109 citations · 409 across the 21 of their papers we have counts for
22 papers
Catastrophic Inflation in the Axiverse
Naomi Gendler, Oliver Janssen, Matthew Kleban +1
In the landscape of compactifications of type IIB string theory on O3/O7 orientifolds of Calabi--Yau threefolds, we identify regions of the axion potential in specific geometries t…
A gentle introduction to the cosmological multiverse
Oliver Janssen
We give an introduction to the cosmological multiverse, aimed at an audience of artists. We discuss general relativity -- our modern theory of gravity -- and the cosmological const…
An ode to instantons
Oliver Janssen, Joel Karlsson, Flavio Riccardi +1
We present a formalism for semiclassical time evolution in quantum mechanics, building on a century of work. We identify complex saddle points in real time, real saddle points in c…
Allowable complex metrics and the gravitational index of AdS black holes
Pietro Benetti Genolini, Oliver Janssen, Sameer Murthy
We discuss the Kontsevich-Segal-Witten criterion for the allowability of complex metrics, in the context of the gravitational path integral that calculates the supersymmetric index…
The Kontsevich-Segal Criterion in the No-Boundary State Constrains Anisotropy
Thomas Hertog, Oliver Janssen, Joel Karlsson
We show that the Kontsevich-Segal-Witten (KSW) criterion applied to the no-boundary state constrains anisotropic deformations of de Sitter space. We consider squashed and $S^…
KSW criterion in large field models
Oliver Janssen
We extend the analytic description of complex no-boundary solutions in the context of inflation to large field models. We discuss the Kontsevich-Segal-Witten (KSW) criterion and fi…
Axion minima in string theory
Naomi Gendler, Oliver Janssen, Matthew Kleban +2
We study the landscape of axion theories in compactifications of type IIB string theory on orientifolds of Calabi-Yau threefolds. In a sample of approximately 400,000 geometries we…
The Kontsevich-Segal Criterion in the No-Boundary State Constrains Inflation
Thomas Hertog, Oliver Janssen, Joel Karlsson
We show that the Kontsevich-Segal (KS) criterion, applied to the complex saddles that specify the semiclassical no-boundary wave function, acts as a selection mechanism on inflatio…
Positivity bounds on effective field theories with spontaneously broken Lorentz invariance
Paolo Creminelli, Oliver Janssen, Leonardo Senatore
We derive positivity bounds on EFT coefficients in theories where boosts are spontaneously broken. We employ the analytic properties of the retarded Green's function of conserved c…
Gravity as an ensemble and the moment problem
Oliver Janssen, Mehrdad Mirbabayi, Peter Zograf
If a bulk gravitational path integral can be identified with an average of partition functions over an ensemble of boundary quantum theories, then a corresponding moment problem ca…
Low-temperature entropy in JT gravity
Oliver Janssen, Mehrdad Mirbabayi
For ensembles of Hamiltonians that fall under the Dyson classification of random matrices with , the low-temperature mean entropy can be shown to vanish as $\langle…
Decoherence: A Numerical Study
Chris Nagele, Oliver Janssen, Matthew Kleban
We study quantum decoherence numerically in a system consisting of a relativistic quantum field theory coupled to a measuring device that is itself coupled to an environment. The m…
Slow-roll approximation in quantum cosmology
Oliver Janssen
In minimally coupled scalar field theories with a potential of the slow-roll type, we give a detailed description of the complex -symmetric solutions to Einstein's equations…
The no-boundary proposal in biaxial Bianchi IX minisuperspace
Oliver Janssen, Jonathan J. Halliwell, Thomas Hertog
We implement the no-boundary proposal for the wave function of the universe in an exactly solvable Bianchi IX minisuperspace model with two scale factors. We extend our earlier wor…
The Axidental Universe
Thomas C. Bachlechner, Kate Eckerle, Oliver Janssen +1
Theories with several hundred axion fields have enormous numbers of distinct meta-stable minima. A small fraction of these local minima have vacuum energy compatible with current m…
Axion Landscape Cosmology
Thomas C. Bachlechner, Kate Eckerle, Oliver Janssen +1
We study the cosmology of complex multi-axion theories. With O(100) fields and GUT scale energies these theories contain a vast number of vacua, inflationary trajectories and a nat…
Damped perturbations in the no-boundary state
Juan Diaz Dorronsoro, Jonathan J. Halliwell, James B. Hartle +3
We evaluate the no-boundary path integral exactly in a Bianchi IX minisuperspace with two scale factors. In this model the no-boundary proposal can be implemented by requiring one…
Systematics of Aligned Axions
Thomas C. Bachlechner, Kate Eckerle, Oliver Janssen +1
We describe a novel technique that renders theories of axions tractable, and more generally can be used to efficiently analyze a large class of periodic potentials of arbitrary…
The Real No-Boundary Wave Function in Lorentzian Quantum Cosmology
Juan Diaz Dorronsoro, Jonathan J. Halliwell, James B. Hartle +2
It is shown that the standard no-boundary wave function has a natural expression in terms of a Lorentzian path integral with its contour defined by Picard-Lefschetz theory. The wav…
Axions of Evil
Thomas C. Bachlechner, Kate Eckerle, Oliver Janssen +1
We provide a systematic framework for theories of multiple axions. We discover a novel type of "alignment" that renders even very complex theories analytically tractable. Theories…
Sharp Predictions from Eternal Inflation Patches in D-brane Inflation
Thomas Hertog, Oliver Janssen
We numerically generate the six-dimensional landscape of D3-brane inflation and identify patches of eternal inflation near sufficiently flat inflection points of the potential. We…
Phase Diagram of Dynamical Twisted Mass Wilson Fermions at Finite Isospin Chemical Potential
Oliver Janssen, Mario Kieburg, K. Splittorff +2
We consider the phase diagram of twisted mass Wilson fermions of two-flavor QCD in the parameter space of the quark mass, the isospin chemical potential, the twist angle and the la…