Supersymmetry breaking induced by radiative corrections

We show that simultaneous gauge and supersymmetry breaking can be induced by radiative corrections, a la Coleman-Weinberg. When a certain correlation among the superpotential parameters is present, a local supersymmetry-breaking minimum is found in the effective potential of a gauge non-singlet field, in a region where the tree-level potential is almost flat. Supersymmetry breaking is then transmitted to the MSSM through gauge and chiral messenger loops, thus avoiding the suppression of gaugino masses characteristic of direct gauge mediation models. The use of a single field ensures that no dangerous tachyonic scalar masses are generated at the one-loop level. We illustrate this mechanism with an explicit example based on an SU(5) model with a single adjoint. An interesting feature of the scenario is that the GUT scale is increased with respect to standard unification, thus allowing for a larger colour Higgs triplet mass, as preferred by the experimental lower bound on the proton lifetime.Comment: 22 pages, 3 figures. Two references added, small redactional changes, some discussion improved. Results unchange

Momentum Dependent Vertices σγγ\sigma \gamma \gamma, σργ\sigma \rho \gamma and σρρ\sigma \rho \rho : The NJL Scalar Hidden by Chiral Symmetry

We calculate the momentum dependence of three particle vertices $\sigma \gamma \gamma$, $\sigma \rho \gamma$ and $\sigma \rho \rho$ in the context of a Nambu Jona Lasinio type model. We show how they influence the processes $\gamma \gamma \rightarrow \sigma \rightarrow \pi \pi$, $\rho \rightarrow \gamma \sigma$ and $\gamma \gamma \rightarrow \rho \rho$ and how chiral symmetry shadows the presence of the $\sigma$.Comment: 9 pages (latex), 5 figures available from the authors, preprint Coimbra 940506, IJS-TP-94/10, accepted for publication in Zeit. f. Physik

The WW Boson Loop Background to H -> ZZ at Photon-photon Colliders

We have performed a complete one-loop calculation of $\gamma \gamma \rightarrow ZZ$ in the Standard Model, including both gauge bosons and fermions in the loop. We confirm the large irreducible continuum background from the $W$-boson loop found by Jikia. We have included the photon-photon luminosity, and find that the continuum background of transverse $Z$ boson pairs prohibits finding a heavy Higgs with mass \gtap 350 GeV in this decay mode.Comment: 16 pages + 4 PS figures included (uuencoded), MAD/PH/77

Localization of Matter Fields in the 5D Standing Wave Braneworld

We investigate the localization problem of matter fields within the 5D standing wave braneworld. In this model the brane emits anisotropic waves into the bulk with different amplitudes along different spatial dimensions. We show that in the case of increasing warp factor there exist the pure gravitational localization of all kinds of quantum and classical particles on the brane. For classical particles the anisotropy of the background metric is hidden, brane fields exhibit standard Lorentz symmetry in spite of anisotropic nature of the primordial 5D metric.Comment: The version accepted by JHE

Gravitating global monopoles in extra dimensions and the brane world concept

Multidimensional configurations with Minkowski external space-time and a spherical global monopole in extra dimensions are discussed in the context of the brane world concept. The monopole is formed with a hedgehog-like set of scalar fields \phi^i with a symmetry-breaking potential V depending on the magnitude \phi^2 = \phi^i \phi^i. All possible kinds of globally regular configurations are singled out without specifying the shape of V(\phi). These variants are governed by the maximum value \phi_m of the scalar field, characterizing the energy scale of symmetry breaking. If \phi_m < \phi_cr (where \phi_cr is a critical value of \phi related to the multidimensional Planck scale), the monopole reaches infinite radii while in the ``strong field regime'', when \phi_m\geq \phi_cr, the monopole may end with a cylinder of finite radius or possess two regular centers. The warp factors of monopoles with both infinite and finite radii may either exponentially grow or tend to finite constant values far from the center. All such configurations are shown to be able to trap test scalar matter, in striking contrast to RS2 type 5D models. The monopole structures obtained analytically are also found numerically for the Mexican hat potential with an additional parameter acting as a cosmological constant.Comment: 21 pages, 6 figures, latex, gc styl

