scholarly journals Higgs flavor phenomenology in a supersymmetric left-right model with parity

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Syuhei Iguro ◽  
Junichiro Kawamura ◽  
Yuji Omura ◽  
Yoshihiro Shigekami
Keyword(s):  
Higgs Mass ◽  
Fine Tuning ◽  
Tree Level ◽  
Supersymmetric Model ◽  
Parameter Region ◽  
Yukawa Couplings ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
Fermion Masses ◽  
The Standard Model

Abstract In this paper, we focus on the supersymmetric model with left-right (LR) symmetry, that is especially proposed in our previous work [1]. In this model, there are four Higgs doublets in order to realize the Standard Model (SM) fermion masses and the Cabibbo-Kobayashi-Maskawa matrix. The heavy Higgs doublets unavoidably have flavor changing couplings to the SM fermions and induce flavor-changing neutral currents at tree level. We study broader parameter space than the previous work with including the renormalization group corrections to the Yukawa couplings between the LR breaking scale, $$ \mathcal{O} $$ O (1013) GeV, and the supersymmetry breaking scales, $$ \mathcal{O} $$ O (100) TeV. The CP violating observable in K–$$ \overline{K} $$ K ¯ mixing, ϵK, strongly constrains the model, so that heavy Higgs mass should be heavier than $$ \mathcal{O} $$ O (100) TeV. We study the lepton flavor violating (LFV) processes setting heavy Higgs masses to be 170 TeV. The branching ratios of μ → 3e and the μ–e conversion can be larger than 10−16 that could be covered by the future experiments. We also study the degree of fine-tuning in the parameter region that predicts testable LFV processes.

RADIATIVE CORRECTIONS TO HIGGS MASSES IN THE SUPERSYMMETRIC MODEL WITH AN EXTRA FAMILY AND ANTI-FAMILY

1992 ◽  
Vol 07 (03) ◽  
pp. 187-199 ◽  
Author(s):  
TAKEO MOROI ◽  
YASUHIRO OKADA
Keyword(s):  
Mass Spectrum ◽  
Upper Bound ◽  
Higgs Mass ◽  
Blow Up ◽  
Tree Level ◽  
Supersymmetric Model ◽  
Radiative Corrections ◽  
Yukawa Couplings ◽  
Charged Higgs ◽  
Gut Scale

Radiative corrections to Higgs masses are calculated in a supersymmetric standard model with an extra family and its mirror partners. These corrections, in general, depend on the mass spectrum of fermions, bosons and the strength of Yukawa couplings of the extra families. If we assume that the Yukawa couplings do not blow up below the GUT scale, the upper bound of the lightest Higgs mass increases about 12 GeV. We also notice that, in some cases, the charged Higgs mass becomes lighter than that of the tree level prediction.

scholarly journals THE PROBLEM OF NEUTRINO MASSES IN EXTENSIONS OF THE STANDARD MODEL

2001 ◽  
Vol 16 (32) ◽  
pp. 5101-5199 ◽  
Author(s):  
ISABELLA MASINA
Keyword(s):  
Proton Decay ◽  
Fine Tuning ◽  
Neutrino Masses ◽  
Flavor Symmetry ◽  
Mixing Angle ◽  
Grand Unified Theories ◽  
Triplet Splitting ◽  
Fermion Masses ◽  
The Standard Model ◽  
Neutrino Masses And Mixings

We review the problem of neutrino masses and mixings in the context of grand unified theories. After a brief summary of the present experimental status of neutrino physics, we describe how the see-saw mechanism can automatically account for the large atmospheric mixing angle. We provide two specific examples where this possibility is realized by means of a flavor symmetry. We then review in some detail the various severe problems which plague minimal GUT models (like the doublet–triplet splitting and proton-decay) and which force us to investigate the possibility of constructing more elaborate but realistic models. We then show an example of a quasirealistic SUSY SU(5) model which, by exploiting the crucial presence of an Abelian flavor symmetry, does not require any fine-tuning and predicts a satisfactory phenomenology with respect to coupling unification, fermion masses and mixings and bounds from proton decay.

scholarly journals NEW BOUNDS ON THE STRING SCALE FROM FLAVOR PHYSICS

2004 ◽  
Vol 19 (07) ◽  
pp. 497-509 ◽  
Author(s):  
J. SANTIAGO
Keyword(s):  
Lower Bounds ◽  
Flavor Physics ◽  
Scale Up ◽  
Quantum Corrections ◽  
Tree Level ◽  
Mixing Angles ◽  
Realistic Theory ◽  
Flavor Changing ◽  
Fermion Masses ◽  
Supersymmetric Models

We review the very stringent lower bounds on the string scale that arise from flavor considerations in models with intersecting branes. Despite the absence of a realistic flavor structure at tree level, flavor changing interactions induce a non-trivial pattern of fermion masses and mixing angles when quantum corrections are taken into account. The resulting realistic theory of flavor allows us to constrain, in an unambiguous way, the string scale up to levels difficult to reconcile non-supersymmetric models.

