scholarly journals QCD corrections in two-Higgs-doublet extensions of the standard model with minimal flavor violation

2010 ◽  
Vol 81 (7) ◽  
Author(s):  
G. Degrassi ◽  
P. Slavich
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
Minimal Flavor Violation ◽  
Flavor Violation ◽  
The Standard Model

scholarly journals IMPLICATION OF sin 2β FROM GLOBAL FIT AND B→J/ψKS

2001 ◽  
Vol 16 (28) ◽  
pp. 4547-4565 ◽  
Author(s):  
YUE-LIANG WU ◽  
YU-FENG ZHOU
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Current Data ◽  
Beyond The Standard Model ◽  
Flavor Violation ◽  
Flavor Changing ◽  
The Standard Model ◽  
Global Fit ◽  
The One

The measurement of sin 2β is discussed within and beyond the standard model. In the presence of new physics, the angle β extracted from the global fit (denoted by [Formula: see text]) and the one extracted from B→J/ψKS(denoted by βJ/ψ) are in general all different from the "true" angle β which is the weak phase of CKM matrix element [Formula: see text]. Possible new physics effects on the ratio [Formula: see text] is studied and parametrized in a most general form. It is shown that the ratio Rβmay provide a useful tool in probing new physics. The experimental value of Rβis obtained through an update of the global fit of the unitarity triangle with the latest data and found to be less than unity at 1σ level. The new physics effects on Rβfrom the models with minimum flavor violation (MFV) and the standard model with two-Higgs-doublet (S2HDM) are studied in detail. It is found that the MFV models seem to give a relative large value Rβ≥1. With the current data, this may indicate that this kind of new physics may be disfavored and alternative new physics with additional phases appears more relevant. As an illustration for models with additional phase beyond CKM phase, the S2HDM effects on Rβare studied and found to be easily coincide with the data due to the flavor changing neutral Higgs interaction.

scholarly journals Positivity bounds on Minimal Flavor Violation

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Quentin Bonnefoy ◽  
Emanuele Gendy ◽  
Christophe Grojean
Keyword(s):  
Standard Model ◽  
Effective Field ◽  
Minimal Flavor Violation ◽  
Ckm Matrix ◽  
Yukawa Couplings ◽  
Flavor Violation ◽  
Higher Dimensional ◽  
The Standard Model ◽  
The One ◽  
Yukawa Sector

Abstract From general analyticity and unitarity requirements on the UV theory, positivity bounds on the Wilson coefficients of the dimension-8 operators composed of 4 fermions and two derivatives appearing in the Standard Model Effective Field Theory have been derived recently. We explore the fate of these bounds in the context of models endowed with a Minimal Flavor Violation (MFV) structure, models in which the flavor structure of higher dimensional operators is inherited from the one already contained in the Yukawa sector of the Standard Model Lagrangian. Our goal is to check whether the general positivity bounds translate onto bounds on the Yukawa coefficients and/or on elements of the CKM matrix. MFV fixes the coefficients of dimension-8 operators up to some multiplicative flavor-blind factors and we find that, in the most generic setup, the freedom left by those unspecified coefficients is enough as not to constrain the parameters of the renormalizable Yukawa sector. On the contrary, the latter shape the allowed region for the former. Requiring said overall coefficients to take natural $$ \mathcal{O}(1) $$ O 1 values could give rise to bounds on the Yukawa couplings. Remarkably, at leading order in an expansion in powers of the Yukawa matrices, no bounds on the CKM entries can be retrieved.

scholarly journals Freezing In with lepton flavored fermions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Giancarlo D'Ambrosio ◽  
Shiuli Chatterjee ◽  
Ranjan Laha ◽  
Sudhir Kumar Vempati
Keyword(s):  
Standard Model ◽  
Direct Detection ◽  
Lepton Number ◽  
Minimal Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Quantum Numbers ◽  
The Standard Model ◽  
Lepton Number Violating

Dark, chiral fermions carrying lepton flavor quantum numbers are natural candidates for freeze-in. Small couplings with the Standard Model fermions of the order of lepton Yukawas are `automatic' in the limit of Minimal Flavor Violation. In the absence of total lepton number violating interactions, particles with certain representations under the flavor group remain absolutely stable. For masses in the GeV-TeV range, the simplest model with three flavors, leads to signals at future direct detection experiments like DARWIN. Interestingly, freeze-in with a smaller flavor group such as SU(2) is already being probed by XENON1T.

scholarly journals Searching for charged lepton flavor violation at ep colliders

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Stefan Antusch ◽  
A. Hammad ◽  
Ahmed Rashed
Keyword(s):  
Standard Model ◽  
Charged Lepton ◽  
Neutral Current ◽  
Effective Theory ◽  
Theory Approach ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Order Of Magnitude

Abstract We investigate the sensitivity of electron-proton (ep) colliders for charged lepton flavor violation (cLFV) in an effective theory approach, considering a general effective Lagrangian for the conversion of an electron into a muon or a tau via the effective coupling to a neutral gauge boson or a neutral scalar field. For the photon, the Z boson and the Higgs particle of the Standard Model, we present the sensitivities of the LHeC for the coefficients of the effective operators, calculated from an analysis at the reconstructed level. As an example model where such flavor changing neutral current (FCNC) operators are generated at loop level, we consider the extension of the Standard Model by sterile neutrinos. We show that the LHeC could already probe the LFV conversion of an electron into a muon beyond the current experimental bounds, and could reach more than an order of magnitude higher sensitivity than the present limits for LFV conversion of an electron into a tau. We discuss that the high sensitivities are possible because the converted charged lepton is dominantly emitted in the backward direction, enabling an efficient separation of the signal from the background.

