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The standard model of particle physics is analyzed for the case of a Higgs potential not favoring spontaneous electroweak symmetry breaking to gain insight into the physics of the standard model. Electroweak breaking still takes place, and quarks and leptons still acquire masses but through bosonic technicolor. This ``other'' phase of the standard model exhibits interesting phenomena., Comment: Latex, 22 pages, 2 figures

An approximate vacuum wave functional ${\ensuremath{\Psi}}_{0}$ is proposed for (2+1)-dimensional Yang-Mills theories. Using ${\ensuremath{\Psi}}_{0}$, one can compute the ${0}^{++}$ glueball mass ${M}_{G}$ in terms of the string tension. By using the idea of dimensional reduction, a prediction for ${M}_{G}$ can be made in 3+1 dimensions. One finds ${M}_{G}\ensuremath{\approx}1.5$ GeV.

The annihilation of electron-positron pairs around one second after the big bang distorts the Fermi-Dirac spectrum of neutrino energies. We determine the distortions assuming neutrino mixing with an inverted neutrino-mass hierarchy. Nonequilibrium thermodynamics, the Boltzmann equation, and numerical integration are used to achieve the results. The various types of neutrino behavior are established as a function of masses and mixing angles., Comment: 9 pages in Latex with 6 figures (10 postscript files)

Nuclear simulations of neutrino oscillations in the early Universe are performed for a neutrino-mass hierarchy with the vacuum mass of the second neutrino exceeding that of the first. This situation is equivalent to a normal hierarchy with mixing angle greater than π 4 . We find that a large conversion of electron neutrinos to muon neutrinos occurs, independent of mixing angle. For certain parameter values, this is caused by the MSW effect. In the rest of the parameter region a new mechanism is operative, arising from nonlinear effects involving neutrino-neutrino forward scattering. This nonlinear conversion mechanism causes substantial flavor oscillation even for extremely small mixing angles.

Numerical studies are performed for neutrino oscillations for t > 1 3 seconds after the big bang. The effects of electron, positron and neutrino backgrounds are properly included. Flavor evolution of the neutrino background is dominantly smooth. However, in a certain parameter region, coherent undamped oscillations of the neutrino background are possible. In addition, neutrino CP asymmetry is found to be considerably smaller than expected. Reasons are provided for the above effects and some physical implications are discussed.

We consider oscillations of neutrinos under conditions in which the neutrino density is sufficiently large that neutrino-neutrino interactions cannot be neglected. A formalism is developed to treat this highly nonlinear system. Numerical analysis reveals a rich array of phenomena. In certain gases, a self-induced Mikheyev-Smirnov-Wolfenstein effect occurs in which electron neutrinos are resonantly converted into muon neutrinos. In another relatively low-density gas, an unexpected parametric resonant conversion takes place. Finally, neutrino-neutrino interactions maintain coherence in one system for which a priori one expected decoherence.

It is shown that strings provide a natural theoretical setting for bosonic technicolor. In particular, bosonic technicolor structure arises in a class of strings formulated in four dimensions. An example of a model with three generations and multi-Higgs structure is presented.

Multi-Higgs systems are combined with bosonic technicolor to construct a viable model of TeV physics. In such models, there is potentially a flavor problem in either the supersymmetric or the Higgs sector. However, the naturally larger mass scale for supersymmetry breaking and Higgs masses, which is a salient feature of bosonic technicolor, allows one to resolve the GUT-hierarchy problem without large flavor violation. With a judicious choice of the Higgs system, hierarchies of family masses and mixing angles of the right order of magnitude are achieved without resorting to small Yukawa couplings. Some of these masses and mixing angles are generated by radiative corrections. At energies below 100 GeV the standard model is reproduced, whereas at TeV energies a rich phenomenology of supersymmetric states and techni-hadrons is predicted. We present precise formulas to describe many aspects of the model and its phenomenology at tree and one-loop levels.

