally Dawson , Pier Paolo Giardino

The quark sector of the Standard Model exhibits an approximate U(2)^3 flavour symmetry. This symmetry, broken in specific directions dictated by minimality, can explain the success of the Cabibbo-Kobayashi-Maskawa picture of flavour mixing…

High Energy Physics - Phenomenology · Physics 2017-08-23 Riccardo Barbieri , Dario Buttazzo , Filippo Sala , David M. Straub

Charged lepton flavour-violating (cLFV) processes, which are definite proof of new physics beyond the Standard Model, have remained elusive experimentally till now. Effective Field Theory (EFT) has been very useful in providing information…

High Energy Physics - Phenomenology · Physics 2026-01-06 Utpal Chattopadhyay , Debottam Das , Rahul Puri , Joydeep Roy

We present projections for the sensitivity of future high-energy colliders to new physics through precision measurements of the Standard Model (SM) interactions, focusing on near-term electron-positron facilities: FCC-ee, LEP3, and the…

The Standard Model Effective Field Theory (SMEFT) based on the unbroken gauge group $\text{SU(3)}_C\otimes\text{SU(2)}_L\otimes\text{U(1)}_Y$ and containing only particles of the Standard Model (SM) has developed in the last decade to a…

High Energy Physics - Phenomenology · Physics 2025-11-13 Jason Aebischer , Andrzej J. Buras , Jacky Kumar

We list all possible dimension-six CP-conserving $SU_c(3)\times SU_L(2) \times U_Y(1)$ invariant operators involving the third-family quarks which could be generated by new physics at a higher scale. Expressions for these operators after…

High Energy Physics - Phenomenology · Physics 2009-07-09 K. Whisnant , Jin Min Yang , Bing-Lin Young , X. Zhang

The ongoing Effective Field Theory (EFT) program at the LHC and elsewhere is motivated by streamlining the connection between experimental data and UV-complete scenarios of heavy new physics beyond the Standard Model (BSM). This connection…

High Energy Physics - Phenomenology · Physics 2024-05-24 Jaco ter Hoeve , Giacomo Magni , Juan Rojo , Alejo N. Rossia , Eleni Vryonidou

Electroweak precision observables (EWPO) measured at the W and Z poles provide stringent limits on possible beyond the Standard Model physics scenarios. In an effective field theory (EFT) framework, the next-to-leading order QCD and…

High Energy Physics - Phenomenology · Physics 2022-05-04 Sally Dawson , Pier Paolo Giardino

Motivated by the recent strong experimental evidence of large \nu_mu-\nu_tau neutrino mixing, we explore current bounds on the analogous mixing in the charged lepton sector. We present a general formalism for dimension-6 fermionic effective…

High Energy Physics - Phenomenology · Physics 2008-11-26 Deirdre Black , Tao Han , Hong-Jian He , Marc Sher

We study an effective theory of flavour in which the $SU(2)_L$ interaction is `flavour-deconstructed' near the TeV scale. This arises, for example, in UV models that unify all three generations of left-handed fermions via an $Sp(6)_L$…

High Energy Physics - Phenomenology · Physics 2024-04-12 Joe Davighi , Alastair Gosnay , David J Miller , Sophie Renner

We study four top quark production at hadron colliders in the Standard Model Effective Field Theory (SMEFT). We perform an analysis at the tree-level, including all possible QCD- and EW-coupling orders and relevant dimension-six operators.…

High Energy Physics - Phenomenology · Physics 2022-11-09 Rafael Aoude , Hesham El Faham , Fabio Maltoni , Eleni Vryonidou

We obtain SMEFT bounds using an approach that utilises the complete multi-dimensional differential information of a process. This approach is based on the fact that at a given EFT order, the full angular distribution in the most important…

High Energy Physics - Phenomenology · Physics 2020-11-12 Shankha Banerjee , Rick S. Gupta , Joey Y. Reiness , Satyajit Seth , Michael Spannowsky

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

Electroweak precision data constraints on flavor symmetric vector fields are determined. The flavor multiplets of spin one that we examine are the complete set of fields that couple to quark bi-linears at tree level while not initially…

High Energy Physics - Phenomenology · Physics 2012-01-12 Benjamín Grinstein , Christopher W. Murphy , Michael Trott