scholarly journals The anomalous case of axion EFTs and massive chiral gauge fields

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Quentin Bonnefoy ◽  
Luca Di Luzio ◽  
Christophe Grojean ◽  
Ayan Paul ◽  
Alejo N. Rossia
Keyword(s):  
Sum Rules ◽  
Higgs Sector ◽  
Effective Field ◽  
Gauge Fields ◽  
Gauge Bosons ◽  
The Standard Model ◽  
Electroweak Sector ◽  
Complete Theories ◽  
Electroweak Precision ◽  
Extended Higgs Sector

Abstract We study axion effective field theories (EFTs), with a focus on axion couplings to massive chiral gauge fields. We investigate the EFT interactions that participate in processes with an axion and two gauge bosons, and we show that, when massive chiral gauge fields are present, such interactions do not entirely originate from the usual anomalous EFT terms. We illustrate this both at the EFT level and by matching to UV-complete theories. In order to assess the consistency of the Peccei-Quinn (PQ) anomaly matching, it is useful to introduce an auxiliary, non-dynamical gauge field associated to the PQ symmetry. When applied to the case of the Standard Model (SM) electroweak sector, our results imply that anomaly-based sum rules between EFT interactions are violated when chiral matter is integrated out, which constitutes a smoking gun of the latter. As an illustration, we study a UV-complete chiral extension of the SM, containing an axion arising from an extended Higgs sector and heavy fermionic matter that obtains most of its mass by coupling to the Higgs doublets. We assess the viability of such a SM extension through electroweak precision tests, bounds on Higgs rates and direct searches for heavy charged matter. At energies below the mass of the new chiral fermions, the model matches onto an EFT where the electroweak gauge symmetry is non-linearly realised.

scholarly journals Constraining the gauge and scalar sectors of the doublet left-right symmetric model

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Véronique Bernard ◽  
Sébastien Descotes-Genon ◽  
Luiz Vale Silva
Keyword(s):  
Symmetry Breaking ◽  
Electroweak Symmetry Breaking ◽  
Symmetric Model ◽  
Electroweak Symmetry ◽  
Gauge Bosons ◽  
Spontaneous Breakdown ◽  
The Standard Model ◽  
Low Energies ◽  
Precision Observables ◽  
Electroweak Precision

Abstract We consider a left-right symmetric extension of the Standard Model where the spontaneous breakdown of the left-right symmetry is triggered by doublets. The electroweak ρ parameter is protected from large corrections in this Doublet Left-Right Model (DLRM), contrary to the triplet case. This allows in principle for more diverse patterns of symmetry breaking. We consider several constraints on the gauge and scalar sectors of DLRM: the unitarity of scattering processes involving gauge bosons with longitudinal polarisations, the radiative corrections to the muon ∆r parameter and the electroweak precision observables measured at the Z pole and at low energies. Combining these constraints within the frequentist CKMfitter approach, we see that the fit pushes the scale of left-right symmetry breaking up to a few TeV, while favouring an electroweak symmetry breaking triggered not only by the SU(2)L×SU(2)R bi-doublet, which is the case most commonly considered in the literature, but also by the SU(2)L doublet.

HIGGS BOSONS

1990 ◽  
Vol 05 (26) ◽  
pp. 2087-2100 ◽  
Author(s):  
A. MÉNDEZ
Keyword(s):  
Standard Model ◽  
Higgs Sector ◽  
Higgs Bosons ◽  
Supersymmetric Model ◽  
The Standard Model ◽  
Doublet Model ◽  
Minimal Supersymmetric Model ◽  
Extended Higgs Sector

The main phenomenological aspects of the Higgs bosons are briefly reviewed in the context of the Standard Model and in models with an "extended" Higgs sector. Among the latter, special emphasis is made on the Two-Doublet Model and, particularly, the Minimal Supersymmetric Model.

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 Leptonic g − 2 anomaly in an extended Higgs sector with vector-like leptons

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Hrishabh Bharadwaj ◽  
Sukanta Dutta ◽  
Ashok Goyal
Keyword(s):  
Parameter Space ◽  
Dipole Moments ◽  
Higgs Sector ◽  
Higgs Doublet ◽  
Gauge Bosons ◽  
Complex Scalar ◽  
Complex Scalar Field ◽  
Doublet Model ◽  
Two Higgs Doublet Model ◽  
Extended Higgs Sector

Abstract We address the observed discrepancies in the anomalous magnetic dipole moments (MDM) of the muon and electron by extending the inert two Higgs Doublet Model (2HDM) with SM gauge singlet complex scalar field and singlet Vector-like Lepton (VLL) field. We obtain the allowed parameter space constrained from the Higgs decays to gauge Bosons at LHC, LEP II data and electro-weak precision measurements. The muon and electron MDM’s are then explained within a common parameter space for different sets of allowed couplings and masses of the model particles.

