123 citations · 659 across the 33 of their papers we have counts for
33 papers
A scaling non-compact QCD axion
Georgios K. Karananas, Mikhail Shaposhnikov
We present a dynamical mechanism for the erasure of inflationary isocurvature perturbations of the non-compact QCD axion. The key ingredient is an early-time runaway exponential po…
QCD axion from broken scale symmetry
Georgios K. Karananas, Mikhail Shaposhnikov
A consistent non-compact axion cosmology requires a non-periodic field, an effective field theory valid sufficiently above the inflationary scale, and a small non-QCD contribution…
Three-form lifting of dilaton flat direction without and with gravity
Georgios K. Karananas
Spontaneous scale symmetry breaking is commonly associated with a flat direction in the action. We show that this need not be so if the dilaton is coupled to a three-form field in…
A non-compact QCD axion
Georgios K. Karananas, Mikhail Shaposhnikov, Sebastian Zell
We investigate the cosmology of an axion that is fundamentally non-compact. During inflation, fluctuations of the effectively massless field populate many QCD vacua, thereby evadin…
Higgs inflation in Weyl-invariant Einstein-Cartan gravity
Georgios K. Karananas, Mikhail Shaposhnikov
In this short note we analyze the inflationary dynamics in Weyl-invariant Einstein-Cartan gravity coupled to the Standard Model of particle physics. We take the axion-like particle…
On the Gravitational Origin of the QCD Axion
Georgios K. Karananas, Mikhail Shaposhnikov, Sebastian Zell
Gravity can give rise to (pseudo)scalar fields, for instance due to torsion. In particular, axions of gravitational origin have been proposed as a minimal and compelling solution t…
The particle spectra of parity-violating theories: A less radical approach and an upgrade of PSALTer
Will Barker, Georgios K. Karananas, Haochen Tu
Due to computational barriers, the effects of parity violation have so far been grossly neglected in gravitational model-building, leading to a serious gap in the space of prior mo…
Geometrical origin of inflation in Weyl-invariant Einstein-Cartan gravity
Georgios K. Karananas
It is shown that the scalar degree of freedom built-in in the quadratic Weyl-invariant Einstein-Cartan gravity can drive inflation and with predictions in excellent agreement with…
The particle content of (scalar curvature) metric-affine gravity
Georgios K. Karananas
Linearizing metric-affine~(scalar curvature) gravity -- an ``umbrella'' theory that includes as special cases the metrical, Einstein-Cartan, and Weyl quadratic models -- on top…
The particle content of gravity revisited
Georgios K. Karananas
Studying the spectrum of (pure) gravity on Minkowski background inevitably results into a Catch-22: any consistent interpretation of its particle dynamics dictates that no ac…
Weyl-invariant Einstein-Cartan gravity: unifying the strong CP and hierarchy puzzles
Georgios K. Karananas, Mikhail Shaposhnikov, Sebastian Zell
We show that the minimal Weyl-invariant Einstein-Cartan gravity in combination with the Standard Model of particle physics contains just one extra scalar degree of freedom (in addi…
The geometry of inflationary observables: lifts, flows, equivalence classes
Georgios K. Karananas, Marco Michel, Javier Rubio
The Eisenhart lift allows to formulate the dynamics of a scalar field in a potential as pure geodesic motion in a curved field-space manifold involving an additional fictitious vec…
Scale invariant Einstein-Cartan gravity and flat space conformal symmetry
Georgios K. Karananas, Mikhail Shaposhnikov, Sebastian Zell
We find the conditions under which scale-invariant Einstein-Cartan gravity with scalar matter fields leads to an approximate conformal invariance of the flat space particle theory…
Field redefinitions, perturbative unitarity and Higgs inflation
Georgios K. Karananas, Mikhail Shaposhnikov, Sebastian Zell
For inflation driven by the Higgs field coupled non-minimally to gravity, we study the cutoff energy scale above which perturbation theory breaks down. Employing the metric formula…
More on the operator-state map in non-relativistic CFTs
Georgios K. Karananas, Alexander Monin
We propose an algebraic construction of the operator-state correspondence in non-relativistic conformal field theories by explicitly constructing an automorphism of the Schrödinger…
Scale and Weyl Invariance in Einstein-Cartan Gravity
Georgios K. Karananas, Mikhail Shaposhnikov, Andrey Shkerin +1
We show how Einstein-Cartan gravity can accommodate both global scale and local scale (Weyl) invariance. To this end, we construct a wide class of models with nonpropagaing torsion…
Matter matters in Einstein-Cartan gravity
Georgios K. Karananas, Mikhail Shaposhnikov, Andrey Shkerin +1
We study scalar, fermionic and gauge fields coupled nonminimally to gravity in the Einstein-Cartan formulation. We construct a wide class of models with nondynamical torsion whose…
Islands in Linear Dilaton Black Holes
Georgios K. Karananas, Alex Kehagias, John Taskas
We derive a novel four-dimensional black hole with planar horizon that asymptotes to the linear dilaton background. The usual growth of its entanglement entropy before Page's time…
Aspects of spontaneous breaking of conformal invariance in the Fishnet CFT
Georgios K. Karananas
I will discuss spontaneous conformal symmetry breaking in the strongly -deformed limit of the supersymmetric Yang-Mills theory known as~\emph{Fishnet Conformal Fi…
Spontaneous Conformal Symmetry Breaking in Fishnet CFT
Georgios K. Karananas, Vladimir Kazakov, Mikhail Shaposhnikov
Quantum field theories with exact but spontaneously broken conformal invariance have an intriguing feature: their vacuum energy (cosmological constant) is equal to zero. Up to now,…
Scale-invariant alternatives to general relativity. III. The inflation--dark-energy connection
Santiago Casas, Georgios K. Karananas, Martin Pauly +1
We discuss the cosmological phenomenology of biscalar-tensor models displaying a maximally symmetric Einstein-frame kinetic sector and constructed on the basis of scale symmetry an…
On the strong-CP problem and its axion solution in torsionful theories
Georgios K. Karananas
Gravitational effects may interfere with the axion solution to the strong-CP problem. We point out that gravity can potentially provide a protection mechanism against itself, in th…
Small-scale structure from neutron dark decay
Georgios K. Karananas, Alexis Kassiteridis
It was recently proposed that the disagreement in the experimental measurements of the lifetime of the neutron might be eradicated if the neutron decays to particles responsible fo…
CFT data and spontaneously broken conformal invariance
Georgios K. Karananas, Mikhail Shaposhnikov
We derive consistency conditions for the CFT data, which systems with exact but spontaneously broken conformal invariance must satisfy.