The conjecture by Mavromatos and Sarkar that a PT-symmetric phase plays a role in understanding singular renormalisation group (RG) flows for a Chern-Simons ...
Ultralight scalar dark matter may couple to the Standard Model through dimension-five operators that contain the field-strength tensors of the gauge interact...
Computing the gravitational effective action provides a direct route to charting the landscape of admissible black hole spacetimes and their alternatives, co...
According to long-standing folklore, spacetime at Planckian distances bears no resemblance to the spacetime of classical general relativity, but instead is s...
We present a Lorentzian quantum gravity study coupled to a template matter sector with gauge fields, scalars and fermions. Provided quantum gravity offers an...
Geons are hypothetical objects from self-bound gravity quanta. They are potential candidates for dark matter, but could also be considered (quantum) black ho...
I will present our recent proposal of a renormalization group flow equation for a functional that generates S-matrix elements and which captures similarities...
We present the first fully self-consistent computation of the graviton spectral function in (asymptotically safe) quantum gravity, using the spectral renorma...
In this talk, I will explore the phenomenological consequences of Quantum Scale symmetry in the matter sector of the Standard Model with Asymptotically Safe ...
We present the first complete next-to-leading-order analysis of a Yukawa system within the framework of asymptotically safe quantum gravity. Our results are ...
Recent work has revealed that extremal Kerr black holes may exhibit a sensitivity to higher-derivative corrections to Einstein’s equations, displaying singul...
Lorentzian path integrals exhibit profoundly different properties from Euclidean ones due to the oscillatory integrand which weighs different configurations ...
We investigate β-functions of quantum gravity using dimensional regularisation. In contrast to minimal subtraction, a non-minimal renormalisation scheme is e...
CDT is a lattice theory of quantum gravity. It is shown how to identify the IR and the UV limit of this lattice theory with similar FRG limits.
We compute the asymptotic safety landscape stemming from ultraviolet-complete photon-graviton flows in a field theoretic setup, and we confront it with the w...
The asymptotically safe (ASQG) and the canonical (CQG) approach to quantum gravity share to be both non-perturbative programmes. However, apart from that the...
For more than a decade, we are used to the idea that evaluating Wetterich’s equation for polynomial f(R)-truncations yields 3 relevant directions. Moreover, ...
I start from the assumption that the theory of gravity can be formulated in terms of 4-dimensional action, and there are only 2 graviton polarization states,...
Asymptotic safety is a promising mechanism for obtaining a consistent and predictive quantum theory for gravity. The ADM formalism allows to introduce a (Euc...
We argue that the well-known beta functions of quadratic gravity do not correspond to the physical dependence of scattering amplitudes on external momenta, a...
Field transformations for the quantum effective action lead to different pictures of a given physical situation, as describing a given evolution of the unive...
Asymptotic safety is a powerful mechanism for obtaining a consistent and predictive quantum field theory beyond the realm of perturbation theory. It hinges o...
We analyse the renormalisation group flow of quantum gravity at sixth order in the derivative expansion within the background field approximation. Non-linear...
We have constructed relativistic versions of Luttinger fermions in analogy to effective low-energy degrees of freedom of non-relativistic solid-state systems...
We discuss general momentum-dependent field redefinitions in the context of quantum-gravitational scattering amplitudes in general, and Asymptotic Safety in ...
If the metric is chosen to depend exponentially on the conformal factor, and if one works in a gauge where the conformal factor has the wrong sign propagator...
Many phase transitions can be understood as the spontaneous breaking of a global symmetry of the microscopic system. This is well captured within the framewo...
Spacetime singularities as predicted by general relativity signal the breakdown of our classical description of gravity and are expected to be absent in a fu...
We investigate whether quantum gravity fluctuations can break chiral symmetry for fermions that are charged under a U(1) and an SU(Nc) gauge symmetry, and th...
Recently, together with Drago, Pinamonti, and Rejzner, I introduced a functional Renormalization Group (RG) equation to explore non-perturbative and covarian...
We revisit the dynamical generation of an arbitrarily small neutrino Yukawa coupling in the Standard Model with trans-Planckian asymptotic safety and apply t...
In this seminar, I will explore possible connections between the causal sets and asymptotic safety approaches to quantum gravity. In the first part of the se...
