In this paper we point out that Starobinky inflation could be induced by quantum effects due to a large non-minimal coupling of the Higgs boson Ricci scalar. The Starobinsky mechanism provides solution issues attached field values in early universe which metastable would not viable option. We verify explicitly these corrections do destabilize Starobinsky's potential.

Abstract It is well-known that the results by Bekenstein, Gibbons and Hawking on thermodynamics of black holes can be reproduced quite simply in Euclidean path integral approach to Quantum Gravity. The corresponding partition function obtained semiclassically, ultimately requiring only on-shell Einstein--Hilbert action with opportune asymptotic subtractions. We elaborate fact same expressions for thermodynamical quantities within teleparallel equivalent theories, based either torsion or...

We investigate how competitive gravitational wave detectors can be to current and near-future colliders in probing a model where the new physics is completely encapsulated modified scalar sector. For this, we study an additional logarithmic term arises potential due non-trivial path integral measure, which constructed using effective field theory. This alters dynamics of cosmological phase transitions could lead potentially detectable waves from early Universe. Our results confirm...

An obvious criterion to classify theories of modified gravity is identify their gravitational degrees freedom and coupling the metric matter sector. Using this simple idea, we show that any theory which depends on curvature invariants equivalent general relativity in presence new fields are gravitationally coupled energy-momentum tensor. We they can be shifted into a There no priori reason these as or fields. This leads an equivalence between dark particles standard model designed account...

The notions of minimum geometrical length and scale are discussed with reference to correlation functions obtained from in-in in-out amplitudes in quantum field theory. Whereas the propagator for metric perturbations does not admit former, Feynman shows emergence latter. A connection between theories gravity deformation parameter δ0 generalised uncertainty principle (GUP) is then exhibited, which allows determine an exact expression terms residues causal propagator. correspondence...

The presence of a functional measure is scrutinized on both sides the dual gauge/gravity correspondence. Corrections to transport coefficients in relativistic hydrodynamics are obtained using linear response procedure. In particular, first-order hydrodynamics, shear viscosity, entropy density, diffusion constant, and speed sound shown not acquire any corrections from gravity, for Minkowski background metric. On other hand, energy pressure, relaxation time, bulk decay rate waves, conformal...

Abstract The Hawking radiation of static, spherically symmetric, asymptotically flat solutions in quadratic gravity is here scrutinized, the context generalized uncertainty principle (GUP). Near-center and near-horizon Frobenius expansions these are studied. Their thermal spectrum investigated out tunnelling method WKB procedure. Computing flux black hole shows that, for small holes a precise combination GUP parameter parameters that govern gravitational interaction gravity, luminosity can...

The purpose of this work is to investigate the consequences quantum gravity for singularity problem. We study higher-derivative terms that invariably appear in any field theoretical model gravity, handling them both non-perturbatively and perturbatively. In former case, by computing contributions additional degrees freedom a congruence geodesics, we show appearance singularities no longer necessity. latter, which corresponds treating quantised general relativity as an effective theory,...

In this short paper we investigate quantum gravitational effects on Einstein's equations using Effective Field Theory techniques. We consider the leading order correction to wave equation. Besides usual massless mode, find a pair of modes with complex masses. These massive particles have width and could thus lead damping waves if excited in violent astrophysical processes producing such as e.g. black hole mergers. discuss consequences for events GW 150914 recently observed by Advanced LIGO...

The assumptions of the Hawking–Penrose singularity theorem are not covariant under field redefinitions. Following works on formulation quantum theory initiated by Vilkovisky and DeWitt in 80s, we propose to study singularities space, where spacetime metric is treated as a coordinate along with other fields theory. From this viewpoint, might be just field-space coordinates, analogously standard General Relativity. Objects invariant transformations can then reveal whether certain indeed...

Abstract We compute quantum corrections for the gravitational potential obtained by including a derivative self-coupling in its classical dynamics as toy model analysing gravity strong field regime. In particular, we focus on to solutions vacuum outside localised matter sources.

