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The Standard Model Effective Field Theory (SMEFT) provides a systematic framework to probe indirect effects of heavy new physics via precision measurements. While SMEFT constraints have been extensively studied using purely leptonic $Z$…

High Energy Physics - Phenomenology · Physics 2026-05-13 Zijian Wang , Tianyi Yang , Tianyu Mu , Andrew Levin , Qiang Li

We perform a global analysis of the bounds from charged lepton flavour violating observables to new physics. We parametrize generic new physics through the Effective Field Theory formalism and perform global fits beyond the common…

High Energy Physics - Phenomenology · Physics 2025-10-07 Enrique Fernández-Martínez , Xabier Marcano , Daniel Naredo-Tuero

We analyze lepton flavor violation (LFV) using the Standard Model Effective Field Theory (SMEFT) framework at the future lepton colliders. Our focus is on the associated production of tau lepton with electron/muon at the electron-positron…

High Energy Physics - Phenomenology · Physics 2025-05-28 Sahabub Jahedi , Abhik Sarkar

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

Recently the CDF collaboration at the Tevatron reported a significant discrepancy between the direct measurement of the $W$-boson mass and its Standard Model (SM) prediction based on electroweak precision tests (EWPTs). In this paper we…

High Energy Physics - Phenomenology · Physics 2022-11-09 JiJi Fan , Lingfeng Li , Tao Liu , Kun-Feng Lyu

In this paper we present a detailed analysis of the Electroweak Precision Observables (EWPO) in composite Higgs models based on the coset $SO(5)/SO(4)$. In our study we include both the fermionic top partners and the spin-1 resonances and…

High Energy Physics - Phenomenology · Physics 2016-12-01 Diptimoy Ghosh , Matteo Salvarezza , Fabrizio Senia

We present comprehensive global fits of the SMEFT under the $\textit{minimal}$ minimal flavour violation (MFV) hypothesis, i.e. assuming that only the flavour-symmetric and CP-invariant operators are relevant at the high scale. The…

High Energy Physics - Phenomenology · Physics 2023-12-07 Riccardo Bartocci , Anke Biekötter , Tobias Hurth

In the absence of direct evidence of new physics, any ultraviolet theory can be reduced to its specific set of low-energy effective operators. As a case study, we derive the effective field theory for the seesaw extension of the Standard…

High Energy Physics - Phenomenology · Physics 2021-10-19 Rupert Coy , Michele Frigerio

We implement electroweak renormalisation schemes involving the effective weak mixing angle to NLO in Standard Model Effective Field Theory (SMEFT). After developing the necessary theoretical machinery, we analyse a select set of electroweak…

High Energy Physics - Phenomenology · Physics 2023-12-15 Anke Biekötter , Benjamin D. Pecjak , Tommy Smith

This paper presents a computer code for analyzing electroweak precision data (EWPD) in the framework of the Standard Model Effective Field Theory (SMEFT), highlights the importance of recent ATLAS and CMS precision measurements, and…

High Energy Physics - Phenomenology · Physics 2026-05-14 Hannes Mildner

We investigate the electroweak precision constraints on the recently proposed Lee-Wick Standard Model at tree level. We analyze low energy, Z-pole (LEP1/SLC) and LEP2 data separately. We derive the exact tree level low energy and Z-pole…

High Energy Physics - Phenomenology · Physics 2009-03-12 Thomas E. J. Underwood , Roman Zwicky

We investigate the information that can be gained by including flavour data in fits of the Standard Model Effective Field Theory (SMEFT) with the assumption of Minimal Flavour Violation (MFV), allowing - as initial conditions at the high…

High Energy Physics - Phenomenology · Physics 2021-01-05 Rafael Aoude , Tobias Hurth , Sophie Renner , William Shepherd

If the dynamics behind EWSB are of strongly-coupled nature, the Standard Model ceases to be renormalizable and should be instead understood as an effective field theory (EFT). Here I will discuss the systematics behind this effective field…

High Energy Physics - Phenomenology · Physics 2013-05-24 Oscar Cata

We analyze new physics contributions to $e^+e^-\to W^+W^-$ at the TeV energy scale, employing an effective field theory framework. A complete basis of next-to-leading order operators in the standard model effective Lagrangian is used, both…

High Energy Physics - Phenomenology · Physics 2015-06-15 G. Buchalla , O. Cata , R. Rahn , M. Schlaffer

We present a global likelihood function in the space of dimension-six Wilson coefficients in the Standard Model Effective Field Theory (SMEFT). The likelihood includes contributions from flavour-changing neutral current B decays, lepton…

High Energy Physics - Phenomenology · Physics 2019-07-24 Jason Aebischer , Jacky Kumar , Peter Stangl , David M. Straub

Four-fermion processes with a particle lost in the beam pipe are studied at LEP to perform precision tests of the electroweak theory. Leading higher-order QED corrections to such processes are analyzed within the framework of the Structure…

High Energy Physics - Phenomenology · Physics 2009-01-07 G. Montagna , M. Moretti , O. Nicrosini , A. Pallavicini , F. Piccinini

The effective field theory (EFT) framework is a precise approximation procedure when the inherent assumptions of a large-scale separation between the Standard Model (SM) and new interactions alongside perturbativity are realised.…

High Energy Physics - Phenomenology · Physics 2024-03-22 Upalaparna Banerjee , Joydeep Chakrabortty , Christoph Englert , Wrishik Naskar , Shakeel Ur Rahaman , Michael Spannowsky

Effective field theory (EFT) approaches are widely used at the LHC, such that it is important to study their validity, and ease of matching to specific new physics models. In this paper, we consider an extension of the SM in which a top…

High Energy Physics - Phenomenology · Physics 2020-03-04 Christoph Englert , Peter Galler , Chris D. White

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

In particle physics, the modern view is to categorize things in terms of effective field theories (EFTs). Above the weak scale, we have the SMEFT, formed when the heavy new physics (NP) is integrated out, and for which the Standard Model…

High Energy Physics - Phenomenology · Physics 2023-04-05 Serge Hamoudou , Jacky Kumar , David London