scholarly journals Two-loop matching of renormalizable operators: general considerations and applications

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Henning Bahl ◽  
Ivan Sobolev
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
High Energy ◽  
Effective Field ◽  
Matching Conditions ◽  
Loop Level ◽  
Doublet Model ◽  
The One ◽  
Diagrammatic Method ◽  
Two Higgs Doublet Model

Abstract Low-energy effective field theories (EFT) encode information about the physics at high energies — i.e., the high-energy theory (HET). To extract this information the EFT and the HET have to be matched to each other. At the one-loop level, general results for the matching of renormalizable operators have already been obtained in the literature. In the present paper, we take a step towards a better understanding of renormalizable operator matching at the two-loop level: focusing on the diagrammatic method, we discuss in detail the various contributions to two-loop matching conditions and compare different approaches to derive them. Moreover, we discuss which observables are best suited for the derivation of matching conditions. As a concrete application, we calculate the $$ \mathcal{O}\left({\alpha}_t{\alpha}_s\right) $$ O α t α s and $$ \mathcal{O}\left({\alpha}_t^2\right) $$ O α t 2 matching conditions of the scalar four-point couplings between the Standard Model (SM) and the Two-Higgs-Doublet Model (THDM) as well as the THDM and the Minimal Supersymmetric Standard Model (MSSM). We use the derived formulas to improve the prediction of the SM-like Higgs mass in the MSSM using the THDM as EFT.

scholarly journals Interplay of New Physics effects in (g − 2)ℓ and h → ℓ+ℓ− — lessons from SMEFT

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Svjetlana Fajfer ◽  
Jernej F. Kamenik ◽  
M. Tammaro
Keyword(s):  
Closed Operator ◽  
Higgs Doublet ◽  
New Physics ◽  
Effective Field ◽  
Tree Level ◽  
Electroweak Symmetry ◽  
Scalar Leptoquark ◽  
Doublet Model ◽  
The One ◽  
Two Higgs Doublet Model

Abstract We explore the interplay of New Physics (NP) effects in (g− 2)ℓ and h→ℓ+ℓ− within the Standard Model Effective Field Theory (SMEFT) framework, including one-loop Renormalization Group (RG) evolution of the Wilson coefficients as well as matching to the observables below the electroweak symmetry breaking scale. We include both the leading dimension six chirality flipping operators including a Higgs and SU(2)L gauge bosons as well as four-fermion scalar and tensor operators, forming a closed operator set under the SMEFT RG equations. We compare present and future experimental sensitivity to different representative benchmark scenarios. We also consider two simple UV completions, a Two Higgs Doublet Model and a single scalar LeptoQuark extension of the SM, and show how tree level matching to SMEFT followed by the one-loop RG evolution down to the electroweak scale can reproduce with high accuracy the (g−2)ℓ and h→ℓ+ℓ− contributions obtained by the complete one- and even two-loop calculations in the full models.

ONE LOOP-INDUCED WZH COUPLING IN THE TWO HIGGS DOUBLET MODEL

1989 ◽  
Vol 04 (28) ◽  
pp. 2757-2766 ◽  
Author(s):  
THOMAS G. RIZZO
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Tree Level ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Charged Higgs ◽  
Doublet Model ◽  
The One ◽  
Two Higgs Doublet Model

Although absent at the tree level in models with only doublet and singlet Higgs representations, the WZH coupling can be induced at the one-loop level. We examine the size of this induced coupling in the two Higgs doublet model due to fermion as well as Higgs/gauge boson loops. Such couplings could provide a new mechanism for charged Higgs production at colliders and are ‘backgrounds’ to new physics beyond the Standard Model. We find, however, that these couplings are very weak for all regions of the parameter space explored.

ONE-LOOP CORRECTIONS TO WWγ AND WWZ VERTICES IN THE THDM

1995 ◽  
Vol 10 (22) ◽  
pp. 3169-3186
Author(s):  
H.B. BENAOUM ◽  
R. BOUAMRANE
Keyword(s):  
Standard Model ◽  
Magnetic Dipole ◽  
Form Factors ◽  
Electric Quadrupole ◽  
Higgs Doublet ◽  
Analytic Expressions ◽  
Doublet Model ◽  
Minimal Standard ◽  
The One ◽  
Two Higgs Doublet Model

The one-loop corrections to the three-boson vertices WWγ and WWZ are studied in the context of the minimal standard model (MSM) as well as the two-Higgs-doublet model (THDM). Analytic expressions of the magnetic dipole and electric quadrupole form factors are given and discussed as functions of various parameters.

scholarly journals Fitting the $$ Zb\overline{b} $$ vertex in the two-Higgs-doublet model and in the three-Higgs-doublet model

