119057266
Equation of State for Neutralino Star as a Form of Cold Dark Matter
In order to study the structure of neutralino star and dark galaxy, we consider dynamical interactions due to boson-exchange in the neutralino matter. Taking into account interactions of neutralinos with bosons, we derive the equation of state (EOS) of neutralino stars in terms of the relativistic mean field approach. Then we apply the resulting EOS to investigate properties of the neutralino star such as its density profile and mass limit. For example, if the neutralino mass is around 1 TeV, the Oppenheimer mass limit of the neutralino star is obtained as $6.06\times 10^{-7}M_\odot$, and the corresponding radius is about 7.8 mm. Actually, due to an increasing annihilation rate as indicated by our calculation, this dense state can never be realized in practice. Our results also show that the low density neutralino star may be a possible aggregation of the cold dark matter.
119356187
Cosmological model with viscosity media (dark fluid) described by an effective equation of state
Abstract A generally parameterized equation of state (EOS) is investigated in the cosmological evolution with bulk viscosity media modelled as dark fluid, which can be regarded as a unification of dark energy and dark matter. Compared with the case of the perfect fluid, this EOS has possessed four additional parameters, which can be interpreted as the case of the non-perfect fluid with time-dependent viscosity or the model with variable cosmological constant. From this general EOS, a completely integrable dynamical equation to the scale factor is obtained with its solution explicitly given out. (i) In this parameterized model of cosmology, for a special choice of the parameters we can explain the late-time accelerating expansion universe in a new view. The early inflation, the median (relatively late time) deceleration, and the recently cosmic acceleration may be unified in a single equation. (ii) A generalized relation of the Hubble parameter scaling with the redshift is obtained for some cosmology interests. (iii) By using the SNe Ia data to fit the effective viscosity model we show that the case of matter described by p = 0 plus with effective viscosity contributions can fit the observational gold data in an acceptable level.
119485377
Modified equation of state, scalar field, and bulk viscosity in Friedmann universe
Abstract A generalized dynamical equation for the scale factor of the universe is proposed to describe the cosmological evolution, of which the ΛCDM model is a special case. It also provides a general example to show the equivalence of the modified equation of state (EOS) and a scalar field model. In the mathematical aspect, the EOS, the scalar field potential V ( φ ) , and the scale factor a ( t ) all have possessed analytical solutions. Such features are due to a simple form invariance of the equation inherited which determines the Hubble parameter. From the physical point of view, this dynamical equation can be regarded as the ΛCDM model with bulk viscosity, an existence content in the universe. We employ the SNe Ia data with the parameter A measured from the SDSS data and the shift parameter R measured from WMAP data to constrain the parameters in our model. The result is that the contribution of the bulk viscosity, accumulated as an effective dark energy responsible for the current cosmic accelerating expansion, is made approximately ten percent to that of the cosmological constant.
119190318
Analytic fermionic Green’s functions from holography
We find exact, analytic solutions of the Dirac equation for a charged, massless fermion in the background of a charged, dilatonic black hole in AdS_5. The black hole descends from type IIB supergravity, where it describes D3-branes with equal angular momenta in two of the three independent planes of rotation orthogonal to the world-volume. The Green's function near the Fermi surface for a strongly coupled fermionic system can be extracted holographically from an exact solution of the Dirac equation at zero frequency but nonzero momentum. There can be several Fermi momenta, and they take the form k_F=q-n-1/2 (in units of the chemical potential), where q is the charge of the spinor, and n is a non-negative integer that labels the Fermi surfaces. Much as for holographic Fermi surfaces based on the Reissner-Nordstrom-AdS_5 solution, the dispersion relation of the excitations near the Fermi surface is determined by the geometry close to the horizon, and one can obtain Fermi liquid, marginal Fermi liquid, and non-Fermi liquid behaviors depending on the value of k_F.
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)].
118756844
Observe the open universe in the sky
We first review the related works on the observable consequence of landscape and the regulation of e-foldings during inflation. We focus on a branch of observable consequence of landscape which predicts an open universe with negative curvature if e-foldings $N>62$. After discussing the observable regulation from the aspect by Kaloper, Kleban and Sorbo, we make an argument that in the non-flat background the observable $N$ is suppressed by a factor $k/\rho_{0}$. We point out that this seems to detect the information where e-foldings $N>62$ possibly. Finally, we discuss our outcomes with the recent work by Arkani-Hamed et al.
119298728
Gravitational Interaction of Higgs Boson and Weak Boson Scattering
With the LHC discovery of a 125 GeV Higgs-like boson, we study the gravitational interaction of the Higgs boson via the unique dimension-four operator involving the Higgs doublet and scalar curvature, xi HyHR, with nonminimal coupling xi. This Higgs portal term can be transformed away in the Einstein frame and induces gauge-invariant effective interactions in the Higgs sector. We study the weak boson scattering in the Einstein frame and explicitly demonstrate the longitudinal-Goldstone boson equivalence theorem in the presence of xi coupling. With these, we derive a perturbative unitarity bound on the Higgs gravitational coupling xi in the Einstein frame, which is stronger than that inferred from the LHC Higgs measurements. We further study xi -dependent weak boson scattering cross sections at the TeV scale and propose a new LHC probe of Higgs-gravity coupling xi via weak boson scattering experiments.
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.
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.
118671365
Technipion Limits from LHC Higgs Searches
LHC searches for the standard model Higgs Boson in di-photon or di-tau decay modes place strong constraints on the light top-pion state predicted in technicolor models that include colored technifermions. Compared with the standard Higgs Boson, the top-pions have an enhanced production rate (largely because the technipion decay constant is smaller than the weak scale) and also enhanced branching ratios into di-photon and di-tau final states (largely due to the suppression of WW decays of the technipions). These factors combine to make the technipions more visible in both channels than a standard model Higgs would be. Hence, the recent ATLAS and CMS searches for Higgs bosons exclude the presence of technipions with masses from 110 GeV to nearly twice the top-quark mass in technicolor models that (a) include colored technifermions (b) feature topcolor dynamics and (c) have technicolor groups with three or more technicolors. For certain models, the limits also apply out to higher technipion masses or down to the minimum number of technicolors. The limits may be softened somewhat in models where extended technicolor plays a significant role in producing the top quark's mass. Additional LHC data on di-tau and di-photon final states will be extremely valuable in further exploring technicolor parameter space.
55805244
LHC constraints on a Higgs boson partner from an extended color sector
the presence of a heavy Higgs and to the detailed properties of the 125 GeV Higgs will further constrain the properties of the new heavy s scalar. Since the renormalizable coloron model may contain spectator fermions to remove anomalies, we examine several representative scenarios with different numbers of spectator fermions. Our results are summarized in plots that overlay the current exclusion limits on the s boson with the projected sensitivity of the ffiffiffi s p ¼ 14TeV LHC to the new state. We find that the upcoming LHC searches should be sensitive to an s scalar of mass less than 1 TeV for essentially all of the model parameter space in which the h state differs from the Higgs boson of the SM. More precisely, unless the mixing between the weak doublet and weak singlet gauge-eigenstate scalars is zero, the 14 TeV LHC will be sensitive to the presence of the nonstandard heavy s state that is characteristic of the renormalizable coloron model.