scholarly journals THE MINIMAL SUPERSYMMETRIC STANDARD MODEL

1996 ◽  
Vol 11 (08) ◽  
pp. 599-613 ◽  
Author(s):  
CSABA CSÁKI
Keyword(s):  
Standard Model ◽  
Mass Parameter ◽  
Baryon Number ◽  
Higgs Doublet ◽  
Particle Content ◽  
Anomaly Cancellation ◽  
Flavor Changing ◽  
Quantum Numbers ◽  
Parity Conservation ◽  
The One

The structure of the MSSM is reviewed. We first motivate the particle content of the theory by examining the quantum numbers of the known standard model particles and by the requirement of anomaly cancellation. Once the particle content is fixed we can write down the most general renormalizable superpotential. However such a superpotential will contain terms breaking lepton and baryon number which leads us to the concept of R-parity conservation. The question of supersymmetry breaking is discussed next. We list the possible soft breaking terms. However the Lagrangian involving the most general soft breaking terms is phenomenologically intractable because of the appearance of many new parameters. It also leads to some unacceptable predictions. To reduce the number of parameters we restrict ourselves to the case with universal soft breaking terms at the GUT scale. We motivate the need for universal soft breaking terms by the apparent unification of gauge couplings in the MSSM and by the absence of flavor changing neutral currents. Then we discuss radiative electroweak symmetry breaking. Radiative breaking arises because the one-loop corrections involving the large top Yukawa coupling change the sign of the soft breaking mass parameter of the up-type Higgs doublet, this way introducing a nontrivial minimum in the Higgs potential. Finally we give an overview of the possible mixings in the MSSM and enumerate the physical (mass eigenstate) fields together with the mass matrices.

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.

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.

scholarly journals ELECTROWEAK QUARK–LEPTON SYMMETRY AND WEAK TOPOLOGICAL-CHARGE CONFINEMENT IN THE STANDARD MODEL WITH DIRAC NEUTRINOS

2007 ◽  
Vol 22 (21) ◽  
pp. 3669-3691 ◽  
Author(s):  
ERNESTO A. MATUTE
Keyword(s):  
Standard Model ◽  
Topological Charge ◽  
Additive Group ◽  
Weak Field ◽  
Anomaly Cancellation ◽  
Charge Quantization ◽  
Lepton Charge ◽  
The Standard Model ◽  
The One ◽  
Electroweak Model

The standard electroweak model with Dirac neutrinos is extended by way of the principles of electroweak quark–lepton symmetry and weak topological-charge confinement to account for quark–lepton charge relations which, if not accidental, are indicative of charge structures. A mixing in quarks and leptons of underlying integer local charges with integer weak topological charges associated with an additive group Z3, fixed by the anomaly cancellation requirement, is discussed. It is found that the electroweak difference between topological quarks and leptons is the nonequivalence between the topological vacua of their weak field configurations, produced by a four-instanton which carries the topological charge, induces the universal fractional piece of charge distinguishing quarks from leptons, and breaks the underlying symmetry. The constituent quarks of the standard model appear as coming from topological quarks, via the weak four-instanton event. Dual transitions occur for leptons. It is shown that several other fundamental problems left open in the standard electroweak model with Dirac neutrinos are solved: the one-to-one correspondence between quark and lepton flavors, the existence of three generations, the conservation and ungauging of B-L, the electric charge quantization, and the confinement of fractional electric charges.

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].

scholarly journals Electroweak corrections to the fermionic decays of heavy Higgs states

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Florian Domingo ◽  
Sebastian Paßehr
Keyword(s):  
Standard Model ◽  
Scalar Fields ◽  
Higgs Doublet ◽  
New Physics ◽  
Higgs Bosons ◽  
Light Higgs Boson ◽  
Collider Phenomenology ◽  
The One ◽  
Three Body ◽  
Electroweak Corrections