Three topics in bosonic technicolor are treated from the viewpoint of the renormalization group: coupling constant unification, linking of the supersymmetry-breaking and technicolor scales, and a naturally light up-Higgs.

We use a multiple Higgs system to analyze the family mass hierarchy problem in bosonic technicolor. Dependence on a wide range of Yukawa couplings, λ, for quark and lepton mass generation is greatly reduced, i.e., λ∼0.1 to 1. Third and second generation masses are produced at tree-level, the latter via a see-saw mechanism. We use radiative corrections as a source for many mixing angles and first generation masses. A hierarchy of family masses with small off-diagonal Kobayashi-Maskawa entries naturally arises. A higher scale of 1–10 TeV for Higgs masses and supersymmetry breaking is needed to alleviate difficulties with flavor-changing effects. Such a large scale is a feature of bosonic technicolor and no fine-tuning is required to obtain electroweak breaking at ∼ 100 GeV. Bosonic technicolor is therefore a natural framework for multi-Higgs systems.

Analytical solutions are obtained to the nonlinear equations describing neutrino oscillations when explicit neutrino-antineutrino asymmetries are present. Such a system occurs in the early Universe if neutrinos have a non-zero chemical potential. Solutions to the equations lead to a new type of coherent behavior governed by two modes. These bimodal solutions provide new insights into dense neutrino gases and into neutrino oscillations in the early Universe, thereby allowing one to surmise the flavor behavior of neutrinos with a non-zero chemical potential., 21 pages in Latex, 11 figures packaged in one Postscript file. Figures also obtainable as 20 gif files at http://www.sci.ccny.cuny.edu/~ssamuel/bimodalfigs.html Revision on 4/19/96 was to pack the figures more sensibly. This paper is to appear in a May issue of Phys. Rev. D

Around one second after the big bang, neutrino decoupling and $e^+$-$e^-$ annihilation distort the Fermi-Dirac spectrum of neutrino energies. Assuming neutrinos have masses and can mix, we compute the distortions using nonequilibrium thermodynamics and the Boltzmann equation. The flavor behavior of neutrinos is studied during and following the generation of the distortion., accepted for publication in Physical Review D

We present analytical solutions to the nonlinear equations describing the behavior of a gas of neutrinos with two flavors. Self-maintained coherent flavor oscillations are shown to occur when the gas density exceeds a critical value determined by the neutrino masses and the mean neutrino energy in the gas. Similar oscillations may have occurred in the early Universe., To appear in Physical Review D, July 1995

We derive the equations that govern neutrino and antineutrino behavior in the early Universe. Results are presented from numerical simulations incorporating nonlinear effects of the neutrino-antineutrino background as well as the leading $\mathrm{CP}$-symmetric and $\mathrm{CP}$-asymmetric terms arising from the interactions with electrons and positrons. A broad spectrum of neutrino and antineutrino behavior is observed, ranging from vacuumlike to smooth. Oscillations exhibiting self-maintained coherence also appear. We identify a variety of neutrino properties arising as a consequence of the nonlinear neutrino self-interactions. The nonlinear effects tend to suppress any $\mathrm{CP}$ asymmetry relative to the linear case. An analytical approximation scheme reproducing bulk neutrino behavior is described. We discuss some physical implications of our results.

By using scalar as opposed to spin- 1 2 quarks and treating spin effects perturbatively, the masses of the lowest lying 0 - and 1 - mesons above 1 GeV (the J/Ψ, η c , D, D ∗ , F, F ∗ , and φ) are calculated to 1%. The masses of the K ∗ , ϱ, and K are respectively obtained to 3%, 8% and 30%. Certain (spin-averaged) linear combinations of baryon masses are also computed. The nucleon-delta result differs from experiment by 8%. For heavier baryons the error is smaller. Scalar lattice QCD seems to be a promising approach to the strong interactions.

