2,156 research outputs found

    Radiation Information from 1958 δ2

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    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

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    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 a(t)a(t). 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

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    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

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    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 pp-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

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    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

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    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

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    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

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    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

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    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

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    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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