Abstract Extensions of the standard model often come with additional, possibly electroweakly charged Higgs states, the prototypal example being the Two-Higgs-Doublet Model. While collider phenomenology does not exclude the possibility for some of these new scalar fields to be light, it is relatively natural to consider masses in the multi-TeV range, in which case the only remaining light Higgs boson automatically receives SM-like properties. The appearance of a hierarchy between the new-physics states and the electroweak scale then leads to sizable electroweak corrections, e. g. in the decays of the heavy Higgs bosons, which are dominated by effects of infrared type, namely Sudakov logarithms. Such radiative contributions obviously affect the two-body decays, but should also be paired with the radiation of electroweak gauge bosons (or lighter Higgs bosons) for a consistent picture at the one-loop order. Resummation of the leading terms is also relatively easy to achieve. We re-visit these questions in the specific case of the fermionic decays of heavy Higgs particles in the Next-to-Minimal Supersymmetric Standard Model, in particular pointing out the consequences of the three-body final states for the branching ratios of the heavy scalars.

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 $$U(1)'$$ extensions of the $$\mu \nu \mathrm{SSM}$$

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
J. A. Aguilar-Saavedra ◽  
I. Lara ◽  
D. E. López-Fogliani ◽  
C. Muñoz
Keyword(s):  
Dark Matter ◽  
Domain Wall ◽  
Standard Model ◽  
Gauge Group ◽  
Parameter Space ◽  
Baryon Number ◽  
Anomaly Cancellation ◽  
The Standard Model ◽  
Different Types ◽  
Visible Sector

AbstractIn the $$\mu \nu $$ μ ν SSM, the presence of R-parity violating couplings involving right-handed (RH) neutrinos solves simultaneously the $$\mu $$ μ - and $$\nu $$ ν -problems. We explore extensions of the $$\mu \nu $$ μ ν SSM adding a $$U(1)'$$ U ( 1 ) ′ gauge group, which provides the RH neutrinos with a non-vanishing charge. In these models, dubbed U$$\mu \nu $$ μ ν SSM, the anomaly cancellation conditions impose the presence of exotic quarks in the spectrum that are vector-like under the standard model (SM) gauge group: either three pairs SU(2) quark singlets, or a pair of quark singlets together with a pair of quark doublets. Several singlets under the SM group can also be present, with the $$U(1)'$$ U ( 1 ) ′ charges making distinctions among them, and therefore allowing different types of couplings. Some of these singlets dynamically generate Majorana masses for the RH neutrinos, and others can be candidates for dark matter. The useful characteristics of models with $$U(1)'$$ U ( 1 ) ′ s are also present in U$$\mu \nu $$ μ ν SSM models: baryon-number-violating operators as well as explicit Majorana masses and $$\mu $$ μ terms are forbidden, and the domain wall problem is avoided. The phenomenology of U$$\mu \nu $$ μ ν SSM models is very rich. We analyze the experimental constraints on their parameter space, specially on the mass and mixing of the new $$Z'$$ Z ′ boson. In addition to the exotic quarks, which can hadronize inside the detector or decay producing SM particles, the U$$\mu \nu $$ μ ν SSM models can also have new signals such as decays of the $$Z'$$ Z ′ to sparticle pairs like right sneutrinos, charginos or neutralinos. Besides, $$Z'$$ Z ′ and Higgs mediated annihilations and interactions with the visible sector of WIMP dark matter particles, can also be present.

scholarly journals THE DECAY b→sγ IN THE 3–3–1 MODEL

1996 ◽  
Vol 11 (13) ◽  
pp. 2263-2280 ◽  
Author(s):  
JYOTI AGRAWAL ◽  
PAUL H. FRAMPTON ◽  
JAMES T. LIU
Keyword(s):  
Decay Rate ◽  
Higgs Mass ◽  
Higgs Doublet ◽  
The Other ◽  
Anomaly Cancellation ◽  
The Third ◽  
Flavor Changing ◽  
Charged Higgs ◽  
Doublet Model ◽  
Two Higgs Doublet Model

