scholarly journals OBSERVABLES IN LOW-ENERGY SUPERSTRING MODELS

1986 ◽  
Vol 01 (01) ◽  
pp. 57-69 ◽  
Author(s):  
JOHN ELLIS ◽  
K. ENQVIST ◽  
D.V. NANOPOULOS ◽  
F. ZWIRNER
Keyword(s):  
Gauge Boson ◽  
Vacuum Expectation ◽  
Low Energy ◽  
Effective Theory ◽  
Expectation Values ◽  
Neutral Gauge Boson ◽  
Dynamical Generation ◽  
Gauge Hierarchy ◽  
Sneutrino Mass ◽  
The Masses

We compile phenomenological constraints on the minimal low-energy effective theory which can be obtained from the superstring by Calabi-Yau compactification. Mixing with the single additional neutral gauge boson in this model reduces the mass of the conventional Z0, Field vacuum expectation values are constrained by the experimental upper bound on this shift. Then, requiring the sneutrino mass squared to be positive constrains the scale of supersymmetry breaking more than do lower bounds on the masses of new charged particles and of sparticles. More model-dependent constraints follow from the “naturalness” requirement that observables do not depend sensitively on input parameters. We find a preference for the second neutral gauge boson to weigh ≲320 GeV, [Formula: see text] GeV and [Formula: see text] GeV. Dynamical generation of the gauge hierarchy is possible if mt≲70 GeV, with lower values of mt being favoured.

scholarly journals The EconomicalSU(3)C⊗SU(3)L⊗U(1)XModel

2008 ◽  
Vol 2008 ◽  
pp. 1-74 ◽  
Author(s):  
P. V. Dong ◽  
H. N. Long
Keyword(s):  
Gauge Boson ◽  
Vacuum Expectation ◽  
Mass Splitting ◽  
Lepton Number ◽  
Expectation Values ◽  
Gauge Bosons ◽  
Neutral Gauge Boson ◽  
Goldstone Bosons ◽  
The Standard Model ◽  
Scalar Sector

TheSU(3)C⊗SU(3)L⊗U(1)Xgauge model with minimal scalar sector, two Higgs triplets, is presented in detail. One of the vacuum expectation valuesuis a source of lepton-number violations and a reason for mixing among charged gauge bosons—the standard modelW±and the bilepton gauge bosonsY±, as well as among the neutral non-Hermitian bileptonX0and neutral gauge bosons—theZand the newZ′. An exact diagonalization of the neutral gauge boson sector is derived, and bilepton mass splitting is also given. Because of these mixings, the lepton-number violating interactions exist in both charged and neutral gauge boson sectors. Constraints on vacuum expectation values of the model are estimated andu≃𝒪(1)GeV,v≃vweak=246GeV, andω≃𝒪(1)TeV. In this model, there are three physical scalars, two neutral and one charged, and eight Goldstone bosons—the needed number for massive gauge bosons. The minimal scalar sector can provide all fermions including quarks and neutrinos consistent masses in which some of them require one-loop radiative corrections.

scholarly journals Flavour Anomalies in a U(1) SUSY Extension of the SM

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 191
Author(s):  
Alexander Bednyakov ◽  
Alfiia Mukhaeva
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Gauge Boson ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
The Standard Model ◽  
Meson Mixing ◽  
Additional Anomaly ◽  
Lepton Flavour

Flavour anomalies have attracted a lot of attention over recent years as they provide unique hints for possible New Physics. Here, we consider a supersymmetric (SUSY) extension of the Standard Model (SM) with an additional anomaly-free gauge U(1) group. The key feature of our model is the particular choice of non-universal charges to the gauge boson Z′, which not only allows a relaxation of the flavour discrepancies but, contrary to previous studies, can reproduce the SM mixing matrices both in the quark and lepton sectors. We pay special attention to the latter and explicitly enumerate all parameters relevant for our calculation in the low-energy effective theory. We find regions in the parameter space that satisfy experimental constraints on meson mixing and LHC Z′ searches and can alleviate the flavour anomalies. In addition, we also discuss the predictions for lepton-flavour violating decays B+→K+μτ and B+→K+eτ.

scholarly journals Low energy supergravity revisited (I)

2019 ◽  
Vol 34 (01) ◽  
pp. 1950004
Author(s):  
Gilbert Moultaka ◽  
Michel Rausch de Traubenberg ◽  
Damien Tant
Keyword(s):  
Model Building ◽  
Vacuum Expectation ◽  
Complete Classification ◽  
Low Energy ◽  
Rigorous Approach ◽  
Hidden Sector ◽  
New Type ◽  
The One ◽  
The Masses ◽  
Chiral Superfields

