Modern Physics Letters A

The main phenomenological aspects of the Higgs bosons are briefly reviewed in the context of the Standard Model and in models with an "extended" Higgs sector. Among the latter, special emphasis is made on the Two-Doublet Model and, particularly, the Minimal Supersymmetric Model.

A two-center parametrization with smoothed neck is used to describe the shapes during the fission process of ²³⁴U in a wide range of mass asymmetry (cold fission with ¹⁰⁰Zr fragment, ²⁸Mg radioactivity and α-decay). The optimum fission path has been found by minimizing the action integral. The neck influence is stronger for lower mass asymmetry.

The Green's function G(x; x′) for a two flavor/mass oscillating neutrino propagating through a lattice of Delta-function potentials is evaluated. The Green's function is readily put in the form of a physically interesting path integral. In the limit that the interparticle spacing is very much smaller than the vacuum oscillation length, the usual mean field result is recovered.

The Gaussian effective potential for the supersymmetric Liouville model is computed both at zero temperature and at a finite temperature. It is noted that the supersymmetric Liouville theory, just like the ordinary Liouville model, does not possess a translationally invariant ground state. The broken translational symmetry is not restored by temperature effects. The supersymmetric Liouville theory is also non-trivial.

We show that the k = 1 two-dimensional gravity amplitudes at genus 3 agree precisely with the results from intersection theory on moduli space. Predictions for the genus 4 intersection numbers follow easily from the two-dimensional gravity theory.

We present arguments relating certain super-KP systems to minimal superdiscrete series models coupled to supergravity. The even members of the series are closely related to bosonic minimal models coupled to ordinary gravity, and are described by generalized KdV flows (with no free non-perturbative parameters). In particular, the theory is seen to be a topological field theory closely related to the bosonic one at c = −2. There are indications that supersymmetry is broken for the odd members of the series.

We show that there is a direct connection between the existence of an ambiguity in the BJL definition of a double commutator and the violation of the Jacobi identity.

A classification is made of ℤ_N (N = 2, 3, 4, and 6) orbifolds which break space-time supersymmetry. Of these, two are promising for a chiral theory. A classification is then made of all possible four-dimensional gauge groups which are possible from the two promising orbifolds.

It is suggested that the quantum geometry of asymptotically locally Euclidean spaces underlies the dynamics of superstrings moving on Calabi-Yau manifolds. In particular, it is pointed out that solving the Wheeler-DeWitt equation is akin to using a neural network to color maps on a Riemann surface. In the infrared limit such map colorings are formally equivalent to Calabi-Yau vacua for superstrings.

The leading non-logarithmic contribution which arises in the real part of the Wilson coefficient for the electropenguin operator is re-analyzed within the four-flavor effective Hamiltonian. The ratio Γ(K⁺ → π⁺e⁺e⁻)/Γ(K⁺ → π⁰e⁺ν_e), the K_L → π⁰e⁺e⁻ decay rate and the ∆I = 1/2 rule in non-leptonic kaon decays are reconsidered by taking into account both the leading non-logarithmic contribution and the strong corrections in log (M_w/μ)² up to the next-to-leading order. Their dependence on the QCD parameters is studied and we argue that the inclusion of the strong corrections of order log (m_g/μ)² cannot be neglected.

When studying thermodynamic properties by means of quantum field theory methods one can deform the Matsubara integration contour in the complex time plane. The deformations are restricted by Hamiltonian singularities which are due to turning on an interaction. One should construct the real-time technique in the true vacuum taking the interaction into account.

We discuss the ultraviolet behavior of the non-unitary M_3/q (q = 5, 7) minimal models perturbed by the operator ϕ₁₃. The Thermodynamic Bethe Ansatz is used to compute the central charge and the next higher order corrections in the high temperature expansion of the finite volume ground state energy. The results are in perfect agreement with perturbative calculations. Generalizations of these results are commented on.