221,360 research outputs found

    Minimal metagravity vs. dark matter and/or dark energy

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    The minimal metagravity theory, explicitly violating the general covariance but preserving the unimodular one, is applied to study the evolution of the isotropic homogeneous Universe. The massive scalar graviton, contained in the theory in addition to the massless tensor one, is treated as a source of the dark matter and/or dark energy. The modified Friedmann equation for the scale factor of the Universe is derived. The question wether the minimal metagravity can emulate the LCDM concordance model, valid in General Relativity, is discussed.Comment: 6 pages, a typo correcte

    Parameter counting for neutrino mixing

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    The content of physical massess, mixing angles and CP-violating phases in the lepton sector of extended standard model, both renormalizable and non-renormalizable, with arbitrary numbers of the singlet and left-handed doublet neutrinos is systematically analyzed in the weak basis.Comment: 11 pages, LaTe

    Emergent gravity, violated relativity and dark matter

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    The nonlinear affine Goldstone model of the emergent gravity, built on the nonlinearly realized/hidden affine symmetry, is concisely revisited. Beyond General Relativity, the explicit violation of general invariance/relativity, under preserving general covariance, is exposed. Dependent on a nondynamical affine connection, a generally covariant second-order effective Lagrangian for metric gravity is worked out, with the general relativity violation and the gravitational dark matter serving as the signatures of emergence.Comment: 10 pages, minor improvement

    Scalar graviton and the modified black holes

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    Under the explicit violation of the general covariance to the unimodular one, the effect of the emerging scalar graviton on the static spherically symmetric metrics is studied. The main results are three-fold. First, there appears the two-parametric family of such metrics, instead of the one-parametric black-hole family in General Relativity (GR). Second, there may exist the one-parametric subfamily describing a pure gravitational object, the ``graviball'', missing in GR. Third, in a simplifying assumption, all the metrics possess the correct Newton's limit as in GR.Comment: 9 pages, typos correcte
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