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Loop Quantum Gravity is a background independent, nonperturbative approach to the quantization of General Relativity. Its application to models of interest in cosmology and astrophysics, known as Loop Quantum Cosmology, has led to new and…

General Relativity and Quantum Cosmology · Physics 2015-05-27 Guillermo A. Mena Marugan

A short introduction is given on the functional renormalization group method, putting emphasis on its nonperturbative aspects. The method enables to find nontrivial fixed points in quantum field theoretic models which make them free from…

High Energy Physics - Theory · Physics 2014-08-15 Sandor Nagy

The gravity is classically formulated as the geometric curvature of the space-time in general relativity which is completely different from the other well-known physical forces. Since seeking a quantum framework for the gravity is a great…

High Energy Physics - Theory · Physics 2014-09-29 Cao H. Nam

We investigate the consequences of combining swampland conjectures with the requirement of asymptotic safety. To this end, we explore the infrared regime of asymptotically safe gravity in the quadratic one-loop approximation, and we…

High Energy Physics - Theory · Physics 2021-10-20 Ivano Basile , Alessia Platania

It is proposed that if quantum states of space-time are coherent on null surfaces, holographic Planck-scale fluctuations of inflationary horizons dominate the formation of primordial scalar curvature perturbations. It is shown that the…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-17 Craig Hogan

In this contribution, we discuss the asymptotic safety scenario for quantum gravity with a functional renormalisation group approach that disentangles dynamical metric fluctuations from the background metric. We review the state of the art…

High Energy Physics - Theory · Physics 2021-12-03 Jan M. Pawlowski , Manuel Reichert

A self-consistent pre-inflationary extension of the inflationary scenario with the Starobinsky potential, favored by Planck data, is studied using techniques from loop quantum cosmology (LQC). The results are compared with the quadratic…

General Relativity and Quantum Cosmology · Physics 2016-05-25 Béatrice Bonga , Brajesh Gupt

We explore the possibility that the fundamental theory of nature does not contain any scale. This implies a renormalizable quantum gravity theory where the graviton kinetic term has 4 derivatives, and can be reinterpreted as gravity minus…

High Energy Physics - Phenomenology · Physics 2017-05-11 Alberto Salvio , Alessandro Strumia

It is sometimes argued that observation of tensor modes from inflation would provide the first evidence for quantum gravity. However, in the usual inflationary formalism, also the scalar modes involve quantised metric perturbations. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-05 Tommi Markkanen , Syksy Rasanen , Pyry Wahlman

Asymptotically safe gravity is based on the idea of the dependence of the gravitational coupling upon the distance from the origin, approaching its classical value in the weak field regime. We consider three cases of identifying the cut-off…

General Relativity and Quantum Cosmology · Physics 2024-04-04 A. F. Zinhailo

We discuss the cosmological inflation in the context of $f(Q)$ non-metric gravity, where $Q$ is the non-metric scalar. After introducing conformal transformations for $f(Q)$ gravity, we first focus on the potential-slow-roll inflation by…

General Relativity and Quantum Cosmology · Physics 2022-09-23 Salvatore Capozziello , Mehdi Shokri

We display some simple cosmological solutions of gravity theories with quadratic Ricci curvature terms added to the Einstein-Hilbert lagrangian which exhibit anisotropic inflation. The Hubble expansion rates are constant and unequal in…

General Relativity and Quantum Cosmology · Physics 2010-04-21 J. D. Barrow , S. Hervik

A phenomenologically viable theory of quantum gravity must accommodate all observed matter degrees of freedom and their properties. Here, we explore whether a toy model of the Higgs-Yukawa sector of the Standard Model is compatible with…

High Energy Physics - Theory · Physics 2016-11-15 Astrid Eichhorn , Aaron Held , Jan M. Pawlowski

We highlight the fact that the lack of scale invariance in the gravitational field equations of General Relativity results from the underlying assumption that the appropriate scale for the gravitational force should be linked to the atomic…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Robin Booth

The SMEFT provides a general framework to search for new physics beyond the current reach of direct detection. One such form of new physics is quantum gravity. Based on dimensional analysis, one would expect the prediction that the…

High Energy Physics - Phenomenology · Physics 2024-07-18 Lydia Brenner , Abhishek Chikkaballi , Astrid Eichhorn , Shouryya Ray

In the context of Quantum Cosmology and the Wheeler-DeWitt equation we investigate the possible effects of a non semiclassical wave-function of the universe on the evolution of the inflationary perturbations. These are associated with the…

General Relativity and Quantum Cosmology · Physics 2018-06-20 A. Y. Kamenshchik , A. Tronconi , T. Vardanyan , G. Venturi

The idea of gauge theories of gravity predicts that there should exist not only the massless graviton but also massive particles carrying the gravitational force. We study the cosmology in a quadratic gravity with dynamical torsion where…

High Energy Physics - Theory · Physics 2020-06-17 Katsuki Aoki , Shinji Mukohyama

We give a detailed presentation of a recently proposed mechanism of generating the energy scale of inflation by loop effects in quantum cosmology. We discuss the quantum origin of the early inflationary Universe from the no-boundary and…

General Relativity and Quantum Cosmology · Physics 2011-08-17 A. O. Barvinsky , A. Yu. Kamenshchik , I. V. Mishakov

Based on the ultraviolet asymptotic freedom of nonlocal quantum gravity, we show that the trans-Planckian energy regime is unattainable in laboratory experiments. As physical implications, it turns out that the violation of causality,…

High Energy Physics - Theory · Physics 2020-09-10 Fabio Briscese , Leonardo Modesto

The canonical (CQG) and asymptotically safe (ASQG) approach to quantum gravity share to be both non-perturbative programmes. However, apart from that they seem to differ in several aspects such as: 1. Signature: CQG is Lorentzian while ASQG…

High Energy Physics - Theory · Physics 2024-04-30 Thomas Thiemann