Localization of Scalar Fluctuations in a Dilatonic Brane-World Scenario

We derive and solve the full set of scalar perturbation equations for a class of $Z_2$-symmetric five-dimensional geometries generated by a bulk cosmological constant and by a 3-brane non-minimally coupled to a bulk dilaton field. The massless scalar modes, like their tensor analogues, are localized on the brane, and provide long-range four-dimensional dilatonic interactions, which are generically present even when matter on the brane carries no dilatonic charge. The shorter-range corrections induced by the continuum of massive scalar modes are always present: they persist even in the case of a trivial dilaton background (the standard Randall--Sundrum configuration) and vanishing dilatonic charges.Comment: 22 pages, late

Limits on scalar leptoquark interactions and consequences for GUTs

A colored weak singlet scalar state with hypercharge 4/3 is one of the possible candidates for the explanation of the unexpectedly large forward-backward asymmetry in t tbar production as measured by the CDF and D0 experiments. We investigate the role of this state in a plethora of flavor changing neutral current processes and precision observables of down-quarks and charged leptons. Our analysis includes tree- and loop-level mediated observables in the K and B systems, the charged lepton sector, as well as the Z to b bbar decay width. We perform a global fit of the relevant scalar couplings. This approach can explain the (g-2)_mu anomaly while tensions among the CP violating observables in the quark sector, most notably the nonstandard CP phase (and width difference) in the Bs system cannot be fully relaxed. The results are interpreted in a class of grand unified models which allow for a light colored scalar with a mass below 1TeV. We find that the renormalizable SU(5) scenario is not compatible with our global fit, while in the SO(10) case the viability requires the presence of both the 126- and 120-dimensional representations.Comment: 26 pages, 7 figures; version as publishe

Minimal Supersymmetric Pati-Salam Theory: Determination of Physical Scales

We systematically study the minimal supersymmetric Pati-Salam theory, paying special attention to the unification constraints. We find that the SU(4)_c scale M_c and the Left-Right scale M_R lie in the range 10^{10} GeV < M_c < 10^{14} GeV, 10^{3} GeV < M_R <10^{10} GeV (with single-step breaking at 10^{10} GeV), giving a potentially accessible scale of parity breaking. The theory includes the possibility of having doubly-charged supermultiplets at the supersymmetry breaking scale; color octet states with mass of order M_R^2/M_c; magnetic monopoles of intermediate mass that do not conflict with cosmology, and a 'clean' (type I) form for the see-saw mechanism of neutrino mass.Comment: 5 page

Critical temperature for kaon condensation in color-flavor locked quark matter

We study the behavior of Goldstone bosons in color-flavor-locked (CFL) quark matter at nonzero temperature. Chiral symmetry breaking in this phase of cold and dense matter gives rise to pseudo-Goldstone bosons, the lightest of these being the charged and neutral kaons K^+ and K^0. At zero temperature, Bose-Einstein condensation of the kaons occurs. Since all fermions are gapped, this kaon condensed CFL phase can, for energies below the fermionic energy gap, be described by an effective theory for the bosonic modes. We use this effective theory to investigate the melting of the condensate: we determine the temperature-dependent kaon masses self-consistently using the two-particle irreducible effective action, and we compute the transition temperature for Bose-Einstein condensation. Our results are important for studies of transport properties of the kaon condensed CFL phase, such as bulk viscosity.Comment: 24 pages, 8 figures, v2: new section about effect of electric neutrality on critical temperature added; references added; version to appear in J.Phys.

Discriminating neutrino mass models using Type II seesaw formula

In this paper we propose a kind of natural selection which can discriminate the three possible neutrino mass models, namely the degenerate, inverted hierarchical and normal hierarchical models, using the framework of Type II seesaw formula. We arrive at a conclusion that the inverted hierarchical model appears to be most favourable whereas the normal hierarchical model follows next to it. The degenerate model is found to be most unfavourable. We use the hypothesis that those neutrino mass models in which Type I seesaw term dominates over the Type II left-handed Higgs triplet term are favoured to survive in nature.Comment: No change in the results, a few references added, some changes in Type[IIB] calculation