A violation of gauge invariance in Witten's open superstring field theory has recently been discovered. We propose a modification which resolves this problem by avoiding the collision of picture-changing operators. Feynman rules for the modified, gauge-invariant theory are presented, including a useful representation for the Ramond propagator. All four-point amplitudes are off-shell finite, agree on-shell with the Polyakov approach and exhibit decoupling of spurious physical states.

A thorough investigation of the non-linear realization of supersymmetry is carried out both in flat space and in curved space (supergravity). A manageable superfield formulation is developed which allows one to evaluate the physical effects of the non-linear field when it is coupled to other multiplets. We present several interesting applications (mostly in the context of supergravity) useful in model building.

A superfield formulation of gauge invariant σ-models, previously written in component form, is given. Both the N = 1 global supersymmetry case and the N = 1 supergravity case are treated. A superfield formulation of σ-models involving abelian and non-abelian N = 2 vector multiplets coupled to N = 2 supergravity is also presented. In the non-abelian case, this is a new class of models.

Superconformal field theory is used to compute off-shell amplitudes for the superstring. Off-shell three- and four-point functions in Witten's superstring field theory are obtained. The problem of gauge invariance due to the associativity anomaly in the bosonic sector is resolved to order g 2 .

The flat-space limit of a supergravity theory involving the Akulov-Volkov field as well as other matter multiplets is found to be an ordinary renormalizable globally supersymmetric theory with explicit soft-breaking mass terms. This allows one to easily construct realistic models of nature which are analyzable at the tree and one-loop level. This is carried out for QED-like and Weinberg-Salam-like models.

By using scalar quarks, we study the quark model on the lattice. Computer simulations are used to measure constituent masses and quark wave functions for a quark-heavy antiquark system. As a function of the quark mass, we compute the charge radius and the value of the wave function at the origin.

A new model building technique is reviewed in which supersymmetry models do not necessarily have boson-fermion particle degeneracy. Possible low-energy phenomenological implications are discussed.

Scalar lattice QCD methods are used to accurately predict the masses of hadrons with beauty, that is, states which contain a b quark. These states have not yet been seen in the laboratory. The accuracy of the predictions (≈ 25 MeV) make the calculation a good test of lattice methods as well as providing useful guidance for experimentalists.

Wave functions for mesons and baryons are computed from lattice QCD. They are used to obtain the electromagnetic properties of the low-lying mesons, including charge radii and electromagnetic form factors. Experimental data for the pion and proton electromagnetic form factor fall close to the theoretical lattice computation. Predictions are made for other states. The lepton width of the ϱ, θ and J/ψ are obtained. The wave functions are also used to obtain estimates for isospin splittings and proton decay.

Using covariant spin fields, the tree amplitude for six massless fermions in the open ten-dimensional superstring is calculated by superconformal field-theoretic methods. The amplitude is presented in a manifestly Lorentz-covariant form.

Low lying s-wave baryon states are analyzed in the context of scalar lattice QCD, that is, lattice QCD with scalar quarks replacing fermion quarks. Except for the proton where we disagree with experiment by 13%, results agree with experiment to better than 4% for the Δ, the Σ, the Σ ∗ , the Λ, the Ξ, the Ξ∗, the Ω, the Σc, and the Λc. In this calculation there were no adjustable parameters, the quark masses and ΛQCD having been already fixed in a previous meson calculation. We also make predictions accurate to 35 MeV for the masses of the Σ c ∗ , the Ωc,, and the Ω c ∗ .

We analyze Hamber's quenched QCD data using a recenty developed semiperturbative reformulation of asymptotic freedom. Scaling is seen quite well. We recompute ${f}_{\ensuremath{\pi}}$, ${m}_{\ensuremath{\rho}}$, and the sum of the current masses ${({m}_{u}+{m}_{d})}_{\stackrel{-}{\mathrm{MS}}}$ ($\stackrel{-}{\mathrm{MS}}$ denotes the modified minimal-subtraction scheme), and find agreement with experiment to within 5%.