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H. Dehnen

Publications and source records attributed to H. Dehnen.

26 records · Page 2Linked to original sources
arXiv2002

General solutions for flat Friedmann universe filled by perfect fluid and scalar field with exponential potential

We study integrability by quadrature of a spatially flat Friedmann model containing both a minimally coupled scalar field $ϕ$ with an exponential potential $V(ϕ)\sim\exp[-\sqrt{6}σκϕ]$, $κ=\sqrt{8πG_N}$, of arbitrary sign and a perfect fluid with barotropic equation of state $p=(1-h)ρ$. From the mathematical view point the model is pseudo-Euclidean Toda-like system with 2 degrees of freedom. We apply the methods developed in our previous papers, based on the Minkowsky-like geometry for 2 characteristic vectors depending on the parameters $σ$ and $h$. In general case the problem is reduced to integrability of a second order ordinary differential equation known as the generalized Emden-Fowler equation, which was investigated by discrete-group methods. We present 4 classes of general solutions for the parameters obeying the following relations: {\bf A}. $σ$ is arbitrary, $h=0$; {\bf B}. $σ=1-h/2$, $0<h<2$; {\bf C1}. $σ=1-h/4$, $0<h\leq 2$; {\bf C2}. $σ=|1-h|$, $0<h\leq 2$, $h\neq 1,4/3$. We discuss the properties of the exact solutions near the initial singularity and at the final stage of evolution.

gr-qc↗
arXiv2002

On black hole solutions in model with anisotropic fluid

A family of spherically symmetric solutions in the model with 1-component anisotropic fluid is considered. The metric of the solution depends on a parameter q > 0 relating radial pressure and the density and contains n -1 parameters corresponding to Ricci-flat ``internal space'' metrics. For q = 1 and certain equations of state the metric coincides with the metric of black brane solutions in the model with antisymmetric form. A family of black hole solutions corresponding to natural numbers q = 1,2, ... is singled out. Certain examples of solutions (e.g. containing for q =1 Reissner-Nordström, M2 and M5 black brane metrics) are considered. The post-Newtonian parameters beta and gamma corresponding to the 4-dimensional section of the metric are calculated.

gr-qc↗
arXiv1998

Higgs Field and Localization Problem

We analyze the role that the excited states of the Higgs field could play in a possible solution to the so called localization problem of Quantum Theory. We seek a solution to the aforementioned point without introducing additional fundamental constants or extra hypotheses, as has been done in previous works. The electron and Higgs field do indeed have solitonic solutions. This last feature renders, in the one-dimensional case, a solution to the localization problem.

quant-ph↗
arXiv1997

Gravity and Parity Violation in Spin Gauge Theory

Within a spin-gauge theory of gravity unified with the electroweak interaction we start with totally symmetric left- and right-handed fermions and explain the parity violation by symmetry breaking in such a way that the $W^{\pm}$-bosons couple only to the left-handed leptons. Right-handed neutrinos exist and couple as the right-handed electrons only to the Z-bosons (and to gravity). The mass of the neutrinos comes out to be necessarily zero. Therefore this procedure cannot be transferred to the quarks, because then the u-quark would become massless too; for this reason parity violation with respect to the quarks is avoided. On the other hand concerning gravity the u-quark couples only with u-quarks and the d-quark only with d-quarks, however with the same strength, so that isotopic effects appear regarding the equivalence principle in such a way, that the macroscopic gravitational constant depends on the isotopic composition of the material.

gr-qc↗
arXiv1995

Induced gravity inflation in the standard model of particle physics

We are considering the cosmological consequences of an induced gravity theory coupled to the minimal standard model of particle physics. The non-minimal coupling parameter between gravity and the Higgs field must then be very large, yielding some new cosmological consequences for the early Universe and new constraints on the Higgs mass. As an outcome, new inflation is only possible for very special initial conditions producing first a short contraction era after which an inflationary expansion automatically follows; a chaotic inflationary scenario is successfully achieved. The contrast of density perturbations required to explain the seed of astronomic structures are obtained for very large values of the Higgs mass ($M_{H} >> G_{F}^{-1/2}$), otherwise the perturbations have a small amplitude; in any case, the spectral index of scalar perturbations agrees with the observed one.

astro-ph↗
arXiv1994

SU(2) $\times$ U(1) Gauge Gravity

We propose a Lorentz-covariant Yang-Mills ``spin-gauge'' theory, where the function valued Pauli matrices play the role of a non-scalar Higgs-field. As symmetry group we choose $SU(2) \times U(1)$ of the 2-spinors describing particle/antiparticle states. After symmetry breaking a non-scalar Lorentz-covariant Higgs-field gravity appears, which can be interpreted within a classical limit as Einstein's metrical theory of gravity, where we restrict ourselves in a first step to its linearized version.

gr-qc↗
arXiv1994

Induced gravity inflation in the SU(5) GUT

We investigate the cosmological consequences of a theory of induced gravity in which the scalar field is identified with the Higgs field of the first symmetry breaking of a mi\-ni\-mal SU(5) GUT. The mass of the X-boson determines a great value for the coupling constant of gravity-particle physics. Because of this fact, a "slow" rollover dynamics for the Higgs field is not possible in a "new" inflation scenario and, moreover, a contraction era for the scale factor in the early universe exists, \-after\- which inflation follows automatically; "chaotic" inflation is performed without problems. Inflation is successfully achieved due to the relationship among the masses of particle physics at that scale: The Higgs-, X-boson- and Planck-masses. As a result the particle physics pa\-ra\-me\-ter $λ$ is not fine-tuned as usual in order to predict acceptable values of re-heating temperature and density and gravitational wave perturbations. Moreover, if the coherent Higgs oscillations didn't decay they could explain the missing mass problem of cosmology.

astro-ph↗