1,324 research outputs found
Baryogenesis in Lorentz-violating gravity theories
Lorentz-violating theories of gravity typically contain constrained vector
fields. We show that the lowest-order coupling of such vectors to
-symmetric scalars can naturally give rise to baryogenesis in a
manner akin to the Affleck-Dine mechanism. We calculate the cosmology of this
new mechanism, demonstrating that a net can be generated in the early
Universe, and that the resulting baryon-to-photon ratio matches that which is
presently observed. We discuss constraints on the model using solar system and
astrophysical tests of Lorentz violation in the gravity sector. Generic
Lorentz-violating theories can give rise to the observed matter-antimatter
asymmetry without violating any current bounds.Comment: Five pages, two figures, submitted to PL
Inflationary power asymmetry from primordial domain walls
We study the asymmetric primordial fluctuations in a model of inflation in
which translational invariance is broken by a domain wall. We calculate the
corrections to the power spectrum of curvature perturbations; they are
anisotropic and contain dipole, quadrupole, and higher multipoles with
non-trivial scale-dependent amplitudes. Inspired by observations of these
multipole asymmetries in terms of two-point correlations and variance in real
space, we demonstrate that this model can explain the observed anomalous power
asymmetry of the cosmic microwave background (CMB) sky, including its
characteristic feature that the dipole dominates over higher multipoles. We
test the viability of the model and place approximate constraints on its
parameters by using observational values of dipole, quadrupole, and octopole
amplitudes of the asymmetry measured by a local-variance estimator. We find
that a configuration of the model in which the CMB sphere does not intersect
the domain wall during inflation provides a good fit to the data. We further
derive analytic expressions for the corrections to the CMB temperature
covariance matrix, or angular power spectra, which can be used in future
statistical analysis of the model in spherical harmonic space.Comment: 22 pages, 7 figures. Version published in JCA
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