Neutral-current constraints on gauge models of weak and electromagnetic interactions

Sehgal and Hung and Sakurai have recently argued that neutrino-hadron neutral-current couplings must lie in one of two allowed regions in coupling-parameter space. We study this conjecture using realistic BNL ν_μ and ν̄_μ spectra in the elastic ν_μp (ν̄_μp) calculations and also study constraints imposed by theq²-distributions. On comparing to gauge models, we find that the Weinberg-Salam and SU(2)_L×SU(2)_R×U(1) models fall within one allowed region, while a vectorlike SU(3)×U(1) model and a hybrid SU(2)×U(1) model with a (u, b)_R doublet fall in the other region.     

The construction of vector-like supersymmetric gauge models of weak and electromagnetic interactions

Despite great efforts and partial successes the situation with respect to spontaneously broken supersymmetric unified gauge models of weak, electromagnetic and strong interactions has remained quite unsatisfactory up to now. Starting from the most simple SU(2) × U(1) cases we exploit possible extensions. This naturally leads to a consideration of vector-like models with—in the first instance—a larger number of multiplets. Although the later can be made massive without spoiling the conservation of fermion number, the additional massive fermions only show parity conserving interactions with all the intermediate vector fields. Therefore models with larger gauge groups are considered: SU(2) × SU(2) × U(1) with two quartets, SU(3) × U(1) with four triplets, and finally SU(3) × SU(2) × U(1) with two sextets of matter fields. None of these can be accepted yet as a true model for physical particles, but it is shown how different negative features in the simple theories may be avoided in the more complicated ones. Thus our results may be considered as an encouraging starting point for investigations of larger gauge groups in supersymmetric models.     

Absolute proton stability in unified models of strong,weak and electromagnetic interactions

We show that the proton can be made absolutely stable, without introducing superheavy bosons, by imposing a global U(1) color symmetry on the Higgs couplings of the theory. Vector-like SU(5) and SU(6) models are discussed in detail.     

Space-time structure of weak and electromagnetic interactions

The generator of electromagnetic gauge transformations in the Dirac equation has a unique geometric interpretation and a unique extension to the generators of the gauge group SU(2) × U(1) for the Weinberg-Salam theory of weak and electromagnetic interactions. It follows that internal symmetries of the weak interactions can be interpreted as space-time symmetries of spinor fields in the Dirac algebra. The possibilities for interpreting strong interaction symmetries in a similar way are highly restricted.     

Purely hadronic weak interactions in unified field theories of the weak and electromagnetic interactions

Non-leptonic weak interactions are investigated in unified gauge theories. A large enhancement of parity violation in nuclei relative to conventional Cabibbo theory is indicated.     

Six-quark model of weak and electromagnetic hadron interactions

The consequences of a six-quark model of weak and electromagnetic hadron interactions are considered for highly inelastic lepton- hadron scattering.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 20–24, May, 1977.I wish to thank V. A. Kuz'min, A. N. Tavkhelidze, and K. G. Chetyrkin for useful discussions.     

Supersymmetry and weak,electromagnetic and strong interactions

We study a possible way to construct supersymmetric theories which could be considered as realistic, excepted that the problem of mass generation for electron, muon and quarks remains. There is a new class of leptons which includes charged ones, and a “photonic neutrino”. Spin $\text{1}\text{2}$-gluons and heavy spin 0- quarks are associated with ordinary vector gluons and quarks.     

A model of weak and electromagnetic interactions of nucleons

Using the concept of spontaneous breakdown of the symmetry in the framework of the Yang-Mills-Higgs-Kibble formalism, the unified model of weak and electromagnetic interactions of point nucleons is suggested.     

Neutral currents in alternative U3 (W)-gauge models of weak and electromagnetic interactions

Two alternative U₃(W)-gauge models are presented. Both agree with the recent Abbott-Barnett fits to the neutrino-nucleon neutral-current data, and with the SLAC measurement of the asymmetry parameter for longitudinally polarised electrondeuteron inelastic scattering. Results for are also found in agreement with the latest measurements. The models differ in the parameterQ _W(Z, N) characterising parity-violation in heavy atoms for which, however, the experimental situation is still unclear.     

Lepton and quark symmetry in weak and electromagnetic interactions

We discuss a three-quark model motivated by lepton-quark analogy. An advantage of this model is that there is no hypercharge-changing neutral current, but Cabibbo suppression has to be explained by dynamical reason.     

Supersymmetric preon models

Subconstituent models with scalar fields are considered. Solutions to 't Hooft's anomaly matching and decoupling equations are given for several cases and, in particular, for preonic theories which are supersymmetric. Possible embeddings of the standard model are briefly described.     