I will discuss how regular black hole spacetimes are obtained from an effective Lagrangian for Quantum Einstein Gravity. The interior matter is modeled as a ...
The seminar will revolve around the analysis of the conformal sector of Quantum Einstein Gravity with an improvement due to the study of the role of the anom...
Exploring quantum corrections to black hole geometries might offer a unique opportunity for observationally testing the asymptotic safety scenario in quantum...
The gravitational asymptotic safety program envisions a high-energy completion of gravity based on a non-Gaussian renormalization group fixed point. A key st...
We study the mechanism of chiral symmetry breaking for fermionic systems in a gravitational background with curvature and torsion. The analysis is based on a...
The Causal Dynamical Triangulations (CDT) model is a background-independent and diffeomorphism-invariant approach to quantum gravity that provides a lattice ...
We discuss higher-loop studies of beta functions and their zeros in various quantum field theories. We focus mainly on infrared-free theories. Some calculati...
In this talk, we investigate spectral functions of matter-gauge theories that are asymptotically free in the ultraviolet and display a Banks-Zaks conformal f...
We explore the properties of a simple renormalizable shift symmetric model with a higher deriva- tive kinetic energy and quartic derivative coupling, that ca...
I will talk about our latest paper whose abstract is: “New physics beyond the Standard Model can give rise to stochastic gravitational wave backgrounds, for ...
The proton lifetime is technically a low-energy measurement, the proton’s rest mass being only 1 GeV. However, it is also extraordinarily large: 21 orders of...
In this talk, I will discuss the quantum improvement of black hole solutions in the context of asymptotic safety. We propose that the consistency of the firs...
Horndeski gravity is a popular contender for a phenomenological model of dynamical dark energy, and as such subject to observational constraints. My colleagu...
We discuss the geometrization of entire evolution histories by means of a single, (d+1)-dimensional manifold furnished with a fixed (pseudo-) Riemannian stru...
The weak-gravity bound has been discovered in several asymptotically safe gravity-matter systems. It limits the strength of gravitational fluctuations that a...
We propose a new method to account for quantum-gravitational effects in cosmological and black hole spacetimes. At the core of our construction is the “decou...
We investigate axion-like particles (ALPs) in the context of asymptotically safe gravity-matter systems. The ALP-photon interaction, which facilitates experi...
Wetterich’s equation provides a powerful tool for investigating the existence and universal properties of renormalization group fixed points exhibiting quant...
We present a comprehensive non-perturbative study of the phase structure of the asymptotically safe Standard Model. The physics scales included range from th...
Resumming quantum fluctuations at the level of the gravitational path integral is expected to result in non-local effective actions and thus in a non-trivial...
In gauge-Yukawa systems embedded in the framework of trans-Planckian asymptotic safety we discuss the dynamical generation of arbitrarily small Yukawa coupli...
We derive new functional renormalisation group flows for quantum gravity, in any dimension. The key new achievement is that the equations apply for any theor...
The SU(N) Yang-Mills theory in ℝ4×S1 spacetime is studied as a simple toy model of Gauge-Higgs unification. The theory is perturbatively nonrenormalizable bu...
Path integrals and the Wilsonian renormalization group provide two complementary computational tools for investigating continuum approaches to quantum gravit...
We discuss the renormalisation group flow of all essential couplings of quantum gravity coupled to a shift-symmetric scalar field at fourth order in the deri...
We propose testing the paradigm of asymptotically safe gravity using swampland conjectures. As a first step in this direction, we explore the infrared regime...
We apply the new quantization scheme outlined in M. Becker and M. Reuter, Phys. Rev. D 102, 125001 (2020), to explore the influence which quantum vacuum fluc...
The Wetterich equation governs the renormalization flow of the effective action under the scaling of an IR cutoff. In this talk, I introduce a generalization...
In this talk, I will explore the effect of quantum gravity on matter couplings within a Renormalization Group framework. In particular, I will focus on resul...
The scaling solution of the functional flow in dilaton quantum gravity leads to highly predictive cosmology. Inflation and quintessence can both be described...
A spatial variant of the Functional Renormalization Group (FRG) is introduced on (Lorentzian signature) globally hyperbolic spacetimes. Through its perturbat...
A basic calculation in QFT is the construction of the Yukawa potential from a tree-level scattering amplitude. In the massless limit, this reproduces the 1/r...