scholarly journals On the D*s and charmonia leptonic decays

2018 ◽  
Vol 175 ◽  
pp. 13002
Author(s):  
Gabriela Bailas ◽  
Benoît Blossier ◽  
Jochen Heitger ◽  
Vincent Morénas ◽  
Matthias Post
Keyword(s):  
Large Range ◽  
Chiral Limit ◽  
Higgs Sector ◽  
New Physics ◽  
Decay Constants ◽  
Leptonic Decays ◽  
The Standard Model ◽  
Extended Higgs Sector ◽  
Flavour Physics

Among the different scenarios of New Physics, those with an extended Higgs sector are examined with a lot of attention. Recent experimental observations of several anomalies in flavour physics with respect to expectations of the Standard Model further motivate the effort of phenomenologists. First, informations about the RDs ratio, a test of lepton flavour universality equivalent to RD, already measured, but with the s quark as spectator, are awaited in coming years to constrain the corner of an extended Higgs sector with charged doublets. On another side, leptonic widths of pseudoscalar quarkonia are particularly interesting to test an extended Higgs sector with a light CP-odd Higgs boson singlet, through the study of its mixing with quarkonia states. Hadronic parameters entering those processes have to be determined from lattice QCD with enough confidence on the control of systematic errors. We report on the very first step of a long-term program tackled with Nf = 2 Wilson-Clover fermions to put relevant constraints on extensions of the Higgs sector: extraction of decay constants of D*s, ƞc, ƞc (2S), J/Ψ and Ψ(2S) with lattice ensembles provided by the CLS effort, considering 2 lattice spacings and a large range of pion masses to estimate cut-off effects and extrapolate results to the chiral limit.

scholarly journals Sum rules in the standard model effective field theory from helicity amplitudes

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Jiayin Gu ◽  
Lian-Tao Wang
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Sum Rules ◽  
High Energy ◽  
Effective Field ◽  
Low Energy ◽  
Tree Level ◽  
The Standard Model ◽  
Helicity Amplitudes

Abstract The dispersion relation of an elastic 4-point amplitude in the forward direction leads to a sum rule that connects the low energy amplitude to the high energy observables. We perform a classification of these sum rules based on massless helicity amplitudes. With this classification, we are able to systematically write down the sum rules for the dimension-6 operators of the Standard Model Effective Field Theory (SMEFT), some of which are absent in previous literatures. These sum rules offer distinct insights on the relations between the operator coefficients in the EFT and the properties of the full theory that generates them. Their applicability goes beyond tree level, and in some cases can be used as a practical method of computing the one loop contributions to low energy observables. They also provide an interesting perspective for understanding the custodial symmetries of the SM Higgs and fermion sectors.

scholarly journals Dark photon bounds in the dark EFT

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Daniele Barducci ◽  
Enrico Bertuzzo ◽  
Giovanni Grilli di Cortona ◽  
Gabriel M. Salla
Keyword(s):  
Degrees Of Freedom ◽  
Dipole Interaction ◽  
Effective Field ◽  
Gauge Bosons ◽  
Abelian Gauge ◽  
Dark Photon ◽  
Mixing Parameter ◽  
The Standard Model ◽  
New States ◽  
Strength Tensor

Abstract Dark photons are massive abelian gauge bosons that interact with ordinary photons via a kinetic mixing with the hypercharge field strength tensor. This theory is probed by a variety of different experiments and limits are set on a combination of the dark photon mass and kinetic mixing parameter. These limits can however be strongly modified by the presence of additional heavy degrees of freedom. Using the framework of dark effective field theory, we study how robust are the current experimental bounds when these new states are present. We focus in particular on the possible existence of a dark dipole interaction between the Standard Model leptons and the dark photon. We show that, under certain assumptions, the presence of a dark dipole modifies existing supernovæ bounds for cut-off scales up to $$ \mathcal{O} $$ O (10–100 TeV). On the other hand, terrestrial experiments, such as LSND and E137, can probe cut-off scales up to $$ \mathcal{O} $$ O (3 TeV). For the latter experiment we highlight that the bound may extend down to vanishing kinetic mixing.

scholarly journals Prospects for direct searches for light Higgs bosons at the ILC with 250 GeV