General forms of the Kähler and superpotenials that lead to consistent low energy broken Supersymmetry originating from N[Formula: see text]=[Formula: see text]1 Supergravity have been classified and used for model building since more than three decades. We point out the incompleteness of this classification when hidden sector vacuum expectation values are of the order of the Planck mass. Focusing in this paper mainly on the case of minimal Kähler potential, we adopt a rigorous approach that retrieves on the one hand the known forms, and demonstrate on the other hand the existence of a whole set of new forms for the superpotential of which we give a complete classification. The latter forms involve a new type of chiral superfields having the unusual property of belonging neither to the hidden sector nor to the conventional observable sector. Comparing the obtained forms with the conventional ones, we argue how new possibilities for model building can arise, and discuss the gravity mediation of soft as well as additional hard (but parametrically small) Supersymmetry breaking, in the presence of the new type of chiral superfields. In the simplest case, we study the vacuum structure, characterize the masses and couplings of the scalar components to the hidden and observable sectors and discuss briefly the physical role they could play. In the generic case, we estimate the magnitude and possible consequences of the hard breaking of Supersymmetry in terms of the interplay between hidden and visible sector mass scales.

scholarly journals LEPTON MASS GENERATION AND FAMILY NUMBER VIOLATION MECHANISM IN THE SU(6)L⊗ U(1)Y MODEL

1998 ◽  
Vol 13 (32) ◽  
pp. 5557-5572 ◽  
Author(s):  
UMBERTO COTTI ◽  
RICARDO GAITÁN ◽  
A. HERNÁNDEZ-GALEANA ◽  
WILLIAM A. PONCE ◽  
ARNULFO ZEPEDA
Keyword(s):  
Experimental Data ◽  
Gauge Boson ◽  
Generation Mechanism ◽  
Mass Generation ◽  
Neutral Gauge Boson ◽  
Number Violation ◽  
Charged Leptons ◽  
The Masses ◽  
Lepton Family

Lepton family number violation processes arise in the SU(6) L⊗ U(1) Y model due to the presence of an extra neutral gauge boson, Z′, with family changing couplings, and due to the fact that this model demands the existence of heavy exotic leptons. The mixing of the standard Z with Z′ and the mixing of ordinary leptons with exotic ones induce together family changing couplings on the Z and therefore nonvanishing rates for lepton family number violation processes, such as [Formula: see text], [Formula: see text] and μ→eγ. Additional contributions to the processes μ→eγ and [Formula: see text] are induced from the mass generation mechanism. This last type of contributions may compete with the above one, depending on the masses of the scalars which participate in the diagrams which generate radiatively the masses of the charged leptons. Using the experimental data we compute some bounds for the mixings parameters and for the masses of the scalars.

scholarly journals CURRENT ALGEBRA BASED EFFECTIVE CHIRAL THEORY OF MESONS AND A NEW EW THEORY

2006 ◽  
Vol 21 (04) ◽  
pp. 950-953
Author(s):  
Bing An Li
Keyword(s):  
Gauge Boson ◽  
Current Algebra ◽  
Axial Vector ◽  
Scalar Fields ◽  
Effective Theory ◽  
Vector Mesons ◽  
Chiral Theory ◽  
Gauge Fixing ◽  
The Masses ◽  
A Current

A current algebra based effective chiral theory of pseudoscalar, vector, axial-vector mesons is reviewed. A new mechanism generating the masses and guage fixing terms of gauge boson is revealed from this effective theory. A EW theory without Higgs is proposed. The masses and gauge fixing terms of W and Z are dynamically generated. Three heavy scalar fields are dynamically generated too. They are ghosts.

scholarly journals Gauge Bosons in the 3-3-1 Model with Three Neutrino Singlets

2015 ◽  
Vol 25 (3) ◽  
pp. 227
Author(s):  
Hoang Ngoc Long ◽  
Lam Phu An Huy ◽  
Tran Thanh Thuy ◽  
Ly Thi Tu Tran ◽  
Vu Thi Hoang Yen
Keyword(s):  
Lower Bound ◽  
Decay Width ◽  
Gauge Boson ◽  
W Boson ◽  
Mass Matrix ◽  
Vacuum Expectation ◽  
Expectation Values ◽  
Gauge Bosons ◽  
Proposed Model ◽  
Higgs Fields

We show that the mass matrix of electrically neutral gauge bosons in the recent proposed  model based on \(\mathrm{SU}(3)_C\otimes \mathrm{SU}(3)_L\otimes \mathrm{U}(1)_X\) group with three neutrino singlets [9] has two exact eigenvalues and corresponding eigenvectors. Hence the neutral non-Hermitian gauge boson \(X^0_\mu\) is properly determined.With extra vacuum expectation values of the Higgs fields, there are mixings among charged gauge bosons \(W^\pm\) and \(Y^\pm\) as well as amongneutral gauge bosons \(Z, Z'\) and \(X^0\). From the $W$ boson decay width, we get lower bound on  scale of the model about few TeVs.