Flavons and LFV decays and productions of pseudoscalar mesons

2019 ◽  
Vol 34 (35) ◽  
pp. 1950288
Author(s):  
Tian-Qi Li ◽  
Chong-Xing Yue
Keyword(s):  
Standard Model ◽  
Symmetry Breaking ◽  
Flavor Symmetry ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
Pseudoscalar Mesons ◽  
The Standard Model

Flavons are the dynamic agent of flavor symmetry breaking and have flavor changing couplings to the Standard Model (SM) fermions. We consider their contributions to the lepton flavor violating (LFV) decays [Formula: see text] and [Formula: see text] with [Formula: see text], [Formula: see text] or [Formula: see text] and [Formula: see text] in the simplest flavon model without Higgs-flavon mixing. We find that flavons can produce significant contributions to some of these LFV decay processes.

scholarly journals Revisiting the decoupling effects in the running of the Cosmological Constant

2018 ◽  
Vol 33 (34) ◽  
pp. 1845013
Author(s):  
Oleg Antipin ◽  
Blaženka Melić
Keyword(s):  
Cosmological Constant ◽  
Higgs Mass ◽  
Vacuum Energy ◽  
Fine Tuning ◽  
Simple Extension ◽  
Heavy Particles ◽  
Entire Energy Range ◽  
The Standard Model ◽  
Entire Energy ◽  
Mass Dependent

We revisit the decoupling effects associated with heavy particles in the renormalization group running of the vacuum energy in a mass-dependent renormalization scheme. We find the running of the vacuum energy stemming from the Higgs condensate in the entire energy range and show that it behaves as expected from the simple dimensional arguments, meaning that it exhibits the quadratic sensitivity to the mass of the heavy particles in the infrared regime. The consequence of such a running to the fine-tuning problem with the measured value of the Cosmological Constant is analyzed and the constraint on the mass spectrum of a given model is derived. We show that in the Standard Model (SM) this fine-tuning constraint is not satisfied while in the massless theories this constraint formally coincides with the well-known Veltman condition. We also provide a remarkably simple extension of the SM where saturation of this constraint enables us to predict the radiative Higgs mass correctly. Generalization to constant curvature spaces is also given.

scholarly journals Leptogenesis and fermion mass fit in a renormalizable SO(10) model

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
V. Suryanarayana Mummidi ◽  
Ketan M. Patel
Keyword(s):  
Numerical Solutions ◽  
Double Beta Decay ◽  
Fermion Mass ◽  
Strong Correlations ◽  
Yukawa Couplings ◽  
Mixing Parameters ◽  
Fermion Masses ◽  
The Standard Model ◽  
The Right ◽  
Yukawa Sector

Abstract A non-supersymmetric renormalizable SO(10) model is investigated for its viability in explaining the observed fermion masses and mixing parameters along with the baryon asymmetry produced via thermal leptogenesis. The Yukawa sector of the model consists of complex 10H and $$ {\overline{126}}_H $$ 126 ¯ H scalars with a Peccei-Quinn like symmetry and it leads to strong correlations among the Yukawa couplings of all the standard model fermions including the couplings and masses of the right-handed (RH) neutrinos. The latter implies the necessity to include the second lightest RH neutrino and flavor effects for the precision computation of leptogenesis. We use the most general density matrix equations to calculate the temperature evolution of flavoured leptonic asymmetry. A simplified analytical solution of these equations, applicable to the RH neutrino spectrum predicted in the model, is also obtained which allows one to fit the observed baryon to photon ratio along with the other fermion mass observables in a numerically efficient way. The analytical and numerical solutions are found to be in agreement within a factor of $$ \mathcal{O}(1) $$ O 1 . We find that the successful leptogenesis in this model does not prefer any particular value for leptonic Dirac and Majorana CP phases and the entire range of values of these observables is found to be consistent. The model specifically predicts (a) the lightest neutrino mass $$ {m}_{v_1} $$ m v 1 between 2–8 meV, (b) the effective mass of neutrinoless double beta decay mββ between 4–10 meV, and (c) a particular correlation between the Dirac and one of the Majorana CP phases.

scholarly journals Quark-flavor-changing Higgs decays from a universal extra dimension

2020 ◽  
Vol 35 (24) ◽  
pp. 2050141
Author(s):  
Carlos M. Farrera ◽  
Alejandro Granados-González ◽  
Héctor Novales-Sánchez ◽  
J. Jesús Toscano
Keyword(s):  
Standard Model ◽  
Extra Dimension ◽  
New Physics ◽  
Tree Level ◽  
Universal Extra Dimension ◽  
Loop Level ◽  
Flavor Changing ◽  
The Standard Model ◽  
The One ◽  
Kaluza Klein

Kaluza–Klein fields characterizing, from a four-dimensional viewpoint, the presence of compact universal extra dimensions would alter low-energy observables through effects determined by some compactification scale, [Formula: see text], since the one-loop level, thus being particularly relevant for physical phenomena forbidden at tree level by the Standard Model. This paper explores, for the case of one universal extra dimension, such new-physics contributions to Higgs decays [Formula: see text], into pairs of quarks with different flavors, a sort of decay process which, in the Standard Model, strictly occurs at the loop level. Finite results, decoupling as [Formula: see text], are calculated. Approximate short expressions, valid for large compactification scales, are provided. We estimate that Kaluza–Klein contributions lie below predictions from the Standard Model, being about 2 to 3 orders of magnitude smaller for compactification scales within [Formula: see text].