One of the greatest issues for a quantum theory of gravitation is how to generalise the notion of local observable quantities. A viable approach is to constr...
In this talk I will describe how we can derive general properties of the fixed-point solutions to the flow equations in the f(R) approximation using a family...
U(1)’ extensions of the SM with generation-dependent couplings to quarks and leptons are a popular explanation of anomalies in rare B-decays, such as the R_K...
In this work we use the Wetterich equation for the effective average action to investigate the RG flow of gravity supplemented by a real scalar field. We giv...
We compute non-perturbative flow equations for the couplings of quantum gravity in fourth order of a derivative expansion. The gauge invariant functional flo...
We present the first direct and non-perturbative computation of the graviton spectral function in quantum gravity. This is achieved with the help of a novel ...
The propagator stores important information about the causality and unitarity of a theory, and is related to the spectral function, if it exists. Studying th...
We use the framework of asymptotic safety above the Planck scale to constrain the parameter space of simple models of new physics that can accommodate the me...
In this talk, we introduce the weak-gravity bound for scalar-gravity systems within the asymptotic-safety paradigm. The weak-gravity bound arises when gravit...
The non-perturbative renormalisation of quantum gravity is investigated allowing for the metric to be reparameterised along the RG flow, such that only the e...
We use the generalised flow of the Effective average action which incorporates field redefinitions along the RG flow. This equation allows for the implementa...
Black holes are vital for a consistent description of gravitational wave events as well as the recent image of the Event Horizon Telescope. However, black ho...
There are reasons to believe that extensions to the Standard Model that tend to lower the Higgs mass are phenomenologically attractive. (For one thing, it wo...
Causal sets are a theory that encodes space-time through the causal relations between events. This leads to a fundamentally Lorentzian, discrete, formulation...
We present a general framework to systematically study the derivative expansion of asymptotically safe quantum gravity. It is based on an exact decoupling an...
We reconstruct the Lorentzian graviton propagator in asymptotically safe quantum gravity from Euclidean data. The reconstruction is applied to both the dynam...
Higher-derivative corrections to cosmological effective actions in string theory are largely constrained by T-duality, but have been computed hitherto only t...
In this talk we discuss the most recent step in an approach to finding the continuum limit of quantum gravity using the exact renormalization group and the c...
We study the phase diagram of 5-dimensional SU(2) Yang-Mills theory on the lattice. We consider two extensions of the fundamental plaquette Wilson action in ...
A suitable candidate for a UV-complete quantum theory of gravity needs to be compatible with the existence of chiral fermions. Studies of quantum fields in c...
We consider a free scalar field on Euclidean dynamical triangulations. By studying the 1-particle and 2-particle correlation functions, we extract the bindi...
Geometries describing static non-singular black holes have been obtained in suitable limits of various quantum gravity frameworks, including asymptotic safet...
A number of approaches to four-dimensional quantum gravity, such as loop quantum gravity and holography, situate areas as their fundamental variables. These ...
The question whether global symmetries can be realized in quantum-gravity-matter-systems has far-reaching phenomenological consequences. During my talk I wil...
We consider a class of models for dynamical dark energy: we construct a general effective dynamics for diffeomorphisms of spacetime, in a fixed external metr...
In this talk, the fixed point structure of asymptotically safe quantum gravity is tested for actions containing squares of the Riemann tensor and the Ricci s...
According to the asymptotic-safety conjecture, a (non-perturbatively) renormalizable quantum field theory of gravity could be constructed based on the existe...
I will describe how the framework of asymptotically safe quantum gravity can be employed to derive novel predictions for some well-known new physics solution...
In this talk the fixed point structure of gravity-fermion systems on a curved background spacetime will be discussed using the functional renormalization gro...
High-energy completeness of quantum electrodynamics (QED) can be induced by an interacting ultraviolet fixed point of the renormalization flow. We provide ev...
Asymptotic safety might have significant predictive implications for dark matter models. I illustrate this in a toy model for the visible Higgs-Yukawa sector...
Application of the Weinberg’s conditions of asymptotic safety to amplitudes and not to couplings of the effective action can help to uniquely define the runn...
We study the quantum gravitational system coupled to a charged scalar, Dirac fermions, and electromagnetic fields. We use the “exact” or “functional” renorma...
I will discuss a new flow equation for the Wilsonian effective action based on a gauge invariant UV regularisation of gauge theories and gravity. The regular...