Supersymmetric flavon-chromon models

Using the supersymmetry and R-breaking mechanism induced by N=1 supergravity, we develop the minimal flavon-chromon preonic model where $\text{spin}\text{-}\text{1}\text{2}$ and spin-0 components of four preonic chiral multiplets correspond to flavons and chromons, from which quarks and leptons are made as composites. The emergence of the concepts of flavour and colour, in this minimal model, is synonymous with R and supersymmetry breaking. This breaking also gives a heavy mass to the gaugino, which is necessary for the implementation of the model.     

Proton-neutron mass difference in gauge theories of weak and electromagnetic interactions

The question of cancellation of logarithmic divergence appearing in the proton-neutron mass difference is studied in gauge theories of weak and electromagnetic interactions. In particular, we study the proton-neutron mass difference in three kinds of gauge models. It is found that the contribution from weak hadronic currents in two of the models cancels the logarithmic divergence arising from purely electromagnetic interaction, but as pointed out in the text these two models suffer from some other defects. In one of the models such a cancellation is not possible although the model is otherwise attractive. In this latter case, a mass renormalization counter term exists to absorb the infinity in the mass difference leaving the mass difference essentially a free parameter.     

Parity-violating nuclear interactions and models of the weak Hamiltonian

The derivation of the parity-violating internucleon one-meson-exchange potentials is presented, stressing their connection with models of the weak interactions. Relevant problems concerning second class currents, gauge invariance, off-mass-shell effects, symmetry breaking and multimeson exchanges are discussed. An extensive bibliography of existing literature is also presented.     

Atomic probes of electromagnetic and weak interactions with trapped radioactive atoms

The alkali element francium has a simple electronic structure, and copious amounts of a wide range of isotopes can be produced in present and future rare isotope facilities. The atomic parity violating weak interaction in Fr is 18 times larger than in Cs, which makes it one of the best candidates to search for the effects of the weak interaction and its isotopic dependence. Atomic trapping methods now offer new ways to study these atoms with precision, and we will discuss some of our recent measurements with trapped Fr atoms. Future measurements of the spin-independent weak interaction can be used to test the standard model, but advances in atomic theory and improved understanding of the neutron distribution in nuclei are needed to make progress. We have made precise hyperfine-anomaly measurements in Fr and have shown that they are sensitive to the radial distribution of the neutron magnetization. Measurements of this type can help to constrain the neutron distributions. Future measurements of the spin-dependent weak interaction should allow extraction of the nuclear anapole moments for a sequence of isotopes, and allow separation of the neutron and proton weak interactions between hadrons. Received: 1 May 2001 / Accepted: 4 December 2001     

Aspects of the grand unification of strong,weak and electromagnetic interactions

We study issues arising in attempts to unify strong and other elementary particle interactions. The proton lifetime is estimated in theories with second-order baryon number violation, and found to be O(10³–10⁴) longer than naive dimensional counting suggested. The renormalization of quark and lepton masses below the grand unification mass is considered in some detail. Application is made to the SU(5) model of Georgi and Glashow, and we find strange and bottom quark masses:

$\text{m}{}_{\mathrm{<mtext>s</mtext>}}\text{≈ 0.4–0.5}\text{GeV}\text{, m}{}_{\mathrm{<mtext>b</mtext>}}\text{≈ 4.8–5.6}\text{GeV}$

. Inputs are the values of the strong interactions coupling constant favoured by electroproduction and charmonium analyses, and the observed muon and heavy lepton (τ) masses. These estimates are substantially increased if there are more than six flavours of quark. Symmetry breaking in the SU(5) model is studied, including radiative corrections to the effective Higgs potential.     

A gauge theory of weak and electromagnetic interactions with spontaneous parity breaking

We present a unified gauge theory of weak and electromagnetic interactions in which parity is spontaneously broken together with gauge invariance, by the Higgs mechanism. The gauge group is SU(2) × U(1), and a heavy neutrino is associated with every charged lepton. After the breaking of the original parity-conserving theory, both a purely vector electromagnetic current and the usual V-A charged currents are obtained. Z is coupled to a vector electron current, and the model predicts equal $\text{ν}{}_{\mathrm{\mu }}\text{e}\text{and}\text{ν}{}_{\mathrm{\mu }}\text{e}$ cross sections. Extension to hadrons is made by introducing three charmed quarks p′, n′ and λ′ of the same charges as p, n and λ. All the experimental results $\text{(ν}{}_{\mathrm{\mu }}\text{e}\text{,}\text{ν}{}_{\mathrm{\mu }}\text{e}\text{,}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{e}$, ν_μ and $\text{ν}{}_{\mathrm{\mu }}$ hadron scatterings) are compatible with a value of sin²θ_W of order 0.4.     

Unified theory of weak,strong, electromagnetic,and gravitational interactions

This study will attempt to construct a unified theory of weak, strong, electromagnetic, and gravitational interactions, based on a generalization of Weinberg-Salam theory [1] and a theory proposed previously by the present author [2, 3].Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 25–30, January, 1985.