scholarly journals HIDING THE EXISTENCE OF A FAMILY SYMMETRY IN THE STANDARD MODEL

2005 ◽  
Vol 20 (36) ◽  
pp. 2767-2774 ◽  
Author(s):  
ERNEST MA
Keyword(s):  
Standard Model ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Higgs Sector ◽  
Higgs Doublet ◽  
Neutrino Mass Matrix ◽  
Tree Level ◽  
Family Symmetry ◽  
The Standard Model

If a family symmetry exists for the quarks and leptons, the Higgs sector is expected to be enlarged to be able to support the transformation properties of this symmetry. There are, however, three possible generic ways (at tree level) of hiding this symmetry in the context of the Standard Model with just one Higgs doublet. All three mechanisms have their natural realizations in the unification symmetry E6 and one in SO (10). An interesting example based on SO (10)×A4 for the neutrino mass matrix is discussed.

EFFECTS OF THE CHARGED HIGGS BOSON ON THE b→sl+l− DECAY

1989 ◽  
Vol 04 (20) ◽  
pp. 1945-1954 ◽  
Author(s):  
M. CIUCHINI
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Higgs Sector ◽  
Higgs Doublet ◽  
Charged Higgs Boson ◽  
The Standard Model ◽  
Charged Higgs ◽  
Free Parameters

The 2H model that resembles the Higgs sector of the minimal N=1 SUSY version of the standard model is considered and the contribution of the charged Higgs boson to the rate of the b→sl+l− transition is studied as a function of the free parameters MH, Mt and the squared two Higgs doublet v.e.v. ratio r. It is shown that this process can be suppressed by the charged Higgs boson contribution and that in general it is not very sensitive to its presence unless (SUSY-forbidden) values of r>1 are assumed.

scholarly journals Higgs searches beyond the Standard Model

2014 ◽  
Vol 31 ◽  
pp. 1460288 ◽  
Author(s):  
R. Mankel ◽  
Keyword(s):  
Standard Model ◽  
Higgs Sector ◽  
Higgs Doublet ◽  
Higgs Bosons ◽  
Supersymmetric Model ◽  
Beyond The Standard Model ◽  
Model Interpretation ◽  
The Standard Model ◽  
Extended Higgs Sectors ◽  
Minimal Supersymmetric Model

While the existence of a Higgs boson with a mass near 125 GeV has been clearly established, the detailed structure of the entire Higgs sector is yet unclear. Besides the Standard Model interpretation, various possibilities for extended Higgs sectors are being considered. The minimal supersymmetric extension (MSSM) features two Higgs doublets resulting in five physical Higgs bosons, which are subject to direct searches. Alternatively, more generic Two-Higgs Doublet models (2HDM) are used for the interpretation of results. The Next-to-Minimal Supersymmetric Model (NMSSM) has a more complex Higgs sector with seven physical states. Also exotic Higgs bosons decaying to invisible final states are considered. This article summarizes recent findings based on results from collider experiments.

scholarly journals The dark phases of the N2HDM

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Isabell Engeln ◽  
Pedro Ferreira ◽  
M. Margarete Mühlleitner ◽  
Rui Santos ◽  
Jonas Wittbrodt
Keyword(s):  
Dark Matter ◽  
Large Hadron Collider ◽  
Standard Model ◽  
Hadron Collider ◽  
Higgs Doublet ◽  
Tree Level ◽  
Vacuum Structure ◽  
The Standard Model ◽  
Doublet Model ◽  
Specific Phase

Abstract We discuss the dark phases of the Next-to-2-Higgs Doublet model. The model is an extension of the Standard Model with an extra doublet and an extra singlet that has four distinct CP-conserving phases, three of which provide dark matter candidates. We discuss in detail the vacuum structure of the different phases and the issue of stability at tree-level of each phase. Taking into account the most relevant experimental and theoretical constraints, we found that there are combinations of measurements at the Large Hadron Collider that could single out a specific phase. The measurement of h125 → γγ together with the discovery of a new scalar with specific rates to τ+τ− or γγ could exclude some phases and point to a specific phase.

scholarly journals Family Symmetries and Multi Higgs Doublet Models

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 156
Author(s):  
Bartosz Dziewit ◽  
Jacek Holeczek ◽  
Sebastian Zając ◽  
Marek Zrałek
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
Family Symmetry ◽  
The Standard Model ◽  
Schur’S Lemma ◽  
Finite Subgroups ◽  
Free Parameters ◽  
Schur's Lemma

Imposing a family symmetry on the Standard Model in order to reduce the number of its free parameters, due to the Schur’s Lemma, requires an explicit breaking of this symmetry. To avoid the need for this symmetry to break, additional Higgs doublets can be introduced. In such an extension of the Standard Model, we investigate family symmetries of the Yukawa Lagrangian. We find that adding a second Higgs doublet (2HDM) does not help, at least for finite subgroups of the U ( 3 ) group up to the order of 1025.

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.

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