2,156 research outputs found
Radiation Information from 1958 δ2
The telemetered radiation information from the satellite 1958 δ2
(Sputnik III) has been analyzed for sixty-two separate passes recorded
in College, Alaska. The data indicate a dependence of radiation intensity
on altitude in the range 250-500 km. Both the high and low
energy components apparently contribute to the overall increase of
intensity with altitude, but the presence of a continuous afterglow
in the scintillating crystal prevented detailed interpretation of the
results.IGY Project No. 32.42
NSF Grant No. Y/32.42/268Ye
Ultraviolet Divergences in Cosmological Correlations
A method is developed for dealing with ultraviolet divergences in
calculations of cosmological correlations, which does not depend on dimensional
regularization. An extended version of the WKB approximation is used to analyze
the divergences in these calculations, and these divergences are controlled by
the introduction of Pauli--Villars regulator fields. This approach is
illustrated in the theory of a scalar field with arbitrary self-interactions in
a fixed flat-space Robertson--Walker metric with arbitrary scale factor .
Explicit formulas are given for the counterterms needed to cancel all
dependence on the regulator properties, and an explicit prescription is given
for calculating finite regulator-independent correlation functions. The
possibility of infrared divergences in this theory is briefly considered.Comment: References added on various regularization methods. Improved
discussion of further issues. 26 pages, 1 figur
Wheeler-DeWitt Quantization of Gravity Models of Unified Dark Energy and Dark Matter
First, we describe the construction of a new type of gravity-matter models
based on the formalism of non-Riemannian space-time volume forms - alternative
generally covariant integration measure densities (volume elements) defined in
terms of auxiliary antisymmetric tensor gauge fields. Here gravity couples in a
non-conventional way to two distinct scalar fields providing a unified
Lagrangian action principle description of: (i) the evolution of both "early"
and "late" Universe - by the "inflaton" scalar field; (ii) dark energy and dark
matter as a unified manifestation of a single material entity - the "darkon"
scalar field. A physically very interesting phenomenon occurs when including in
addition interactions with the electro-weak model bosonic sector - we obtain a
gravity-assisted dynamical generation of electro-weak spontaneous gauge
symmetry breaking in the post-inflationary "late" Universe, while the
Higgs-like scalar remains massless in the "early" Universe. Next, we proceed to
the Wheeler-DeWitt minisuperspace quantization of the above models. The
"darkon" field plays here the role of cosmological "time". In particular, we
show the absence of cosmological space-time singularities.Comment: 15 pages, to be published in the Proceedings of QTS10 - 10th
International Symposium "Quantum Theory and Symmetries" (Varna, 2017),
Springer Proceedings in Mathematics and Statistics, V. Dobrev (ed.). arXiv
admin note: text overlap with arXiv:1609.0691
Quantum Equivalence of Massive Antisymmetric Tensor Field Models in Curved Space
We study the effective actions for massive rank-2 and rank-3 antisymmetric
tensor field models in curved space-time. These models are classically
equivalent to massive vector field and massive scalar field with minimal
coupling to gravity respectively. We prove that effective action for massive
rank-2 antisymmetric tensor field is exactly equal to one for massive vector
field and effective action for massive rank-3 antisymmetric tensor field is
exactly equal to one for massive scalar field. Prove is based on an identity
for mass-dependent zeta-functions associated with Laplacians acting on
-forms.Comment: 8 pages, REVTeX fil
The Impact of Prolonged Nomination Contests on Presidential Candidate Evaluations and General Election Vote Choice: The Case of 2008
The fact that political parties hold competitive nomination contests that require voters to choose among multiple candidates leaves open the possibility that the contest itself could damage the prospects of an eventual nominee. In this study, we employ the American National Election Study panel survey data from the 2008 U.S. presidential election to assess the impact of the Democratic Party nomination process on candidate evaluations and general election vote preference. We find evidence that Barack Obama had greater difficulty uniting his party than his Republican counterpart due to the fact that Clinton voters were slow to coalesce around Obama. These supporters failed to report higher levels of favorability until Clinton conceded the race in the summer, while Huckabee and Romney voters were seen rallying to their party\u27s nominee in the spring. In the end, many Clinton primary voters either abstained from voting in November or crossed over to support the Republican nominee
Quantum gravity at a TeV and the renormalization of Newton's constant
We examine whether renormalization effects can cause Newton¿s constant to change dramatically with energy, perhaps even reducing the scale of quantum gravity to the TeV region without the introduction of extra dimensions. We examine a model that realizes this possibility and describe experimental signatures from the production of small black holes
The Fermion Self-Energy during Inflation
We compute the one loop fermion self-energy for massless Dirac + Einstein in
the presence of a locally de Sitter background. We employ dimensional
regularization and obtain a fully renormalized result by absorbing all
divergences with BPHZ counterterms. An interesting technical aspect of this
computation is the need for a noninvariant counterterm owing to the breaking of
de Sitter invariance by our gauge condition. Our result can be used in the
quantum-corrected Dirac equation to search for inflation-enhanced quantum
effects from gravitons, analogous to those which have been found for massless,
minimally coupled scalars.Comment: 63 pages, 3 figures (uses axodraw.sty), LaTeX 2epsilon. Revised
version (to appear in Classical and Quantum Gravity) corrects some typoes and
contains some new reference
van Vleck determinants: geodesic focussing and defocussing in Lorentzian spacetimes
The van Vleck determinant is an ubiquitous object, arising in many physically
interesting situations such as: (1) WKB approximations to quantum time
evolution operators and Green functions. (2) Adiabatic approximations to heat
kernels. (3) One loop approximations to functional integrals. (4) The theory of
caustics in geometrical optics and ultrasonics. (5) The focussing and
defocussing of geodesic flows in Riemannian manifolds. While all of these
topics are interrelated, the present paper is particularly concerned with the
last case and presents extensive theoretical developments that aid in the
computation of the van Vleck determinant associated with geodesic flows in
Lorentzian spacetimes. {\sl A fortiori} these developments have important
implications for the entire array of topics indicated. PACS: 04.20.-q,
04.20.Cv, 04.60.+n. To appear in Physical Review D47 (1993) 15 March.Comment: plain LaTeX, 18 page
Updating Prior Beliefs based on Ambiguous Evidence
This paper investigates a problem where the solver must
firstly determine which of two possible causes are the source
of an effect where one cause has a historically higher
propensity to cause that effect. Secondly, they must update the
propensity of the two causes to produce the effect in light of
the observation. Firstly, we find an error commensurate with
the ‘double updating’ error observed within the polarisation
literature: individuals appear to first use their prior beliefs to
interpret the evidence, then use the interpreted form of the
evidence, rather than the raw form, when updating. Secondly,
we find an error where individuals convert from a
probabilistic representation of the evidence to a categorical
one and use this representation when updating. Both errors
have the effect of exaggerating the evidence in favour of the
solver’s prior belief and could lead to confirmation bias and
polarisation
Using genotype abundance to improve phylogenetic inference
Modern biological techniques enable very dense genetic sampling of unfolding
evolutionary histories, and thus frequently sample some genotypes multiple
times. This motivates strategies to incorporate genotype abundance information
in phylogenetic inference. In this paper, we synthesize a stochastic process
model with standard sequence-based phylogenetic optimality, and show that tree
estimation is substantially improved by doing so. Our method is validated with
extensive simulations and an experimental single-cell lineage tracing study of
germinal center B cell receptor affinity maturation
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