STRING THEORY WITH THREE FAMILIES OF CHIRAL FERMIONS

A heterotic string theory is constructed by compactifying directly from 26 to 4 dimensions via a smooth manifold T²²/G. In the low energy limit, there are three families of chiral fermions with exactly the same quantum numbers as thatin the standard supersymmetric SU(3)×SU(2)×XU(1) model. They couple to supergravity and supergauge fields with the gauge symmetry SU(3)_F×SU(3)_c×SU(3)_L×U(1)_YR×U(1)_I3R.     

GRAND UNIFICATION WITH COMPOSITE HIGGS PARTICLES

we discussed an SU(7) grand unified theory with composite scalar particles in this paper. The SU_W(2) confinement model of weak interactions proposed by Abbott and Farhi is contained. We also discussed the effective theory of this model at low energy, which accommodates the SU(2)×U(1) standard model.     

Scale Invariance and Minimum Extension of the SU(2)×U(1) Model

In this note, we discuss a minimum extension of the SU(2)×U(1) model to include both gauge invariance and scale invariance by introducing a complex phase transformation and related complex gauge field, in which the imaginary part corresponds to the Weyl's vector field.     

Z′ mass limits,masses and coupling of higgs bosons,and Z′ decays in an E6 superstring based model

We demonstrate that current phenomenological constraints on Z-Z′ mixing for an E₆ grand unified group with low energy gauge group SU(2)_L×U(1)_Y×U(1)_Y, allow only a narrow range of Higgs vacuum expectation values consistent with possibilities favored by renormalization group expectations. Modest improvements in bounds on this mixing will lead to substantial bounds on the Z′ mass if alternative renormalization group solutions are not found. We then explore the constraints upon relations between Higgs masses in this model. In addition we explore the couplings of these Higgs to the gauge particles of the theory and emphasize the associated implications for Higgs detection in decays of the Z′.     

The Anomaly Coupling of Axigluon and Technicolor Neutral Pseudo Goldstone Bosons

By gauging the anomaly terms according to the gauge group SU(3)_cl x SU(3)_cr × SU(2)_l × U(l)_Y in the technicolor theory, we obtain various possibld anomaly vertices involving technicolor pseudo Goldstone boson and gauge boson (γ, Z, g, g_A). We estimate the decay rates of g_A → gP⁰, g_A → P_A⁰³γ and g_A → P_A⁰³Z.     

Z2 × Z2 Discrete Symmetry in the Left-Right Symmetric Model SU(2)L × SU(2)R × U(l)B-L

From the point that the Higgs fields can be regarded as the gauge fields on a discrete group, we construct a gauge theory of the leftright symmetric model SU(2)_L × SU(2)_R × U(1)_B-L (LRSM) over Z₂ ⊙ Z₂ discrete symmetry.     

A SUPERSYMMETRICAL PREON MODEL WITH SU(2)L × SU(2)R ×U(1)B-L SYMMETRY BROKEN BY COUPLING TO SUPERGRAVITY

A supersymmetrical preon model is proposed. In this model there are Higgs particles which are massless at the scale of confinement of hypercolor due to the supersymmetry and a discrete R symmetry. We show that in this model the low energy gauge symmetry SU(2)_L×SU(2)_R×U(1)_B-L can be broken to U(1)_Q at the scale of supersymmetry breaking by coupling to supergravity.     

Triplication of SU(5) Monopoles

We investigate all spherically symmetric fundamental monopole solutions with fixed topological charge in the SU(5)-->[SU(3) x SU(2) x U(1)]/Z(3) x Z(2) symmetry breaking. We find that there are three solutions that are gauge equivalent but, as we argue, would correspond to physically distinct degrees of freedom in the dualized version of the model. The triplication of monopoles could help us understand the observed family structure of standard model particles.     

Possible structures of neutral currents at PETRA/PEP and LEP

A conservative expansion of the Weinberg-Salam (WS) model to the group SU(2) × U(1) × G increases the structure of neutral currents in the PETRA/PEP/LEP range, while preserving all testable WS predictions at low energies. The special case of SU(2) × U(1) × ?(1) is treated in detail.     

On the phenomenological group in the unified SO(10) model

We analyze possible low energy effects of the additional U(1) contained in the symmetry breaking chain: SO(10)→SU(5) ? U(1) →…, stressing the importance of considering extensions of SU(2) ? U(1) as subgroups of grand unified models, in order to use the relations between the coupling constants provided by the renormalization group. We also investigate the possibility of employing this extra U(1) for an explanation of the possible discrepancy between the experimental value of sin²θ_w and its renormalized value in the SU(5) model.     

Sensitivity of low energy neutral current parameters to new mass scales withinSU(2)×SU(2)×U(1) andSO(10) unification

Sensitivity of low energy weak parameters to possible new mass scales is discussed withinSU(2) ×SU(2)×U(1) models andSO(10) unification. Accuracy better than 0.5% is needed for meaningful tests of the standard model in region up to 1 TeV and of theSU(5) prediction for sin²θ.     