THE ASSOCIATED PRODUCTION OF THE NEUTRAL TOP-PION WITH A PAIR OF THIRD FAMILY QUARKS AT THE HADRON COLLIDERS

2006 ◽  
Vol 21 (37) ◽  
pp. 2833-2843 ◽  
Author(s):  
XUELEI WANG ◽  
LILI YU ◽  
NAHONG SONG ◽  
WENNA XU
Keyword(s):  
Cross Sections ◽  
The Other ◽  
Tree Level ◽  
Hadron Colliders ◽  
Yukawa Couplings ◽  
The Third ◽  
Flavor Changing ◽  
Associated Production ◽  
Technicolor Model ◽  
The Cross

We study the associated production of the neutral top-pion [Formula: see text] with the third family quarks within the context of the topcolor-assisted technicolor model at the hadron colliders. The studies show that, at the Tevatron, the cross-sections of all these processes are too small to produce enough identified signals. But the cross-sections can be largely enhanced at the LHC. Specially for the processes [Formula: see text] and [Formula: see text], the cross-sections can reach the level of a few hundred fb even a few pb for the light neutral top-pion. With the high yearly luminosity 100 fb-1 at the LHC, over 104 signals can be produced via the above two processes. There exists an ideal flavor-changing mode to detect neutral top-pion, i.e. [Formula: see text], because the SM background of such production mode are very clean. Therefore, we can conclude that neutral top-pion should be observable at the LHC via the processes [Formula: see text] and [Formula: see text]. On the other hand, the statistics available at the LHC via these two processes might be enough to measure the Yukawa couplings [Formula: see text] and [Formula: see text]. Finally, it must be noted that the study of the process [Formula: see text] can give us a good chance to distinguish the TC2 model from the SM and MSSM because there does not exist such similar tree-level favor-changing process in these models.

scholarly journals SUPERSTRING MODELS CHALLENGED BY RARE PROCESSES

1987 ◽  
Vol 02 (03) ◽  
pp. 831-890 ◽  
Author(s):  
B. A. CAMPBELL ◽  
J. ELLIS ◽  
K. ENQVIST ◽  
M. K. GAILLARD ◽  
D. V. NANOPOULOS
Keyword(s):  
Upper Bounds ◽  
Low Energy ◽  
Neutrino Masses ◽  
Dynamical Models ◽  
Gauge Bosons ◽  
Yukawa Couplings ◽  
Flavor Changing ◽  
The Standard Model ◽  
New Interactions ◽  
Matter Fields

Superstring models compactified on Calabi–Yau manifolds contain additional matter fields and gauge bosons beyond those in the Standard Model. The new matter and gauge couplings would make additional contributions to conventional electroweak processes, generate extra flavor-changing neutral interactions, and mediate new interactions leading to proton decay and neutrino masses. We use the phenomenological constraints on such effects to derive upper bounds on Yukawa couplings in low-energy dynamical models inspired by the superstring. We draw attention to the processes which give the best bounds on new Yukawa couplings, and which are those where novel superstring effects might first appear as experimental sensitivity is improved. Our bounds are not sufficient to exclude most superstring models with additional light particles, but do suggest that some couplings are too small to realize certain scenarios for symmetry breaking by radiative corrections.

MSSM PREDICTIONS ON LEPTON FLAVOR VIOLATION DECAYS OF VECTOR MESONS

2012 ◽  
Vol 27 (40) ◽  
pp. 1250230
Author(s):  
JING YANG ◽  
KE-SHENG SUN
Keyword(s):  
Standard Model ◽  
Higgs Mass ◽  
Branching Ratios ◽  
Heavy Flavor ◽  
Lepton Flavor Violation ◽  
Vector Mesons ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Near Future

In the minimal supersymmetric extension of the Standard Model (MSSM) the interactions between the SUSY particles and the Standard Model (SM) particles can contribute to the lepton flavor violation (LFV) decays of vector mesons at loop level. Taking the constraint on the lightest Higgs mass around 126 GeV, we study these decays by a scan over the parameter space which gives the predictions on μ-e conversion and τ→μγ satisfying the experimental bounds. The branching ratios of the vector mesons decays into eμ are strongly suppressed. However, the branching ratios of the heavy flavor mesons decays into τμ can reach the experimental sensitivity in near future. Therefore, the experimental signals of these decays may serve as a probe of the MSSM.

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