221,360 research outputs found
Minimal metagravity vs. dark matter and/or dark energy
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
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
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
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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