1,873 research outputs found

    Primordial Power Spectra from Anisotropic Inflation

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    We examine cosmological perturbations in a dynamical theory of inflation in which an Abelian gauge field couples directly to the inflaton, breaking conformal invariance. When the coupling between the gauge field and the inflaton takes a specific form, inflation becomes anisotropic and anisotropy can persist throughout inflation, avoiding Wald's no-hair theorem. After discussing scenarios in which anisotropy can persist during inflation, we calculate the dominant effects of a small persistent anisotropy on the primordial gravitational wave and curvature perturbation power spectra using the "in-in" formalism of perturbation theory. We find that the primordial power spectra of cosmological perturbations gain significant direction dependence and that the fractional direction dependence of the tensor power spectrum is suppressed in comparison to that of the scalar power spectrum.Comment: 25 pages, 2 figures; References added, typos corrected and some discussion expanded; version submitted for publication in PR

    Local Law Enforcement\u27s Ability to Transform Inputs Into Counterterrorism Outputs

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    Leadership within local police organizations should be able to, but do not, process information and create actionable strategies aimed toward proactive counterterrorism practices. This problem could lead to future terrorist attacks within the United States if police agencies do not adjust their tactics in response to growing terrorist threats. A possible cause of this problem is that leadership within local law enforcement agencies is reactive in nature and as a consequence, do not encourage officers to engage in proactive strategies. Using Easton\u27s conceptualization of systems theory as the foundation, the purpose of this case study of a single law enforcement agency in the southwest was to explore how police leadership influences counterterrorism strategies. Research questions focused on how police leadership processed information within their organization to develop counterterrorism tactics. Data were collected from interviews with police leadership and officers, observations of policing activities, and document review of policies, directives, and unclassified reports. These data were coded and analyzed following Yin\u27s procedure for schematic analysis. The results indicated that this agency has a successful counterterrorism strategy based on 6 organizational pillars of leading, proactive, learning, processing, policy, and communication. This study may promote positive social change by helping police leaders identify which system inputs provide the best detail for developing counterterrorism policy, and what community partnerships help police identify terrorism threats

    A solid-reagent dispenser for use in the azocoll protease assay (and other insoluble substrate analyses).

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    A solid-reagent dispenser for use in the azocoll protease assay (and other insoluble substrate analyses)

    Top A_FB at the Tevatron vs. charge asymmetry at the LHC in chiral U(1) flavor models with flavored Higgs doublets

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    We consider the top forward-backward (FB) asymmetry at the Tevatron and top charge asymmetry at the LHC within chiral U(1)^\prime models with flavor-dependent U(1)^\prime charges and flavored Higgs fields, which were introduced in the ref. [65]. The models could enhance not only the top forward-backward asymmetry at Tevatron, but also the top charge asymmetry at LHC, without too large same-sign top pair production rates. We identify parameter spaces for the U(1)^\prime gauge boson and (pseudo)scalar Higgs bosons where all the experimental data could be accommodated, including the case with about 125 GeV Higgs boson, as suggested recently by ATLAS and CMS.Comment: 11 pages, 6 figures, figures and discussion adde

    Noether Symmetry Approach in "Cosmic Triad" Vector Field Scenario

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    To realize the accelerations in the early and late periods of our universe, we need to specify potentials for the dominant fields. In this paper, by using the Noether symmetry approach, we try to find suitable potentials in the "cosmic triad" vector field scenario. Because the equation of state parameter of dark energy has been constrained in the range of −1.21≤ω≤−0.89-1.21\leq \omega\leq -0.89 by observations, we derive the Noether conditions for the vector field in quintessence, phantom and quintom models, respectively. In the first two cases, constant potential solutions have been obtained. What is more, a fast decaying point-like solution with power-law potential is also found for the vector field in quintessence model. For the quintom case, we find an interesting constraint C~Vp′=−CVq′\tilde{C}V_{p}'=-CV_{q}' on the field potentials, where CC and C~\tilde{C} are constants related to the Noether symmetry.Comment: 15 pages, no figures, accepted by Classical and Quantum Gravity

    Top quark forward-backward asymmetry in R-parity violating supersymmetry

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    The interaction of bottom squark-mediated top quark pair production, occurring in the R-parity violating minimal supersymmetric standard model (MSSM), is proposed as an explanation of the anomalously large ttˉt\bar{t} forward-backward asymmetry (FBA) observed at the Tevatron. We find that this model can give a good fit to top quark data, both the inclusive and invariant mass-dependent asymmetries, while remaining consistent (at the 2-σ\sigma level) with the total and differential production cross-sections. The scenario is challenged by strong constraints from atomic parity violation (APV), but we point out an extra diagram for the effective down quark-Z vertex, involving the same coupling constant as required for the FBA, which tends to weaken the APV constraint, and which can nullify it for reasonable values of the top squark masses and mixing angle. Large contributions to flavor-changing neutral currents can be avoided if only the third generation of sparticles is light.Comment: 24 pages, 7 figures. v3: included LHC top production cross section data; model still consistent at 2 sigma leve
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