6,457 research outputs found
Cosmological Higgs fields
We present a time-dependent solution to the coupled Einstein-Higgs equations
for general Higgs-type potentials in the context of flat FRW cosmological
models. Possible implications are discussed.Comment: 5 pages, no figures. Version to be published in Phys. Rev. Lett.
Changes: references and citations added; introduction partly modified;
expanded discussion of relations between parameters in the Higgs potentia
A Toy Model for Open Inflation
The open inflation scenario based on the theory of bubble formation in the
models of a single scalar field suffered from a fatal defect. In all the
versions of this scenario known so far, the Coleman-De Luccia instantons
describing the creation of an open universe did not exist. We propose a simple
one-field model where the CDL instanton does exist and the open inflation
scenario can be realized.Comment: 7 pages, 4 figures, revtex, a discussion of density perturbations is
extende
Cosmic scalar fields with flat potential
The dynamics of cosmic scalar fields with flat potential is studied. Their
contribution to the expansion rate of the universe is analyzed, and their
behaviour in a simple model of phase transitions is discussed.Comment: 9 page
The Triple-Alpha Process and the Anthropically Allowed Values of the Weak Scale
In multiple-universe models, the constants of nature may have different
values in different universes. Agrawal, Barr, Donoghue and Seckel have pointed
out that the Higgs mass parameter, as the only dimensionful parameter of the
standard model, is of particular interest. By considering a range of values of
this parameter, they showed that the Higgs vacuum expectation value must have a
magnitude less than 5.0 times its observed value, in order for complex
elements, and thus life, to form. In this report, we look at the effects of the
Higgs mass parameter on the triple-alpha process in stars. This process, which
is greatly enhanced by a resonance in Carbon-12, is responsible for virtually
all of the carbon production in the universe. We find that the Higgs vacuum
expectation value must have a magnitude greater than 0.90 times its observed
value in order for an appreciable amount of carbon to form, thus significantly
narrowing the allowed region of Agrawal et al.Comment: 9 pages, 1 figur
Inflation without Slow Roll
We draw attention to the possibility that inflation (i.e. accelerated
expansion) might continue after the end of slow roll, during a period of fast
oscillations of the inflaton field \phi . This phenomenon takes place when a
mild non-convexity inequality is satisfied by the potential V(\phi). The
presence of such a period of \phi-oscillation-driven inflation can
substantially modify reheating scenarios.
In some models the effect of these fast oscillations might be imprinted on
the primordial perturbation spectrum at cosmological scales.Comment: 9 pages, Revtex, psfig, 1 figure, minor modifications, references
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The Consistent Result of Cosmological Constant From Quantum Cosmology and Inflation with Born-Infeld Scalar Field
The Quantum cosmology with Born-Infeld(B-I) type scalar field is considered.
In the extreme limits of small cosmological scale factor the wave function of
the universe can also be obtained by applying the methods developed by
Hartle-Hawking(H-H) and Vilenkin. H-H wave function predicts that most Probable
cosmological constant equals to (
equals to the maximum of the kinetic energy of scalar field). It is different
from the original results() in cosmological constant obtained by
Hartle-Hawking. The Vilenkin wave function predicts a nucleating unverse with
largest possible cosmological constant and it is larger than . The
conclusions have been nicely to reconcile with cosmic inflation. We investigate
the inflation model with B-I type scalar field, and find that depends on
the amplitude of tensor perturbation , with the form
The vacuum energy in inflation epoch depends on the
tensor-to-scalar ratio . The amplitude of the
tensor perturbation can, in principle, be large enough to be
discovered. However, it is only on the border of detectability in future
experiments. If it has been observed in future, this is very interesting to
determine the vacuum energy in inflation epoch.Comment: 12 pages, one figure, references added, accepted by European Physical
Journal
Inflation and Large Internal Dimensions
We consider some aspects of inflation in models with large internal
dimensions. If inflation occurs on a 3D wall after the stabilization of
internal dimensions in the models with low unification scale (M ~ 1 TeV), the
inflaton field must be extremely light. This problem may disappear In models
with intermediate (M ~10^{11} GeV) to high (M ~ 10^{16} GeV) unification scale.
However, in all of these cases the wall inflation does not provide a complete
solution to the horizon and flatness problems. To solve them, there must be a
stage of inflation in the bulk before the compactification of internal
dimensions.Comment: 4 pages, revtex, minor modification
Some Connections between Quantum Tunneling and Inflation
The Wheeler-DeWitt equation in the minisuperspace approximation is studied in
four different models. Under certain circumstances each model leads to a
tunneling potential and under the same circumstances the classical version of
each model leads to inflation.Comment: 11 pages, 1 figure, accepted for publication in Physics Letters
Sub-eV scalar dark matter through the super-renormalizable Higgs portal
The Higgs portal of the Standard Model provides the opportunity for coupling
to a very light scalar field via the super-renormalizable operator
. This allows for the existence of a very light scalar dark
matter that has coherent interaction with the Standard Model particles and yet
has its mass protected against radiative corrections. We analyze ensuing
constraints from the fifth-force measurements, along with the cosmological
requirements. We find that the detectable level of the fifth-force can be
achieved in models with low inflationary scales, and certain amount of
fine-tuning in the initial deviation of from its minimum.Comment: 6 pages, 3 figures. References added in the revised version
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