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Darius Jurčiukonis ◽  
Luís Lavoura
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Opposite Sign ◽  
Higgs Doublet ◽  
Yukawa Couplings ◽  
The Standard Model ◽  
Doublet Model ◽  
The One ◽  
Two Higgs Doublet Model

Abstract We investigate the new contributions to the parameters gL and gR of the $$ Zb\overline{b} $$ Zb b ¯ vertex in a multi-Higgs-doublet model (MHDM). We emphasize that those contributions generally worsen the fit of those parameters to the experimental data. We propose a solution to this problem, wherein gR has the opposite sign from the one predicted by the Standard Model; this solution, though, necessitates light scalars and large Yukawa couplings in the MHDM.

scholarly journals CP violating hW+W− coupling in the Standard Model and beyond

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Da Huang ◽  
António P. Morais ◽  
Rui Santos
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
Wilson Coefficient ◽  
Loop Contribution ◽  
Loop Level ◽  
The Standard Model ◽  
Order Of Magnitude ◽  
Doublet Model ◽  
The One ◽  
Model Benchmark

Abstract Inspired by the recent development in determining the property of the observed Higgs boson, we explore the CP-violating (CPV) $$ -{c}_{\mathrm{CPV}}{hW}^{+\mu \nu}{\tilde{W}}_{\mu \nu}^{-}/\upsilon $$ − c CPV hW + μν W ˜ μν − / υ coupling in the Standard Model (SM) and beyond, where W±μν and $$ {\tilde{W}}^{\pm \mu \nu} $$ W ˜ ± μν denote the W-boson field strength and its dual. To begin with, we show that the leading-order SM contribution to this CPV vertex appears at two-loop level. By summing over the quark flavor indices in the two loop integrals analytically, we can estimate the order of the corresponding Wilson coefficient to be $$ {c}_{\mathrm{CPV}}^{\mathrm{SM}}\sim \mathcal{O}\left({10}^{-23}\right) $$ c CPV SM ∼ O 10 − 23 , which is obviously too small to be probed at the LHC and planned future colliders. Then we investigate this CPV hW+W− interaction in two Beyond the Standard Model benchmark models: the left-right model and the complex 2-Higgs doublet model (C2HDM). Unlike what happens for the SM, the dominant contributions in both models arise at the one-loop level, and the corresponding Wilson coefficient can be as large as of $$ \mathcal{O} $$ O (10−9) in the former model and of $$ \mathcal{O} $$ O (10−3) for the latter. In light of such a large CPV effect in the hW+W− coupling, we also give the formulae for the leading one-loop contribution to the related CPV hZZ effective operator in the complex 2-Higgs doublet model. The order of magnitude of the Wilson coefficients in the C2HDM may be within reach of the high-luminosity LHC or planned future colliders.

scholarly journals ON THE ORIGIN OF APPROXIMATE CUSTODIAL SYMMETRY IN THE TWO-HIGGS DOUBLET MODEL

2009 ◽  
Vol 24 (30) ◽  
pp. 5587-5637 ◽  
Author(s):  
C. D. FROGGATT ◽  
R. NEVZOROV ◽  
H. B. NIELSEN ◽  
D. THOMPSON
Keyword(s):  
Higgs Boson ◽  
Top Quark ◽  
Higgs Doublet ◽  
High Energy ◽  
Boson Mass ◽  
Multiple Point ◽  
Large Set ◽  
Enhanced Production ◽  
Doublet Model ◽  
Two Higgs Doublet Model

We argue that the consistent implementation of the multiple point principle (MPP) in the general nonsupersymmetric two-Higgs doublet model (2HDM) can lead to a set of approximate global custodial symmetries that ensure CP conservation in the Higgs sector and the absence of flavor changing neutral currents (FCNC) in the considered model. In particular, the existence of a large set of degenerate vacua at some high energy scale Λ caused by the MPP can result in approximate U(1) and Z2 symmetries that suppress FCNC and CP-violating interactions in the 2HDM. We explore the renormalization group (RG) flow of the Yukawa and Higgs couplings within the MPP inspired 2HDM with approximate custodial symmetries and show that the solutions to the RG equations are focused near quasifixed points at low energies if the MPP scale Λ is relatively high. We study the Higgs spectrum and couplings near the quasifixed point at moderate values of tan β and compute a theoretical upper bound on the lightest Higgs boson mass. If Λ ≳ 1010 GeV the lightest CP-even Higgs boson is always lighter than 125 GeV. When the MPP scale is low, the mass of the lightest Higgs particle can reach 180–220 GeV while its coupling to the top quark can be significantly larger than in the SM, resulting in the enhanced production of Higgs bosons at the LHC. Other possible scenarios that appear as a result of the implementation of the MPP in the 2HDM are also discussed.

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