scholarly journals PREDICTION OF BEAUTY PARTICLE MASSES WITH THE HEAVY QUARK EFFECTIVE THEORY (II)

1995 ◽  
Vol 10 (06) ◽  
pp. 801-806 ◽  
Author(s):  
U. AGLIETTI
Keyword(s):  
Experimental Data ◽  
Quantitative Estimate ◽  
Low Energy ◽  
Effective Theory ◽  
Recent Experimental Data ◽  
Heavy Quark Effective Theory ◽  
Static Theory ◽  
Charm Hadron ◽  
Hadron Masses ◽  
The Masses

The effective theory for heavy quarks has additional symmetries with respect to QCD, which relate charm and beauty hadron masses. Assuming the spectrum of charmed particles, we predicted in a previous work the masses of some beauty particles. The predictions of the Λb mass, M (Λb) = 5630 MeV , and of the Bs mass, M (Bs) = 5379 MeV , are in agreement with present experimental data. We continue this work using recent experimental data on charm hadron masses. The results are: M (Σb) = 5822±6 MeV , [Formula: see text], M (Ωb) = 6080±7 MeV , [Formula: see text], [Formula: see text], [Formula: see text]. When experimental data for beauty hadron masses are available, a comparison with the theoretical values allows a quantitative estimate of the corrections to the static theory, which contain information on hadron dynamics at low energy.

scholarly journals RENORMALIZATION GROUP EVOLUTION OF NEUTRINO MASSES AND MIXING IN SEESAW MODELS

2010 ◽  
Vol 25 (23) ◽  
pp. 4339-4384 ◽  
Author(s):  
SHAMAYITA RAY
Keyword(s):  
Renormalization Group ◽  
High Energy ◽  
Energy Scale ◽  
Low Energy ◽  
Effective Theory ◽  
Neutrino Masses ◽  
Mixing Parameters ◽  
Group Evolution ◽  
High Energy Scale ◽  
The Masses

We consider different extensions of the Standard Model which can give rise to the small active neutrino masses through seesaw mechanisms, and their mixing. These tiny neutrino masses are generated at some high energy scale by the heavy seesaw fields which then get sequentially decoupled to give an effective dimension-5 operator at the low energy. The renormalization group evolution of the masses and the mixing parameters of the three active neutrinos in the high energy as well as the low energy effective theory is reviewed in this paper.

scholarly journals Neutral Current in Reduced Minimal 3-3-1 Model

2014 ◽  
Vol 24 (2) ◽  
pp. 97 ◽  
Author(s):  
Vu Thi Ngoc Huyen ◽  
Hoang Ngoc Long ◽  
Tran Thanh Lam ◽  
Vo Quoc Phong
Keyword(s):  
Gauge Boson ◽  
Z Boson ◽  
Neutral Current ◽  
Decay Rates ◽  
Gauge Bosons ◽  
Mixing Angle ◽  
Neutral Gauge Boson ◽  
The Third ◽  
Model Based ◽  
The Masses

This work is devoted for gauge boson sector of the recentlyproposed model based on \(\mathrm{SU}(3)_C\otimes \mathrm{SU}(3)_L\otimes \mathrm{U}(1)_X\) group with minimal content of leptons andHiggses. The limits on the masses of the bilepton gauge bosons andon the mixing angle among the neutral ones are deduced. Using theFritzsch anzats on quark mixing, we show that the third family ofquarks should  be different from the first two. We obtain a lowerbound on mass of the new heavy neutral gauge boson as 4.032 TeV.Using data on branching decay rates of the \(Z\) boson, we  can fix the limit to the \(Z\) and $Z^\prime$ mixing angle\(\phi\) as \(-0.001\le\phi\le 0.0003\).

CP-VIOLATION IN A LEFT-RIGHT SYMMETRIC HORIZONTAL FLAVOUR CHIRAL MODEL

1988 ◽  
Vol 03 (06) ◽  
pp. 607-614 ◽  
Author(s):  
KRISHNANATH BANDYOPADHYAY ◽  
ASIM K. RAY ◽  
AMITAVA RAYCHAUDHURI
Keyword(s):  
Cp Violation ◽  
Gauge Boson ◽  
Relative Phase ◽  
Vacuum Expectation ◽  
Chiral Model ◽  
Expectation Values ◽  
Higgs Vacuum ◽  
Boson Exchange ◽  
Text Model ◽  
Left And Right

A horizontal symmetric [Formula: see text] model is studied in the light of spontaneous CP-violation. The left- and right-handed Kobayashi-Maskawa matrices are real and the CP-nonconservation occurs through horizontal gauge boson exchange. To be in accord with experiment, the relative phase between two Higgs vacuum expectation values must be rather small.

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