18,153 research outputs found

    On geometric relativistic foundations of matter field equations and plane wave solutions

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    In this paper, we start from the geometric relativistic foundations to define the basis upon which matter field theories are built, and their wave solutions are investigated, finding that they display repulsive interactions able to reproduce the exclusion principle in terms of its effects in a dynamical way, then discussing possible consequences and problems.Comment: 11 page

    A torsional completion of gravity for Dirac matter fields and its applications to neutrino oscillations

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    In this paper, we consider the torsional completion of gravitation for an underlying background filled with Dirac fields, applying it to the problem of neutrino oscillations: we discuss the effects of the induced torsional interactions as corrections to the neutrino oscillation mechanism.Comment: 4 page

    Conformal Gravity with Electrodynamics for Fermion Fields and their Symmetry Breaking Mechanism

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    In this paper we consider an axial torsion to build metric-compatible connections in conformal gravity, with gauge potentials; the geometric background is filled with Dirac spinors: scalar fields with suitable potentials are added eventually. The system of field equations is worked out to have torsional effects converted into spinorial self-interactions: the massless spinors display self-interactions of a specific form that gives them the features they have in the non-conformal theory but with the additional character of renormalizability, and the mechanisms of generation of mass and cosmological constants become dynamical. As a final step we will address the cosmological constant and coincidence problems.Comment: 13 page

    Genus statistics on CMB polarization maps and cosmological parameters degeneracy

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    We applay the genus statistics to simulated CMB polarization maps, constructed from the secondary-ionization cosmological models in experimental situations comparable to those of forthcoming space experiments. We find that both the cosmic baryon density and the spectral index of density perturbations are strongly anicorrelated to the reionization redshift. Using the Fisher matrix approach we show that the accuracy on the spectral index and optical depth to the last scattering are improved in the case of genus statistics when comparing with the accuracy obtained from the standard power spectrum statistics.Comment: 22 pages in LaTex format, 4 figures in a single ps file Accepted at New Astronom

    Fourth derivative gravity in the auxiliary fields representation and application to the black hole stability

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    We consider an auxiliary fields formulation for the general fourth-order gravity on an arbitrary curved background. The case of a Ricci-flat background is elaborated in full details and it is shown that there is an equivalence with the standard metric formulation. At the same time, using auxiliary fields helps to make perturbations to look simpler and the results more clear. As an application we reconsider the linear perturbations for the classical Schwarzschild solution. We also briefly discuss the relation to the effect of massive unphysical ghosts in the theory.Comment: 11 pages, no figure

    Multi-band spectroscopy of inhomogeneous Mott-insulator states of ultracold bosons

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    In this work, we use inelastic scattering of light to study the response of inhomogeneous Mott-insulator gases to external excitations. The experimental setup and procedure to probe the atomic Mott states are presented in detail. We discuss the link between the energy absorbed by the gases and accessible experimental parameters as well as the linearity of the response to the scattering of light. We investigate the excitations of the system in multiple energy bands and a band-mapping technique allows us to identify band and momentum of the excited atoms. In addition the momentum distribution in the Mott states which is spread over the entire first Brillouin zone enables us to reconstruct the dispersion relation in the high energy bands using a single Bragg excitation with a fixed momentum transfer.Comment: 19 pages, 7 figure

    A Discussion on Dirac Field Theory, No-Go Theorems and Renormalizability

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    We study Dirac field equations coupled to electrodynamics with metric and torsion fields: we discuss how special spinorial solutions are incompatible with torsion; eventually these results will be used to sketch a discussion on the problem of renormalizability of point-like particles.Comment: 10 page

    Momentum-resolved study of an array of 1D strongly phase-fluctuating Bose gases

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    We investigate the coherence properties of an array of one-dimensional Bose gases with short-scale phase fluctuations. The momentum distribution is measured using Bragg spectroscopy and an effective coherence length of the whole ensemble is defined. In addition, we propose and demonstrate that time-of-flight absorption imaging can be used as a simple probe to directly measure the coherence-length of 1D gases in the regime where phase-fluctuations are strong. This method is suitable for future studies such as investigating the effect of disorder on the phase coherence.Comment: 4 pages, 4 figure
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