123206975
Neutrino Oscillations in the Robertson-Walker Metric and the Cosmological Blue Shift of the Oscillation Length
The Doppler effect of the neutrino oscillation length in the flat space is discussed. When the observer travels away from the source, the oscillation length decreases. Moreover, the mass neutrino oscillation in the Robertson-Walker metric is studied, and the general equations of the oscillation phases are given. We obtain the relation between the phase and the scale factor. The expansion of the universe leads to the reduction of the oscillation length (blue shift), which is contrary to the red shift of the light ray.
122941988
Neutrino Oscillations in the de Sitter and the Anti-de Sitter Space-Time
General expressions of the neutrino oscillation phase in the generally static space-time with spherical symmetry are given. The effect of the gravitational field on the oscillation length is embodied in the gravitational red shift factor. We find that a blue shift of the oscillation length takes place when the neutrino travels out of the gravitational field. Then, we discuss the variation of the oscillation length influenced by the cosmological constant. In the de Sitter space-time, the positive cosmological constant prolongs the oscillation length. And, in the anti-de Sitter space-time, the negative cosmological constant shortens it as expected.
125003050
Particle tunnels from Garfinkle-Horne black hole and Horowitz-Strominger black hole
When the black hole radiates particles, it losses energy and shrinks, it is the contraction of the horizon that sets the tunnelling barrier. This article extents the work of M. Parikh to GH black hole and HS black hole. Applying WKB approximation, we calculate the rate of Hawking radiation and found that the rate of tunnelling equals precisely the exponent of the difference of the entropy of the black hole before and after emission. We also obtain the result that the energy spectrum of radiation deviates from the exact thermality.
55815188
Probing Gravitational Dark Matter
So far all evidences of dark matter (DM) come from astrophysical and cosmological observations, due to gravitational interactions of the DM. It is possible that the true DM particle in the universe joins gravitational interactions only, but nothing else. Such a Gravitational DM (GDM) may act as a weakly interacting massive particle (WIMP), which is conceptually simple and attractive. In this work, we explore this direction by constructing the simplest scalar GDM particle s . It is a Z 2 odd singlet under the standard model (SM) gauge group, and naturally joins the unique dimension-4 interaction with Ricci curvature, s 2 R , where s is the dimensionless nonminimal coupling. We demonstrate that this gravitational interaction s 2 R , together with Higgs-curvature nonminimal coupling term h H y HR , induces eective couplings between 2 and SM elds, and can account for the observed DM thermal relic abundance. We analyze the annihilation cross sections of GDM particles and derive the viable parameter space for realizing the DM thermal relic density. We further study the direct/indirect detections and the collider signatures of such a scalar GDM. These turn out to be highly predictive and testable.
119215169
Constraints on the Scalar Sector of the Renormalizable Coloron Model
The renormalizable coloron model is the minimal extension of the standard model color sector, in which the color gauge group is enlarged to SU(3)_{1c} x SU(3)_{2c}. In this paper we discuss the constraints on this model derived from the requirements of vacuum stability, tree-level unitarity, electroweak precision measurements, and from LHC measurements of the properties of the observed Higgs-like scalar boson. The combination of these theoretical and experimental considerations strongly constrains the allowed parameter space. (Erratum appended, March 2014.)
54201703
Higgs gravitational interaction, weak boson scattering, and Higgs inflation in Jordan and Einstein frames
We study gravitational interaction of Higgs boson through the unique dimension-4 operator xi(HHR)-H-dagger, with H the Higgs doublet and R the Ricci scalar curvature. We analyze the effect of this dimensionless nonminimal coupling xi on weak gauge boson scattering in both Jordan and Einstein frames. We explicitly establish the longitudinal-Goldstone equivalence theorem with nonzero xi coupling in both frames, and analyze the unitarity constraints. We study the xi-induced weak boson scattering cross sections at O(1 30) TeV scales, and propose to probe the Higgs-gravity coupling via weak boson scattering experiments at the LHC (14 TeV) and the next generation pp colliders (50 100 TeV). We further extend our study to Higgs inflation, and quantitatively derive the perturbative unitarity bounds via coupled channel analysis, under large field background at the inflation scale. We analyze the unitarity constraints on the parameter space in both the conventional Higgs inflation and the improved models in light of the recent BICEP2 data.
119368144
DARK VISCOUS FLUID DESCRIBED BY A UNIFIED EQUATION OF STATE IN COSMOLOGY
We generalize the ΛCDM model by introducing a unified EOS to describe the Universe contents modeled as dark viscous fluid, motivated by the fact that a single constant equation of state (EOS) p = -p0 (p0 > 0) reproduces the ΛCDM model exactly. This EOS describes the perfect fluid term, the dissipative effect, and the cosmological constant in a unique framework and the Friedmann equations can be analytically solved. Especially, we find a relation between the EOS parameter and the renormalizable condition of a scalar field. We develop a completely numerical method to perform a χ2 minimization to constrain the parameters in a cosmological model directly from the Friedmann equations, and employ the SNe data with the parameter $\mathcal{A}$ measured from the SDSS data to constrain our model. The result indicates that the dissipative effect is rather small in the late-time Universe.
119515694
Friedmann cosmology with a generalized equation of state and bulk viscosity
The universe media is considered as a non-perfect fluid with bulk viscosity and described by a more general equation of state. We assume the bulk viscosity is a linear combination of the two terms: one is constant, and the other is proportional to the scalar expansion $\theta=3\dot{a}/a$. The equation of state is described as $p=(\gamma-1)\rho+p_0$, where $p_0$ is a parameter. This model can be used to explain the dark energy dominated universe. Different choices of the parameters may lead to three kinds of fates of the cosmological evolution: no future singularity, big rip, or Type III singularity of Ref. [S. Nojiri, S.D. Odintsov, and S. Tsujikawa, Phys. Rev. D \textbf{71}, 063004 (2005)].