We apply the functional renormalization group equation to a massive Fierz–Pauli action in curved space and find that, even though a massive term is a modif...
Determining the structure of the UV-critical hypersurface, spanned by renormalization group trajectories enjoying asymptotic safety, is a highly complex prob...
In this talk I will present the analysis of a dually-weighted Matrix Model which implements a preferred foliation in its dual-graph. By using the FRGE, we st...
Recent studies in the context of asymptotically safe quantum gravity imply that scalar quartic couplings and scalar masses vanish above the Planck scale due ...
The derivative expansion (DE) is the most commonly used approximation scheme of Wilson’s renormalization group (RG), at least when it is formulated in terms ...
We explore 4d gauge-Yukawa theories with weakly coupled UV fixed points. Using Majorana fermions, new families of theories with perturbatively exact asymptot...
We search for an extension of the Standard Model that contains a viable dark matter candidate and that can be embedded into a fundamental, asymptotically saf...
Constraining quantum gravity from observations is a challenge. In this seminar, I explore the idea that the interplay of quantum gravity with matter could be...
Taking manifest invariance under both gauge symmetry and diffeomorphisms as a guiding principle physical objects are constructed for Yang-Mills-Higgs theory ...
The effective action is a powerful tool for studying the non-perturbative behaviour of quantum field theories. In this talk, we will revisit the derivation ...
By definition, form factors capture the momentum dependence of a theory’s n-point function. For example, they may encode corrections to the propagation of fi...
In my talk, I explore the question why our universe is four dimensional from an asymptotically safe vantage point. I present indications that asymptotically ...
We construct a black-hole spacetime which includes the running of the gravitational coupling in a self-consistent way. Starting from a classical Schwarzschil...
The effect of gravitational fluctuations on the quantum effective potential for scalar fields is a key ingredient for predictions of the mass of the Higgs bo...
The Effective Average Action is a form of effective action which depends on a cutoff scale suppressing the contribution of low momentum modes in the function...
We consider geometric operators, such as the geodesic length and the volume of hypersurfaces, in the context of the Asymptotic Safety scenario for quantum gr...
After a short introduction on how to set up a foliation in a covariant language, I will use this formalism to investigate the RG flow on foliated spacetimes....
There are many proposals how to extend the Standard Model, designed to deal with its fundamental inconsistencies. Since no new particles have been detected e...
I derive an exact RG equation for the Wilsonian Effective Action, that is essentially a background field (and gauge invariant) version of the Polchinski equa...
This presentation aims at giving our new advance on the functional renormalization group applied to tensorial group field theory. It is based on a serie of o...
We explore whether the phase diagram of tensor models could feature a pregeometric, discrete and a geometric, continuum phase for the building blocks of spac...
We explore asymptotic safety of gravity-matter systems, discovering indications for a near-perturbative nature of these systems in the ultraviolet. Our resul...
We explain how the quantum gravity regime associated with Asymptotic Safety may set the initial conditions for a consistent cosmological evolution, from the ...
Asymptotically safe extensions of the Standard Model have been searched for by adding vector-like fermions charged under the Standard Model gauge group and h...
We study the dependence on field parametrization in the context of the Asymptotic Safety scenario. The investigation is performed with the f(R)-truncation fo...
Recent results based on renormalization group approaches to Quantum Gravity suggest that the Newton’s and Cosmological constants should be treated as dynamic...
We investigate the asymptotic safety scenario for a scalar-gravity system. This system contains two avatars of the dynamical Newton coupling, a gravitational...
I will present a new method to constrain the quantum effective action of gravity, inspired by recent results from causal dynamical triangulations (CDT). Afte...
We will discuss the instanton dynamics of asymptotically safe and free quantum field theories featuring respectively controllable ultraviolet and infrared fi...
Gravitational catalysis expresses an interplay between the curvature of the spacetime and fluctuation-induced mass generation of quantum matter. I will show ...
In this talk, we will investigate asymptotic safety of a toy model of a singlet-scalar extension of the Higgs sector including two real scalar fields under t...
We use the functional renormalization group equation for the effective average action to study the non-Gaussian renormalization group fixed points (NGFPs) ar...
We compute the one-loop effective action in unimodular gravity, starting from two different classical formulations of the theory. We find that the effective ...