443 research outputs found
Crypto-baryonic Dark Matter
It is proposed that dark matter could consist of compressed collections of
atoms (or metallic matter) encapsulated into, for example, 20 cm big pieces of
a different phase. The idea is based on the assumption that there exists at
least one other phase of the vacuum degenerate with the usual one. Apart from
the degeneracy of the phases we only assume Standard Model physics. The other
phase has a Higgs VEV appreciably smaller than in the usual electroweak vacuum.
The balls making up the dark matter are very difficult to observe directly, but
inside dense stars may expand eating up the star and cause huge explosions
(gamma ray bursts). The ratio of dark matter to ordinary baryonic matter is
expressed as a ratio of nuclear binding energies and predicted to be about 5.Comment: 9 pages. Published version with shorter abstract and new referenc
Implementation of the Multiple Point Principle in the Two-Higgs Doublet Model of type II
The multiple point principle (MPP) is applied to the non--supersymmetric
two-Higgs doublet extension of the Standard Model (SM). The existence of a
large set of degenerate vacua at some high energy scale caused by the MPP
results in a few relations between Higgs self-coupling constants which can be
examined at future colliders. The numerical analysis reveals that these MPP
conditions constrain the mass of the SM--like Higgs boson to lie below 180 GeV
for a wide set of MPP scales and .Comment: 26 pages, 3 figures, some minor changes to the tex
Phase transition in gauge theories, monopoles and the Multiple Point Principle
This review is devoted to the Multiple Point Principle (MPP), according to
which several vacuum states with the same energy density exist in Nature. The
MPP is implemented to the Standard Model (SM), Family replicated gauge group
model (FRGGM) and phase transitions in gauge theories with/without monopoles.
Lattice gauge theories are reviewed. The lattice results for critical coupling
constants are compared with those of the Higgs Monopole Model (HMM), in which
the lattice artifact monopoles are replaced by the point-like Higgs scalar
particles with a magnetic charge. Considering our (3+1)-dimensional space-time
as discrete, for example, as a lattice with a parameter a=\lambda_P, equal to
the Planck length, we have investigated the additional contributions of
monopoles to beta-functions of renormalization group equations in the FRGGM
extended beyond the SM at high (the Planck scale) energies. We have reviewed
that, in contrast to the Anti-grand unified theory (AGUT), there exists a
possibility of unification of all gauge interactions (including gravity) near
the Planck scale due to monopoles. The unifications [SU(5)]^3 and [SO(10)]^3 at
the GUT-scale \sim 10^{18} GeV are briefly discussed.Comment: 100 pages, 25 figures, typos correcte
Approximate gauge symmetry of composite vector bosons
It can be shown in a solvable field theory model that the couplings of the
composite vector bosons made of a fermion pair approach the gauge couplings in
the limit of strong binding. Although this phenomenon may appear accidental and
special to the vector boson made of a fermion pair, we extend it to the case of
bosons being constituents and find that the same phenomenon occurs in more an
intriguing way. The functional formalism not only facilitates computation but
also provides us with a better insight into the generating mechanism of
approximate gauge symmetry, in particular, how the strong binding and global
current conservation conspire to generate such an approximate symmetry. Remarks
are made on its possible relevance or irrelevance to electroweak and higher
symmetries.Comment: Correction of typos. The published versio
Dicyclic Horizontal Symmetry and Supersymmetric Grand Unification
It is shown how to use as horizontal symmetry the dicyclic group in a supersymmetric unification where
one acts on the first and second families, in a horizontal doublet, and
the other acts on the third. This can lead to acceptable quark masses and
mixings, with an economic choice of matter supermultiplets, and charged lepton
masses can be accommodated.Comment: 10 pages, LaTe
Neutrino masses and flavor symmetries
The problem of neutrino masses and mixing angles is analysed in a class of
supersymmetric grand unified models, with SO(10) gauge symmetry and global U(2)
flavour symmetry. Adopting the seesaw mechanism for the generation of the
neutrino masses, one obtains a mass matrix for the left-handed neutrinos which
is directly related to the parameters of the charged sector, while the unknown
parameters of the right-handed Majorana mass matrix are inglobed in a single
factor.Comment: 17 pages, 1 eps figure, uses graphicx.sty, LaTeX 2e, to be published
on "Il Nuovo Cimento
Two-Higgs doublet models from TeV-scale supersymmetric extra U(1) models
We investigate the reduction of a general TeV-scale supersymmetric extra U(1)
model to a 2HDM below the TeV- scale through the tree level non-decoupling.
Portions of the parameter space of the extra U(1) model appropriate for
obtaining a 2HDM are identified. Various properties of the resulting 2HDM are
connected to the parameter space of the underlying model. PACS: 12.60.Jv,
12.60.Cn, 12.60.FrComment: 12 pages, 4 postscript figures, to appear in Phys. Rev.
An astronomical search for evidence of new physics: Limits on gravity-induced birefringence from the magnetic white dwarf RE J0317-853
The coupling of the electromagnetic field directly with gravitational gauge
fields leads to new physical effects that can be tested using astronomical
data. Here we consider a particular case for closer scrutiny, a specific
nonminimal coupling of torsion to electromagnetism, which enters into a
metric-affine geometry of space-time. We show that under the assumption of this
nonminimal coupling, spacetime is birefringent in the presence of such a
gravitational field. This leads to the depolarization of light emitted from
extended astrophysical sources. We use polarimetric data of the magnetic white
dwarf to set strong constraints on the essential coupling
constant for this effect, giving k^2 \lsim (19 {m})^2 .Comment: Statements about Moffat's NGT modified. Accepted for publication in
Phys.Rev.
Cosmological constant in SUGRA models and the multiple point principle
The tiny order of magnitude of the cosmological constant is sought to be
explained in a model involving the following ingredients: supersymmetry
breaking in N=1 supergravity and the multiple point principle. We demonstrate
the viability of this scenario in the minimal SUGRA model.Comment: 18 pages, 2 figures, Talk given at Nuclear Physics Department of the
Russian Academy of Sciences (RAS) Conference on Physics of Fundamental
Interactions, Moscow, Russia, 2-6 Dec 2002; to appear in Phys.Atom.Nuc
Re-identification of c. 15 700 cal yr BP tephra bed at Kaipo Bog, eastern North Island: implications for dispersal of Rotorua and Puketarata tephra beds.
A 10 mm thick, c. 15 700 calendar yr BP (c. 13 100 14C yr BP) rhyolitic tephra bed in the well-studied montane Kaipo Bog sequence of eastern North Island was previously correlated with Maroa-derived Puketarata Tephra. We revise this correlation to Okataina-derived Rotorua Tephra based on new compositional data from biotite phenocrysts and glass. The new correlation limits the known dispersal of Puketarata Tephra (sensu stricto, c. 16 800 cal yr BP) and eliminates requirements to either reassess its age or to invoke dual Puketarata eruptive events. Our data show that Rotorua Tephra comprises two glass-shard types: an early-erupted low-K2O type that was dispersed mostly to the northwest, and a high-K2O type dispersed mostly to the south and southeast, contemporary with late-stage lava extrusion. Late-stage Rotorua eruptives contain biotite that is enriched in FeO compared with biotite from Puketarata pyroclastics. The occurrence of Rotorua Tephra in Kaipo Bog (100 km from the source) substantially extends its known distribution to the southeast. Our analyses demonstrate that unrecognised syn-eruption compositional and dispersal changes can cause errors in fingerprinting tephra deposits. However, the compositional complexity, once recognised, provides additional fingerprinting criteria, and also documents magmatic and dispersal processes
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