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
P. Drechsel ◽  
G. Moortgat-Pick ◽  
G. Weiglein
Keyword(s):  
Higgs Boson ◽  
Higgs Sector ◽  
Higgs Bosons ◽  
Gauge Bosons ◽  
Light Higgs Boson ◽  
Lepton Colliders ◽  
Order Of Magnitude ◽  
Model Independent ◽  
Extended Higgs Sector ◽  
Higgs Fields

AbstractThe particle discovered in the Higgs boson searches at the LHC with a mass of about 125 GeV is compatible within the present uncertainties with the Higgs boson predicted in the Standard Model (SM), but it could also be identified with one of the neutral Higgs bosons in a variety of beyond the SM (BSM) theories with an extended Higgs sector. The possibility that an additional Higgs boson (or even more than one) could be lighter than the state that has been detected at 125 GeV occurs generically in many BSM models and has some support from slight excesses that were observed above the background expectations in Higgs searches at LEP and at the LHC. The couplings between additional Higgs fields and the electroweak gauge bosons in BSM theories could be probed by model-independent Higgs searches at lepton colliders. We present a generator-level extrapolation of the limits obtained at LEP to the case of a future $$e^+e^-$$ e + e - collider, both for the search where the light Higgs boson decays into a pair of bottom quarks and for the decay-mode-independent search utilising the recoil method. We find that at the ILC with a centre-of-mass energy of 250 GeV, an integrated luminosity of 500 fb$$^{-1}$$ - 1 and polarised beams, the sensitivity to a light Higgs boson with reduced couplings to gauge bosons is improved by more than an order of magnitude compared to the LEP limits and goes much beyond the projected indirect sensitivity of the HL-LHC with 3000 fb$$^{-1}$$ - 1 from the rate measurements of the detected state at 125 GeV.

scholarly journals SMEFT atlas of ∆F = 2 transitions

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Jason Aebischer ◽  
Christoph Bobeth ◽  
Andrzej J. Buras ◽  
Jacky Kumar
Keyword(s):  
Top Quark ◽  
Effective Field ◽  
Effective Theory ◽  
Tree Level ◽  
Gauge Bosons ◽  
Travel Guide ◽  
The Standard Model ◽  
Individual Contributions ◽  
Model Independent ◽  
The Individual

Abstract We present a model-independent anatomy of the ∆F = 2 transitions K0−$$ {\overline{K}}^0 $$ K ¯ 0 , Bs,d−$$ {\overline{B}}_{s,d} $$ B ¯ s , d and D0−$$ {\overline{D}}^0 $$ D ¯ 0 in the context of the Standard Model Effective Field Theory (SMEFT). We present two master formulae for the mixing amplitude [M12]BSM. One in terms of the Wilson coefficients (WCs) of the Low-Energy Effective Theory (LEFT) operators evaluated at the electroweak scale μew and one in terms of the WCs of the SMEFT operators evaluated at the BSM scale Λ. The coefficients $$ {P}_a^{ij} $$ P a ij entering these formulae contain all the information below the scales μew and Λ, respectively. Renormalization group effects from the top-quark Yukawa coupling play the most important role. The collection of the individual contributions of the SMEFT operators to [M12]BSM can be considered as the SMEFT atlas of ∆F = 2 transitions and constitutes a travel guide to such transitions far beyond the scales explored by the LHC. We emphasize that this atlas depends on whether the down-basis or the up-basis for SMEFT operators is considered. We illustrate this technology with tree-level exchanges of heavy gauge bosons (Z′, G′) and corresponding heavy scalars.

scholarly journals EWPD in the SMEFT to dimension eight

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Tyler Corbett ◽  
Andreas Helset ◽  
Adam Martin ◽  
Michael Trott
Keyword(s):  
Effective Field ◽  
Precision Data ◽  
Data Set ◽  
The Standard Model ◽  
Electroweak Precision ◽  
The Impact ◽  
First Time ◽  
Geometric Formulation ◽  
Electroweak Precision Data ◽  
Theory Error

Abstract We calculate the $$ \mathcal{O}\left({\left\langle {H}^{\dagger }H\right\rangle}^2/{\Lambda}^4\right) $$ O H † H 2 / Λ 4 corrections to LEP electroweak precision data using the geometric formulation of the Standard Model Effective Field Theory (SMEFT). We report our results in simple-to-use interpolation tables that allow the interpretation of this data set to dimension eight for the first time. We demonstrate the impact of these previously unknown terms in the case of a general analysis in the SMEFT, and also in the cases of two distinct models matched to dimension eight. Neglecting such dimension-eight corrections to LEP observables introduces a theoretical error in SMEFT studies. We report some preliminary studies defining such a theory error, explicitly demonstrating the effect of previously unknown dimension-eight SMEFT corrections on LEP observables.

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