scholarly journals Effective field theory for heavy vector resonances coupled to the Standard Model

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Mathias Heiles ◽  
Matthias König ◽  
Matthias Neubert
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Effective Theory ◽  
Effective Lagrangian ◽  
Scale Ratio ◽  
Rigorous Framework ◽  
Physics Model

Abstract We construct an effective field theory describing the decays of a heavy vector resonance V into Standard Model particles. The effective theory is built using an extension of Soft-Collinear Effective Theory called SCETBSM, which provides a rigorous framework for parameterizing decay matrix elements with manifest power counting in the ratio of the electroweak scale and the mass of the resonance, λv/mV. Using the renormalization-group evolution of the couplings in the effective Lagrangian, large logarithms associated with this scale ratio can be resummed to all orders. We consider in detail the two-body decays of a heavy Z′ boson and of a Kaluza-Klein gluon at leading and subleading order in λ. We illustrate the matching onto SCETBSM with a concrete example of a UV-complete new-physics model.

scholarly journals Long-lived heavy neutral leptons at the LHC: four-fermion single-NR operators

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Rebeca Beltrán ◽  
Giovanna Cottin ◽  
Juan Carlos Helo ◽  
Martin Hirsch ◽  
Arsenii Titov ◽  
...  
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
High Luminosity ◽  
The Past ◽  
The Standard Model ◽  
Model Independent

Abstract Interest in searches for heavy neutral leptons (HNLs) at the LHC has increased considerably in the past few years. In the minimal scenario, HNLs are produced and decay via their mixing with active neutrinos in the Standard Model (SM) spectrum. However, many SM extensions with HNLs have been discussed in the literature, which sometimes change expectations for LHC sensitivities drastically. In the NRSMEFT, one extends the SM effective field theory with operators including SM singlet fermions, which allows to study HNL phenomenology in a “model independent” way. In this paper, we study the sensitivity of ATLAS to HNLs in the NRSMEFT for four-fermion operators with a single HNL. These operators might dominate both production and decay of HNLs, and we find that new physics scales in excess of 20 TeV could be probed at the high-luminosity LHC.

scholarly journals Probing the nonunitarity of the leptonic mixing matrix at the CEPC

2016 ◽  
Vol 31 (33) ◽  
pp. 1644006 ◽  
Author(s):  
Stefan Antusch ◽  
Oliver Fischer
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Neutrino Masses ◽  
Performance Parameters ◽  
The Standard Model ◽  
Mixing Matrix ◽  
Theory Framework

The nonunitarity of the leptonic mixing matrix is a generic signal of new physics aiming at the generation of the observed neutrino masses. We discuss the Minimal Unitarity Violation (MUV) scheme, an effective field theory framework which represents the class of extensions of the Standard Model (SM) by heavy neutral leptons, and discuss the present bounds on the nonunitarity parameters as well as estimates for the sensitivity of the CEPC, based on the performance parameters from the preCDR.

scholarly journals Effective field theory interpretation of lepton magnetic and electric dipole moments

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Jason Aebischer ◽  
Wouter Dekens ◽  
Elizabeth E. Jenkins ◽  
Aneesh V. Manohar ◽  
Dipan Sengupta ◽  
...  
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Electric Dipole ◽  
Dipole Moments ◽  
Effective Field ◽  
Effective Theory ◽  
Electric Dipole Moments ◽  
Independent Analysis ◽  
The One

Abstract We perform a model-independent analysis of the magnetic and electric dipole moments of the muon and electron. We give expressions for the dipole moments in terms of operator coefficients of the low-energy effective field theory (LEFT) and the Standard Model effective field theory (SMEFT). We use one-loop renormalization group improved perturbation theory, including the one-loop matching from SMEFT onto LEFT, and one-loop lepton matrix elements of the effective-theory operators. Semileptonic four-fermion operators involving light quarks give sizable non-perturbative contributions to the dipole moments, which are included in our analysis. We find that only a very limited set of the SMEFT operators is able to generate the current deviation of the magnetic moment of the muon from its Standard Model expectation.

scholarly journals A FB in the SMEFT: precision Z physics at the LHC

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Víctor Bresó-Pla ◽  
Adam Falkowski ◽  
Martín González-Alonso
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Precision Measurements ◽  
Vertex Corrections ◽  
The Standard Model ◽  
Electroweak Precision

Abstract We study the forward-backward asymmetry AFB in pp → ℓ+ℓ− at the Z peak within the Standard Model Effective Field Theory (SMEFT). We find that this observable provides per mille level constraints on the vertex corrections of the Z boson to quarks, which close a flat direction in the electroweak precision SMEFT fit. Moreover, we show that current AFB data is precise enough so that its inclusion in the fit improves significantly LEP bounds even in simple New Physics setups. This demonstrates that the LHC can compete with and complement LEP when it comes to precision measurements of the Z boson properties.

scholarly journals General non-leptonic ∆F = 1 WET at the NLO in QCD

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Jason Aebischer ◽  
Christoph Bobeth ◽  
Andrzej J. Buras ◽  
Jacky Kumar ◽  
Mikołaj Misiak
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
High Energy ◽  
Effective Field ◽  
Effective Theory ◽  
Leading Order ◽  
The Standard Model ◽  
Complete Set ◽  
The One