The 3–3–1 model, based on the gauge group SU (3)c× SU (3)L× U (1)X, makes a natural prediction of three generations based on anomaly cancellation. Since this is accomplished by incorporating the third family of quarks differently from the other two, it leads to potentially large flavor-changing neutral currents. A sensitive place to look for such effects is the flavor-changing b→sγ decay, which has recently been measured at CLEO. We compute this decay rate in the 3–3–1 model and compare it with that of the two-Higgs-doublet model, a subset of the full 3–3–1 model. We find that the additional 3–3–1 physics weakens the bound on the charged Higgs mass from MH+>290 GeV to MH+≳120 GeV .

scholarly journals A Review of the Exceptional Supersymmetric Standard Model

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 557
Author(s):  
Stephen F. King ◽  
Stefano Moretti ◽  
Roman Nevzorov
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Supersymmetric Standard Model ◽  
Hadron Collider ◽  
Gauge Coupling ◽  
Higgs Bosons ◽  
Anomaly Cancellation ◽  
Flavor Changing ◽  
Low Energies ◽  
The Right

Local supersymmetry (SUSY) provides an attractive framework for the incorporation of gravity and unification of gauge interactions within Grand Unified Theories (GUTs). Its breakdown can lead to a variety of models with softly broken SUSY at low energies. In this review article, we focus on the SUSY extension of the Standard Model (SM) with an extra U ( 1 ) N gauge symmetry originating from a string-inspired E 6 GUTs. Only in this U ( 1 ) extension of the minimal supersymmetric standard model (MSSM) can the right-handed neutrinos be superheavy, providing a mechanism for the baryon asymmetry generation. The particle content of this exceptional supersymmetric standard model (E 6 SSM) includes three 27 representations of the E 6 group, to ensure anomaly cancellation. In addition it also contains a pair of S U ( 2 ) W doublets as required for the unification of gauge couplings. Thus, E 6 SSM involves exotic matter beyond the MSSM. We consider symmetries that permit suppressing flavor changing processes and rapid proton decay, as well as gauge coupling unification, the gauge symmetry breaking and the spectrum of Higgs bosons in this model. The possible Large Hadron Collider (LHC) signatures caused by the presence of exotic states are also discussed.

scholarly journals $$U(1)_{B_3-L_2}$$ explanation of the neutral current $$B-$$anomalies

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
B. C. Allanach
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
Vector Boson ◽  
Baryon Number ◽  
Higgs Bosons ◽  
Complex Scalar ◽  
Quantum Numbers ◽  
The Standard Model ◽  
Model Predictions ◽  
Rule Out

AbstractWe investigate a speculative short-distance force, proposed to explain discrepancies observed between measurements of certain neutral current decays of B hadrons and their Standard Model predictions. The force derives from a spontaneously broken, gauged $$U(1)_{B_3-L_2}$$ U ( 1 ) B 3 - L 2 extension to the Standard Model, where the extra quantum numbers of Standard Model fields are given by third family baryon number minus second family lepton number. The only fields beyond those of the Standard Model are three right-handed neutrinos, a gauge field associated with $$U(1)_{B_3-L_2}$$ U ( 1 ) B 3 - L 2 and a Standard Model singlet complex scalar which breaks $$U(1)_{B_3-L_2}$$ U ( 1 ) B 3 - L 2 , a ‘flavon’. This simple model, via interactions involving a TeV scale force-carrying $$Z^\prime $$ Z ′ vector boson, can successfully explain the neutral current $$B-$$ B - anomalies whilst accommodating other empirical constraints. In an ansatz for fermion mixing, a combination of up-to-date $$B-$$ B - anomaly fits, LHC direct $$Z^\prime $$ Z ′ search limits and other bounds rule out the domain 0.15 $$\hbox {TeV}< M_{Z^\prime }<$$ TeV < M Z ′ < 1.9 TeV at the $$95\%$$ 95 % confidence level. For more massive $$Z^\prime $$ Z ′ s, the model possesses a flavonstrahlung signal, where pp collisions produce a $$Z^\prime $$ Z ′ and a flavon, which subsequently decays into two Higgs bosons.

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