Estimates of Radiation by Superluminal Neutrinos

We show that the more energetic superluminal neutrinos with quadratically dispersed superluminalities \delta=\beta^2-1, for \beta=v/c where v is the neutrino velocity, also lose significant energy to radiation to the \nu+e^-+e^+ final state in travelling from CERN to Gran Sasso as has been shown to occur for those with constant superluminality by Cohen and Glashow if indeed \delta \simeq 5\times 10^{-5}. In addition, we clarify the dependence of such radiative processes on the size of the superluminality.Comment: 6 pages, no figures; text re-arranged for journal purposes; improved references; published version(title changed by Editors

Extremal Black Attractors in 8D Maximal Supergravity

Motivated by the new higher D-supergravity solutions on intersecting attractors obtained by Ferrara et al. in [Phys.Rev.D79:065031-2009], we focus in this paper on 8D maximal supergravity with moduli space [SL(3,R)/SO(3)]x[SL(2,R)/SO(2)] and study explicitly the attractor mechanism for various configurations of extremal black p- branes (anti-branes) with the typical near horizon geometries AdS_{p+2}xS^{m}xT^{6-p-m} and p=0,1,2,3,4; 2<=m<=6. Interpretations in terms of wrapped M2 and M5 branes of the 11D M-theory on 3-torus are also given. Keywords: 8D supergravity, black p-branes, attractor mechanism, M-theory.Comment: 37 page

Phase Transition in Asymmetrical Superfluids I: Equal Fermi Surfaces

In this paper, we study phase transitions in asymmetrical fermion superfluids. In this scenario, the candidates to form pair are particles with mismatched masses and chemical potentials. We derive an expression for the critical temperature in terms of the gap and masses (or chemical potentials) when the constraint of equal Fermi surfaces $m_a\mu_a = m_b\mu_b$ is imposed.Comment: RevTex, 11 pages, 2 figures, typos corrected and an appendix added, accepted for publication in Phys. Rev.

Omega and Eta (Eta-prime) mesons from NN and ND collisions at intermediate energies

The production of pseudo scalar, Eeta, Eta-prime, and vector, Omega, Rho, Phi, mesons in NN collisions at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. It is shown that a good description of cross sections and angular distributions, for vector meson production, can be accomplished by considering meson and nucleon currents only, while for pseudo scalar production an inclusion of nucleon resonances is needed. The di-electron production from subsequent Dalitz decay of the produced mesons, $\eta'\to \gamma \gamma^* \to\gamma e^+e^-$ and $\omega\to \pi\gamma^*\to \pi e^+e^-$ is also considered and numerical results are presented for intermediate energies and kinematics of possible experiments with HADES, CLAS and KEK-PS. We argue that the transition form factor $\omega\to \gamma^*\pi$ as well as $\eta'\to \gamma^*\gamma$ can be defined in a fairly model independent way and the feasibility of an experimental access to transition form factors is discussed.Comment: Presented at the International Conference on Nuclear Reactions on Nucleons and Nuclei, Oct. 5-10, 2009, Messina, Ital

Non-Abelian gauge field theory in scale relativity

Gauge field theory is developed in the framework of scale relativity. In this theory, space-time is described as a non-differentiable continuum, which implies it is fractal, i.e., explicitly dependent on internal scale variables. Owing to the principle of relativity that has been extended to scales, these scale variables can themselves become functions of the space-time coordinates. Therefore, a coupling is expected between displacements in the fractal space-time and the transformations of these scale variables. In previous works, an Abelian gauge theory (electromagnetism) has been derived as a consequence of this coupling for global dilations and/or contractions. We consider here more general transformations of the scale variables by taking into account separate dilations for each of them, which yield non-Abelian gauge theories. We identify these transformations with the usual gauge transformations. The gauge fields naturally appear as a new geometric contribution to the total variation of the action involving these scale variables, while the gauge charges emerge as the generators of the scale transformation group. A generalized action is identified with the scale-relativistic invariant. The gauge charges are the conservative quantities, conjugates of the scale variables through the action, which find their origin in the symmetries of the ``scale-space''. We thus found in a geometric way and recover the expression for the covariant derivative of gauge theory. Adding the requirement that under the scale transformations the fermion multiplets and the boson fields transform such that the derived Lagrangian remains invariant, we obtain gauge theories as a consequence of scale symmetries issued from a geometric space-time description.Comment: 24 pages, LaTe

Neutrino-nucleus interactions at low energies within Fermi-liquid theory

Cross sections are calculated for neutrino scattering off heavy nuclei at energies below 50 MeV. The theory of Fermi liquid is applied to estimate the rate of neutrino-nucleon elastic and inelastic scattering in a nuclear medium in terms of dynamic form factors. The cross sections, obtained here in a rather simple way, are in agreement with the results of the other much more sophisticated nuclear models. A background rate from the solar neutrino interactions within a large Ge detector is estimated in the above-mentioned approach. The knowledge of the rate is in particular rather important for new-generation large-scale neutrino experiments.Comment: 9 pages, 6 figure

Series solutions for a static scalar potential in a Salam-Sezgin Supergravitational hybrid braneworld

The static potential for a massless scalar field shares the essential features of the scalar gravitational mode in a tensorial perturbation analysis about the background solution. Using the fluxbrane construction of [8] we calculate the lowest order of the static potential of a massless scalar field on a thin brane using series solutions to the scalar field's Klein Gordon equation and we find that it has the same form as Newton's Law of Gravity. We claim our method will in general provide a quick and useful check that one may use to see if their model will recover Newton's Law to lowest order on the brane.Comment: 5 pages, no figure

Gedanken Worlds without Higgs: QCD-Induced Electroweak Symmetry Breaking

To illuminate how electroweak symmetry breaking shapes the physical world, we investigate toy models in which no Higgs fields or other constructs are introduced to induce spontaneous symmetry breaking. Two models incorporate the standard SU(3)_c x SU(2)_L x U(1)_Y gauge symmetry and fermion content similar to that of the standard model. The first class--like the standard electroweak theory--contains no bare mass terms, so the spontaneous breaking of chiral symmetry within quantum chromodynamics is the only source of electroweak symmetry breaking. The second class adds bare fermion masses sufficiently small that QCD remains the dominant source of electroweak symmetry breaking and the model can serve as a well-behaved low-energy effective field theory to energies somewhat above the hadronic scale. A third class of models is based on the left-right--symmetric SU(3)_c x SU(2)_L x SU(2)_R x U(1)_{B-L} gauge group. In a fourth class of models, built on SU(4)_{PS} x SU(2)_L x SU(2)_R gauge symmetry, lepton number is treated as a fourth color. Many interesting characteristics of the models stem from the fact that the effective strength of the weak interactions is much closer to that of the residual strong interactions than in the real world. The Higgs-free models not only provide informative contrasts to the real world, but also lead us to consider intriguing issues in the application of field theory to the real world.Comment: 20 pages, no figures, uses RevTeX; typos correcte

No-scale D=5 supergravity from Scherk-Schwarz reduction of D=6 theories

We perform a generalized dimensional reduction of six dimensional supergravity theories to five dimensions. We consider the minimal $(2,0)$ and the maximal $(4,4)$ theories. In each case the reduction allows us to obtain gauged supergravities of no-scale type in dimension five with gauge groups that escape previous classifications. In the minimal case, the geometric data of the reduced theory correspond to particular cases of the D=5 real special geometry. In the maximal case we find a four parameter solution which allows partial breaking of supersymmetry.Comment: AMS-LaTeX 16 pages. A reference added, some minor changes performe