105 research outputs found
Non-Abelian black holes: The inside story
Recent progress in understanding of the internal structure of non-Abelian
black holes is discussed.
Talk given at the international Workshop on The Internal Structure of Black
Holes and Spacetime Singularities, Haifa, Israel, June 29 -- July 3, 1997.Comment: 23 pages, latex, contains 12 eps files combined in 8 figure
Scalar Lumps with Two Horizons
We study generalisations of the Schwarzschild-de Sitter solution in the presence of a scalar field with a potential barrier. These static, spherically symmetric solutions have two horizons, in between which the scalar interpolates at least once across the potential barrier, thus developing a lump. In part, we recover solutions discussed earlier in the literature and for those we clarify their properties. But we also find a new class of solutions in which the scalar lump curves the spacetime sufficiently strongly so as to change the nature of the erstwhile cosmological horizon into an additional trapped horizon, resulting in a scalar lump surrounded by two black holes. These new solutions appear in a wide range of the parameter space of the potential. We also discuss (challenges for) the application of all of these solutions to black hole seeded vacuum decay
Dihedral Families of Quarks, Leptons and Higgs Bosons
We consider finite groups of small order for family symmetry. It is found
that the binary dihedral group Q_6, along with the assumption that the Higgs
sector is of type II, predicts mass matrix of a nearest neighbor interaction
type for quarks and leptons. We present a supersymmetric model based on Q_6
with spontaneously induced CP phases. The quark sector contains 8 real
parameters with one independent phase to describe the quark masses and their
mixing. Predictions in the |V_{ub}|-bar{eta}, |V_{ub}|-sin 2 beta(phi_1) and
|V_{ub}|-|V_{td}/V_{ts}| planes are given. The lepton sector contains also 9
parameters. A normal as well as an inverted spectrum of neutrino masses is
possible, and we compute V_{e3}. We find that |V_{e3}|^2 > 10^{-4} in the case
of a normal spectrum, and |V_{e3}|^2 >8 10^{-4} in the case of an inverted
spectrum. It is also found that Q_6 symmetry forbids all Baryon number
violating terms of d=4, and the contributions to EDMs from the A terms vanish
in this model.Comment: 27 pages, 8 figure
Mass inflation inside non-Abelian black holes
The interior geometry of static, spherically symmetric black holes of the Einstein-Yang-Mills-Higgs theory is analyzed. It is found that in contrast to the Abelian case generically no inner (Cauchy) horizon is formed inside non-Abelian black holes. Instead the solutions come close to a Cauchy horizon but then undergo an enormous growth of the mass function, a phenomenon which can be termed `mass inflation' in analogy to what is observed for perturbations of the Reissner-Nordstr{ø}m solution. A significant difference between the theories with and without a Higgs field is observed. Without a Higgs field the YM field induces repeated cycles of mass inflation -- taking the form of violent `explosions' -- interrupted by quiescent periods and subsequent approaches to an almost Cauchy horizon. With the Higgs field no such cycles occur. Besides the generic solutions there are non-generic families with a Schwarzschild, Reissner-Nordstr{ø}m and a pseudo Reissner-Nordstr{ø}m type singularity at $r=0
Scalar lumps with a horizon
We study a self-interacting scalar field theory coupled to gravity and are interested in spherically symmetric solutions with a regular origin surrounded by a horizon. For a scalar potential containing a barrier, and using the most general spherically symmetric ansatz, we show that in addition to the known static, oscillating solutions discussed earlier in the literature there exist new classes of solutions which appear in the strong field case. For these solutions the spatial sphere shrinks either beyond the horizon, implying a collapsing universe outside of the cosmological horizon, or it shrinks already inside of the horizon, implying the existence of a black hole surrounding the scalar lump in all directions. Crucial for the existence of all such solutions is the presence of a scalar field potential with a barrier that satisfies the swampland conjectures
THE NUMBER OF SPHALERON INSTABILITIES OF THE BARTNIK-McKINNON SOLITONS AND NON-ABELIAN BLACK HOLES
It is proven that there are precisely odd-parity sphaleron-like unstable
modes of the -th Bartnik-McKinnon soliton and the -th non-abelian black
hole solution of the Einstein-Yang-Mills theory for the gauge group .Comment: one reference is adde
Light Sterile Neutrinos in the Supersymmetric U(1)' Models and Axion Models
We propose the minimal supersymmetric sterile neutrino model (MSSNM) where
the sterile neutrino masses are about 1 eV, while the active neutrino masses
and the mixings among the active and sterile neutrinos are generated during
late time phase transition. All the current experimental neutrino data include
the LSND can be explained simultaneously, and the constraints on the sterile
neutrinos from the big bang nucleosynthesis and large scale structure can be
evaded. To realize the MSSNM naturally, we consider the supersymmetric
intermediate-scale U(1)' model, the low energy U(1)' model with a secluded
U(1)'-breaking sector, and the DFSZ and KSVZ axion models. In these models, the
problem can be solved elegantly, and the 1 eV sterile neutrino masses can
be generated via high-dimensional operators. For the low energy U(1)' model
with a secluded U(1)'-breaking sector, we also present a scenario in which the
masses and mixings for the active and sterile neutrinos are all generated
during late time phase transition.Comment: RevTex4, 19 pages, References adde
Homogeneous Modes of Cosmological Instantons
We discuss the O(4) invariant perturbation modes of cosmological instantons.
These modes are spatially homogeneous in Lorentzian spacetime and thus not
relevant to density perturbations. But their properties are important in
establishing the meaning of the Euclidean path integral. If negative modes are
present, the Euclidean path integral is not well defined, but may nevertheless
be useful in an approximate description of the decay of an unstable state. When
gravitational dynamics is included, counting negative modes requires a careful
treatment of the conformal factor problem. We demonstrate that for an
appropriate choice of coordinate on phase space, the second order Euclidean
action is bounded below for normalized perturbations and has a finite number of
negative modes. We prove that there is a negative mode for many gravitational
instantons of the Hawking-Moss or Coleman-De Luccia type, and discuss the
associated spectral flow. We also investigate Hawking-Turok constrained
instantons, which occur in a generic inflationary model. Implementing the
regularization and constraint proposed by Kirklin, Turok and Wiseman, we find
that those instantons leading to substantial inflation do not possess negative
modes. Using an alternate regularization and constraint motivated by reduction
from five dimensions, we find a negative mode is present. These investigations
shed new light on the suitability of Euclidean quantum gravity as a potential
description of our universe.Comment: 16 pages, compressed and RevTex file, including one postscript figure
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