108 research outputs found

    Attributions for Rejection and Acceptance in Young Adults with Borderline and Avoidant Personality Features

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    Individuals with borderline and avoidant personality disorders show interpersonal dysfunction that includes maladaptive responses to rejection and reduced emotional benefits from acceptance. To identify the attributional styles that may underlie these difficulties, we examined causal attributions for rejection and acceptance among undergraduates high in features of each disorder and a healthy comparison group. In Study 1, participants rated how likely they were to attribute hypothetical rejection and acceptance experiences to positive and negative qualities of the self and others, as well as external circumstances. In Study 2, we examined these same attributions in daily diary assessments of real rejection and acceptance experiences. Although the two studies showed some differences in results, they both linked borderline personality features with suspicious, selfbolstering responses and avoidant personality features with perceived inferiority. Distinct attributional styles may contribute to the distinct interpersonal problems characteristic of these conditions

    Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale

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    We conducted three torsion-balance experiments to test the gravitational inverse-square law at separations between 9.53 mm and 55 micrometers, probing distances less than the dark-energy length scale λd=ℏc/ρd4≈85ÎŒ\lambda_{\rm d}=\sqrt[4]{\hbar c/\rho_{\rm d}}\approx 85 \mum. We find with 95% confidence that the inverse-square law holds (âˆŁÎ±âˆŁâ‰€1|\alpha| \leq 1) down to a length scale λ=56ÎŒ\lambda = 56 \mum and that an extra dimension must have a size R≀44ÎŒR \leq 44 \mum.Comment: 4 pages, 6 figure

    f(R) actions, cosmic acceleration and local tests of gravity

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    We study spherically symmetric solutions in f(R) theories and its compatibility with local tests of gravity. We start by clarifying the range of validity of the weak field expansion and show that for many models proposed to address the Dark Energy problem this expansion breaks down in realistic situations. This invalidates the conclusions of several papers that make inappropriate use of this expansion. For the stable models that modify gravity only at small curvatures we find that when the asymptotic background curvature is large we approximately recover the solutions of Einstein gravity through the so-called Chameleon mechanism, as a result of the non-linear dynamics of the extra scalar degree of freedom contained in the metric. In these models one would observe a transition from Einstein to scalar-tensor gravity as the Universe expands and the background curvature diminishes. Assuming an adiabatic evolution we estimate the redshift at which this transition would take place for a source with given mass and radius. We also show that models of dynamical Dark Energy claimed to be compatible with tests of gravity because the mass of the scalar is large in vacuum (e.g. those that also include R^2 corrections in the action), are not viable.Comment: 26 page

    Renormalization group improved black hole space-time in large extra dimensions

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    By taking into account a running of the gravitational coupling constant with an ultra violet fixed point, an improvement of classical black hole space-times in extra dimensions is studied. It is found that the thermodynamic properties in this framework allow for an effective description of the black hole evaporation process. Phenomenological consequences of this approach are discussed and the LHC discovery potential is estimated.Comment: 13 pages, 6 figure

    Probing the dark matter issue in f(R)-gravity via gravitational lensing

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    For a general class of analytic f(R)-gravity theories, we discuss the weak field limit in view of gravitational lensing. Though an additional Yukawa term in the gravitational potential modifies dynamics with respect to the standard Newtonian limit of General Relativity, the motion of massless particles results unaffected thanks to suitable cancellations in the post-Newtonian limit. Thus, all the lensing observables are equal to the ones known from General Relativity. Since f(R)-gravity is claimed, among other things, to be a possible solution to overcome for the need of dark matter in virialized systems, we discuss the impact of our results on the dynamical and gravitational lensing analyses. In this framework, dynamics could, in principle, be able to reproduce the astrophysical observations without recurring to dark matter, but in the case of gravitational lensing we find that dark matter is an unavoidable ingredient. Another important implication is that gravitational lensing, in the post-Newtonian limit, is not able to constrain these extended theories, since their predictions do not differ from General Relativity.Comment: 7 pages, accepted for publication in EPJ

    Noncommutative geometry inspired black holes in higher dimensions at the LHC

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    When embedding models of noncommutative geometry inspired black holes into the peridium of large extra dimensions, it is natural to relate the noncommutativity scale to the higher-dimensional Planck scale. If the Planck scale is of the order of a TeV, noncommutative geometry inspired black holes could become accessible to experiments. In this paper, we present a detailed phenomenological study of the production and decay of these black holes at the Large Hadron Collider (LHC). Noncommutative inspired black holes are relatively cold and can be well described by the microcanonical ensemble during their entire decay. One of the main consequences of the model is the existence of a black hole remnant. The mass of the black hole remnant increases with decreasing mass scale associated with noncommutative and decreasing number of dimensions. The experimental signatures could be quite different from previous studies of black holes and remnants at the LHC since the mass of the remnant could be well above the Planck scale. Although the black hole remnant can be very heavy, and perhaps even charged, it could result in very little activity in the central detectors of the LHC experiments, when compared to the usual anticipated black hole signatures. If this type of noncommutative inspired black hole can be produced and detected, it would result in an additional mass threshold above the Planck scale at which new physics occurs.Comment: 21 pages, 7 figure

    Dark Energy and Extending the Geodesic Equations of Motion: Its Construction and Experimental Constraints

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    With the discovery of Dark Energy, ΛDE\Lambda_{DE}, there is now a universal length scale, ℓDE=c/(ΛDEG)1/2\ell_{DE}=c/(\Lambda_{DE} G)^{1/2}, associated with the universe that allows for an extension of the geodesic equations of motion. In this paper, we will study a specific class of such extensions, and show that contrary to expectations, they are not automatically ruled out by either theoretical considerations or experimental constraints. In particular, we show that while these extensions affect the motion of massive particles, the motion of massless particles are not changed; such phenomena as gravitational lensing remain unchanged. We also show that these extensions do not violate the equivalence principal, and that because ℓDE=14010820800\ell_{DE}=14010^{800}_{820} Mpc, a specific choice of this extension can be made so that effects of this extension are not be measurable either from terrestrial experiments, or through observations of the motion of solar system bodies. A lower bound for the only parameter used in this extension is set.Comment: 19 pages. This is the published version of the first half of arXiv:0711.3124v2 with corrections include

    Strong laser fields as a probe for fundamental physics

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    Upcoming high-intensity laser systems will be able to probe the quantum-induced nonlinear regime of electrodynamics. So far unobserved QED phenomena such as the discovery of a nonlinear response of the quantum vacuum to macroscopic electromagnetic fields can become accessible. In addition, such laser systems provide for a flexible tool for investigating fundamental physics. Primary goals consist in verifying so far unobserved QED phenomena. Moreover, strong-field experiments can search for new light but weakly interacting degrees of freedom and are thus complementary to accelerator-driven experiments. I review recent developments in this field, focusing on photon experiments in strong electromagnetic fields. The interaction of particle-physics candidates with photons and external fields can be parameterized by low-energy effective actions and typically predict characteristic optical signatures. I perform first estimates of the accessible new-physics parameter space of high-intensity laser facilities such as POLARIS and ELI.Comment: 7 pages, Key Lecture at the ELI Workshop and School on "Fundamental Physics with Ultra-High Fields", 9 September - 2 October 2008 at Frauenworth Monastery, German
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