Testing the standard model in terms of a possible strong scalar sector

A complete test of the standard electro-weak model is performed against a background deviation as would be expected from a strong interacting sector. Such a potential deviation can be described by an effective lagrangian containing some parameters essentially related to a spin-one resonance transforming as a triplet under a vector SU(2). The validity limits of the standard model are represented in terms of allowed regions for such parameters. High energy tests will crucially decide on the compatibility of such potential deviations. Alternatively the new scheme can be seen, more fundamentally, as a non-linear realization of the electro-weak symmetry breaking, as opposite to the standard linear realization. This allows for all scalar fields to be absorbed such that in the lagrangian there is no surviving degree of freedom for the Higgs.     

SU(2) × U(1) breaking by vacuum misalignment

Currently two scenarios exist which explain SU(2) × U(1) breaking: the Higgs mechanism, and standard hypercolor schemes. In this paper, a third scenario called “oblique hypercolor” is proposed. A hyperquark condensate is formed which, although kinematically allowed to point in an SU(2) × U(1) preserving direction, is forced by Yukawa interactions of the hyperquarks to misalign by a small angle, breaking SU(2) × U(1). The low energy spectrum involves normal fermions with correct masses, a partially composite Higgs boson, and physical charged scalars.     

Exact potential minimization for a supergravity model

The low energy effective scalar potential arising from the supergravity model proposed by Nilles, Srednicki and Wyler is minimized exactly. Bounds are derived for the parameters of the theory from the requirement that SU(2) × U(1) be broken at the tree level. These results support earlier approximate results.     

Can Natural Flavor Conservation Coexist with CP Violation Mixing Matrix in Multi-Higgs Scalar Models?

A class of multi-Higgs scalar four-family SU(2)×U(1) models is discussed in which tree-level NFC, SCPV and a CP violation mixing matrix coexist together.     

Broken colour symmetry and liberated quarks

We present and discuss a quark model of hadrons, in which local SU(3) gauge symmetry is completely broken and yet asymptotic freedom is presented. There is no infrared slavery in this model, and isolated quarks are free to exist. Colour becomes a global symmetry which is only approximate under SU(3) but nearly exact under SU(2) × U(1), as far as the usual hadron spectroscopy is concerned.     

FINITE TEMPERATURE EFFECTIVE POTENTIAL AND COSMOLOGICAL INFLATION IN WEINBERG-SALAM MODEL

The finite temperature effective potential in SUSY Weinberg-Salam model, proposed by Sohnius, is calculated. The temperature of the phase transition is found approximately. The scale of this temperature is of the order of hiqqs mass, it is the same as that in standard model. There is no influence on the phase transition from the Slavnov term. The cosmological inflationt SU(2)×U(1)epoch in such a model is estimated.     

The phase structure of mixed lattice gauge theories

The mixed compact-non-compact U(1) model is shown to be equivalent to a compact U(1) Higgs model. It is argued that the mixed SO(3)-SU(2) model is dual to an SO(3) gauge theory coupled to a scalar field in the fundamental representation. The degrees of freedom are Z(2) monopoles and charges or, in a dual picture, monopoles and loops. This picture is supported by a Monte Carlo calculation. The implications for the SU(2) transition region are discussed.     

UNIFIED ELECTRO-WEAK MODEL IN SU (3)

In this paper a unified electro-weak model for leptons based on the SU(3) gaugegroup is suggested by means of four kinds of realization for the generators of thegroup. For all low energy electro-weak processes, this model predicts the same resultsas the conventional Weinberg-Salam model does. The Weinberg angle is shown to be sin²θ_w=1/4 in a natural way. When the Higgs self potential respects a discrete symme-try Φ→-Φ, a new conserved quantum number called weak strangeness emerges fromthe model after spontaneous symmetry breaking. In the present model there existanother four heavy vector gauge bosons V^± and U^±± together with some heavyfermions and Higgs scalars, which have non vanishing weak strangeness quantumnumbers. These weak strange particles have no direct couplings with leptons. Theirexistence will not influence the low energy electro-weak processes. Nevertheless, theycan be produced in pairs in high energy collisions and the lightest of them should bestable if the conservation of weak strangeness is exact. The experimental implicationsand the possibility of violation of the conservation of weak strangeness are also dis-cussed.     

A study of SU(3) × SU(2) × U(1) × U(1) as an intermediate energy subgroup of SO(10)

We analyze several patterns of symmetry breaking of SO(10) where SU(3)_c × SU(2) × U(1) × U(1) is an intermediate energy subgroup. Using constraints from the renormalization group and data from neutral-current experiments we show that if the only Higgs used in the low-energy breaking of the theory are those which can give mass to fermions then the possibility of a low intermediate mass scale is ruled out.