1,721,036 research outputs found
Quantum Gravitational Corrections in Cosmology
Full text linkWe show how to reliably calculate quantum gravitational corrections to cosmological models using the unique effective action formalism for quantum gravity. Our calculations are model independent and apply to any ultraviolet complete theory of quantum gravity that admit general relativity as a low energy theory. We show that it is
important to consider the full effective action to obtain renormalization group invariant solutions. We investigate the validity range of our techniques within simple cosmological models
What is the final state of a black hole merger?
No full textIn this short paper, we discuss the possibility of testing the nature of astrophysical black holes using the recently observed black hole mergers. We investigate the possibility that a secondary black hole is created in the merger of two astrophysical black holes and discuss potential astrophysical signatures. We point out that black hole mergers are a possible astrophysical mechanism for the creation of quantum black holes with masses close to the Planck mass
Quantum black holes and their lepton signatures at the LHC with CalCHEP
No full textWe discuss a field theoretical framework to describe the interactions of non-thermal quantum black holes (QBHs) with particles of the Standard Model. We propose a non-local Lagrangian to describe the production of these QBHs which is designed to reproduce the geometrical cross section prs2 for black hole production where rs is the Schwarzschild radius. This model is implemented into CalcHEP package and is publicly available at the High Energy Model Database (HEPMDB) for simulation of QBH events at the LHC and future colliders. We present the first phenomenological application of the QBH@HEPMDB model with spin-0 neutral QBH giving rise the e+e- and eµ signatures at the LHC@8TeV and LHC@13TeV and produce the respective projections for the LHC in terms of limits on the reduced Planck mass, M¯PL and the number of the extra-dimensions n
Quantum corrected equations of motion in the interior and exterior Schwarzschild spacetimes
Full text linkIn this paper we derive the leading quantum gravitational corrections to the geodesics and the equations of motion for a scalar field in the spacetime containing a constant density star. It is shown that these corrections can be calculated in quantum gravity reliably and in a model independent way. Furthermore, we find that quantum gravity gives rise to an additional redshift that results from the gradient instead of the amplitude of the density profile
Quantum gravitational corrections to a star metric and the black hole limit
No full textIn this paper we consider the full set of quantum gravitational corrections to a star metric to second order in curvature. As we use an effective field theoretical approach, these corrections apply to any model of quantum gravity that is based on general coordinate invariance. We then discuss the black hole limit and identify an interesting phenomenon which could shed some light on the nature of astrophysical black holes: while star metrics receive corrections at second order in curvature, vacuum solutions such as black hole metrics do not. What happens to these corrections when a star collapses
Quantum Hair During Gravitational Collapse
Full text linkWe consider quantum gravitational corrections to the Oppenheimer-Snyder
metric describing time-dependent dust ball collapse. The interior metric also
describes Friedmann-Lemaitre-Robertson-Walker cosmology and our results are
interpreted in that context. The exterior corrections are an example of quantum
hair, and are shown to persist throughout the collapse. Our results show the
quantum hair survives throughout the horizon formation and that the internal
state of the resulting black hole is accessible to outside observers.Comment: 13 page
Gravitational effective action at second order in curvature and gravitational waves
Full text linkAbstract We consider the full effective theory for quantum gravity at second order in curvature including non-local terms. We show that the theory contains two new degrees of freedom beyond the massless graviton: namely a massive spin-2 ghost and a massive scalar field. Furthermore, we show that it is impossible to fine-tune the parameters of the effective action to eliminate completely the classical spin-2 ghost because of the non-local terms in the effective action. Being a classical field, it is not clear anyway that this ghost is problematic. It simply implies a repulsive contribution to Newton’s potential. We then consider how to extract the parameters of the effective action and show that it is possible to measure, at least in principle, the parameters of the local terms independently of each other using a combination of observations of gravitational waves and measurements performed by pendulum type experiments searching for deviations of Newton’s potential
Singularities in quantum corrected space-times
Full text linkIn this paper we consider a static and regular fluid generating a locally spherically symmetric and time-independent space-time and calculate the leading quantum corrections to the metric to first order in curvature. Starting from a singularity free classical solution of general relativity, we show that singularities can be introduced in the curvature invariants by quantum gravitational corrections calculated using an effective field theory approach to quantum gravity. We identify non-trivial conditions that ensure that curvature invariants remain singularity free to leading order in the curvature expansion of the effective action
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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