Abstract We reconsider the complete set of four-quark operators in the Weak Effective Theory (WET) for non-leptonic ∆F = 1 decays that govern s → d and b → d, s transitions in the Standard Model (SM) and beyond, at the Next-to-Leading Order (NLO) in QCD. We discuss cases with different numbers Nf of active flavours, intermediate threshold corrections, as well as the issue of transformations between operator bases beyond leading order to facilitate the matching to high-energy completions or the Standard Model Effective Field Theory (SMEFT) at the electroweak scale. As a first step towards a SMEFT NLO analysis of K → ππ and non-leptonic B-meson decays, we calculate the relevant WET Wilson coefficients including two-loop contributions to their renormalization group running, and express them in terms of the Wilson coefficients in a particular operator basis for which the one-loop matching to SMEFT is already known.

scholarly journals The effective field theory of low scale see-saw at colliders

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Anke Biekötter ◽  
Mikael Chala ◽  
Michael Spannowsky
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Current Data ◽  
Missing Energy ◽  
Final State ◽  
Tau Decays ◽  
The Right

Abstract We study the Standard Model effective field theory ($$\nu $$νSMEFT) extended with operators involving right-handed neutrinos, focussing on the regime where the right-handed neutrinos decay promptly on collider scales to a photon and a Standard Model neutrino. This scenario arises naturally for right-handed neutrinos with masses of the order $$m_N \sim 0.1 \dots 10\, \,\text {GeV}$$mN∼0.1⋯10GeV. We limit the relevant dimension-six operator coefficients using LEP and LHC searches with photons and missing energy in the final state as well as pion and tau decays. While bounds on new physics contributions are generally in the TeV scale for order one operator coefficients, some coefficients, however, remain very poorly constrained or even entirely evade bounds from current data. Consequently, we identify such weakly constrained scenarios and propose new searches for rare top and tau decays involving photons to probe potential new physics in the $$\nu $$νSMEFT parameter space. Our analysis highlights the importance of performing dedicated searches for new rare tau and top decays.

scholarly journals Effective Field Theory with Nambu–Goldstone Modes

2020 ◽  
pp. 137-219 ◽  
Author(s):  
Antonio Pich
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Dynamical Symmetry ◽  
New Physics ◽  
Effective Field ◽  
Low Energy ◽  
Effective Theory ◽  
Current Status ◽  
Symmetry Properties ◽  
Effective Theories

These lectures provide an introduction to the low-energy dynamics of Nambu–Goldstone fields, which associated with some spontaneous (or dynamical) symmetry breaking, using the powerful methods of effective field theory. The generic symmetry properties of these massless modes are described in detail and two very relevant phenomenological applications are worked out: chiral perturbation theory, the low-energy effective theory of QCD, and the (non-linear) electroweak effective theory. The similarities and differences between these two effective theories are emphasized, and their current status is reviewed. Special attention is given to the short-distance dynamical information encoded in the low-energy couplings of the effective Lagrangians. The successful methods developed in QCD could help us to uncover fingerprints of new physics scales from future measurements of the electroweak effective theory couplings.

scholarly journals Beyond the Standard Model physics at CLIC

2020 ◽  
Vol 35 (15n16) ◽  
pp. 2041015 ◽  
Author(s):  
Roberto Franceschini
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Direct Search ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Open Issues

A summary of the recent results from CERN Yellow Report on the CLIC potential for new physics is presented. Greater emphasis is put on the direct search for new physics scenarios motivated by the open issues of the Standard Model as well as on interpretations of Standard Model measurements as probes of new physics in the context of effective field theory extensions of the Standard Model.

scholarly journals The Higgs di-photon decay in the standard model effective field theory

2019 ◽  
Vol 17 (1, spec.issue) ◽  
pp. 89-96
Author(s):  
Lampros Trifyllis
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Particle Physics ◽  
New Physics ◽  
Effective Field ◽  
Elementary Particle Physics ◽  
Photon Decay ◽  
Higher Dimensional ◽  
The Standard Model

Starting from the Standard Model (SM) of elementary particle physics, we assume that new physics effects can be encoded in higher-dimensional operators added in the SM Lagrangian. The resulting theory, the SM Effective Field Theory (SMEFT), is then used for high-accuracy phenomenological studies. Through this paper, the di-photon decay of the Higgs boson is used as a sample of a concrete calculation in the SMEFT framework.

scholarly journals Consequences of chirally enhanced explanations of (g − 2)μ for h → μμ and Z → μμ

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Andreas Crivellin ◽  
Martin Hoferichter
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Symmetry Breaking ◽  
Effective Field Theory ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
New Physics ◽  
Effective Field ◽  
Point Of View ◽  
New Particles

Abstract With the long-standing tension between experiment and Standard-Model (SM) prediction in the anomalous magnetic moment of the muon aμ recently reaffirmed by the Fermilab experiment, the crucial question becomes which other observables could be sensitive to the underlying physics beyond the SM to which aμ may be pointing. While from the effective field theory (EFT) point of view no direct correlations exist, this changes in specific new physics models. In particular, in the case of explanations involving heavy new particles above the electroweak (EW) scale with chiral enhancement, which are preferred to evade exclusion limits from direct searches, correlations with other observables sensitive to EW symmetry breaking are expected. Such scenarios can be classified according to the SU(2)L representations and the hypercharges of the new particles. We match the resulting class of models with heavy new scalars and fermions onto SMEFT and study the resulting correlations with h → μμ and Z → μμ decays, where, via SU(2)L symmetry, the latter process is related to Z → νν and modified W-μ-ν couplings.

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