We determine the complete space-time metric from bootstrapped Newtonian potential generated by a static spherically symmetric source in surrounding vacuum. This contains post-Newtonian parameters which can be further used to constrain underlying dynamical theory and quantum state of gravity. For values within experimental bounds, reconstructed appears very close Schwarzschild solution general relativity whole region outside event horizon. The latter is however larger size for same value mass...

It is rather well-known that spacetime singularities are not covariant under field redefinitions. A manifestly approach to in classical gravity was proposed [1]. In this paper, we start extend analysis the quantum realm. We identify two types of space corresponding geodesic incompleteness and ill-defined path integrals (hereby dubbed functional singularities). argue former might be harmful after all, whilst latter makes all observables undefined. show path-integral measure regular any...

In the absence of new physics around 1010 GeV, electroweak vacuum is at best metastable. This represents a major challenge for high scale inflationary models as, during early rapid expansion universe, it seems difficult to understand how Higgs would not decay true lower theory with catastrophic consequences if inflation took place above GeV. this paper we show that non-minimal coupling boson curvature could solve problem by generating direct potential thereby stabilizing vacuum. For specific...

Abstract We consider the quantization of matter fields in a background described by teleparallel equivalent to general relativity. The presence local Lorentz and gauge symmetries gives rise different coupling prescriptions, which we analyse separately. As expected, quantum produce divergences that cannot be absorbed terms action Nonetheless, formulation gravity allows one find out source problem. By imposing invariance after quantization, show modified gravity, coefficients are replaced free...

We show that quantum gravity yields exponentially growing gravitational waves. Without a mechanism to stop these modes from growing, the universe would go through collapse. For Minkowski background, we propose solution by choosing an integration contour in Fourier space does not enclose problematic modes, thus preventing them showing up effective theory. It turns out this is only possible when are removed altogether. expanding universe, argue runaway can be managed accordingly dynamics of...

It has been shown that the spectrum of quantum gravity contains at least two new modes in addition to massless graviton: a massive spin-0 and spin-2. We calculate their power during inflation we argue they could leave an imprint cosmic microwave background should masses be below inflationary scale.

Effective field theory techniques are used to study the leading order quantum corrections gravitational wave backreaction. The effective stress-energy tensor is calculated and it shown that has a non-vanishing trace contributes cosmological constant. By comparing result obtained with LIGO's data, first bound on amplitude of massive mode found: $$\epsilon < 1.4\times 10^{-33}$$ .

We study quantum corrections at one-loop order to the shear viscosity entropy ratio by implementing Vilkovisky-Barvinsky effective action in asymptotically Anti-de Sitter spacetimes. The is shown receive no this order, but acquires a logarithmic correction. coefficient of logarithm turns out depend on spin particles running loop and it can be either positive or negative. On basis result, we argue that Kovtun-Son-Starinets bound cannot seen as fundamental property nature beyond classical regime.

Abstract We remark that Ostrogradsky ghosts in higher-derivative gravity, with a finite number of derivatives, are fictitious as they result from an unjustified truncation performed complete theory containing infinitely many curvature invariants. The apparent can then be projected out the quadratic gravity spectrum by redefining boundary conditions terms integration contour does not enclose ghost poles. This procedure alter renormalizability theory. One thus use quantum field is both...

Abstract The existence of a minimum length in quantum gravity is investigated by computing the in-in expectation value proper distance Schwinger–Keldysh formalism. No geometrical found for arbitrary gravitational theories to all orders perturbation theory. Using non-perturbative techniques, we also show that neither conformal sector general relativity nor higher-derivative features length. A scale, on other hand, seems always be present when one considers in-out amplitudes, from which could...

The effective action for quantum gravity coupled to matter contains corrections arising from the functional measure. We analyse effect of such anisotropic self-gravitating compact objects described by means gravitational decoupling method applied isotropic solutions Einstein field equations. In particular, we consider Tolman IV solution general relativity and show that effects can modify energy density as well tangential radial pressures. For a suitable choice mimicking constant, upper...