All Outputs (70)

Boson star superradiance (2024)
Journal Article

Recently, it has been realized that in some systems internal space rotation can induce energy amplification for scattered waves, similar to rotation in real space. In particularly, it has been shown that energy extraction is possible for a Q-ball, a... Read More about Boson star superradiance.

Ringdowns for black holes with scalar hair: The large mass case (2024)
Journal Article

Deviations from general relativity can alter the quasinormal mode (QNM) ringdown of perturbed black holes. It is known that a shift-symmetric (hence massless) scalar can only introduce black hole hair if it couples to the Gauss-Bonnet invariant, in w... Read More about Ringdowns for black holes with scalar hair: The large mass case.

Quantum corrected Q-ball dynamics (2024)
Journal Article

The physics of individual Q-balls and interactions between multiple Q-balls are well-studied in classical numerical simulations. Interesting properties and phenomena have been discovered, involving stability, forces, collisions and swapping of charge... Read More about Quantum corrected Q-ball dynamics.

Q-Ball Superradiance (2023)
Journal Article

Q-balls are nontopological solitons that coherently rotate in field space. We show that these coherent rotations can induce superradiance for scattering waves, thanks to the fact that the scattering involves two coupled modes. Despite the conservatio... Read More about Q-Ball Superradiance.

Clockwork cosmology (2023)
Journal Article

The higher order generalisation of the clockwork mechanism to gravitational interactions provides a means to generate an exponentially suppressed coupling to matter from a fundamental theory of multiple interacting gravitons, without introducing larg... Read More about Clockwork cosmology.

Vertex functions and their flow equations from the 2PI effective action (2022)
Journal Article

By exploiting the convexity of the two-particle-irreducible effective action, we describe a procedure for extracting n-point vertex functions. This procedure is developed within the context of a zero-dimensional ‘quantum field theory’ and subsequentl... Read More about Vertex functions and their flow equations from the 2PI effective action.

Optimisation of Thimble simulations and quantum dynamics of multiple fields in real time (2022)
Journal Article

We apply the Generalised Thimble approach to the computation of exact path integrals and correlators in real-time quantum field theory. We first investigate the details of the numerical implementation and ways of optimizing the algorithm. We subseque... Read More about Optimisation of Thimble simulations and quantum dynamics of multiple fields in real time.

Charge-swapping Q-balls in a logarithmic potential and Affleck-Dine condensate fragmentation (2022)
Journal Article

We study charge-swapping Q-balls, a kind of composite Q-ball where positive and negative charges co-exist and swap with time, in models with a logarithmic potential that arises naturally in supersymmetric extensions of the Standard Model. We show tha... Read More about Charge-swapping Q-balls in a logarithmic potential and Affleck-Dine condensate fragmentation.

Gravitational collapse of quantum fields and Choptuik scaling (2022)
Journal Article

Gravitational collapse into a black hole has been extensively studied with classical sources. We develop a new formalism to simulate quantum fields forming a black hole. By choosing a convenient coherent state, this formalism taps into well-establish... Read More about Gravitational collapse of quantum fields and Choptuik scaling.

Benchmarking regulator-sourced 2PI and average 1PI flow equations in zero dimensions (2021)
Journal Article

We elucidate the regulator-sourced 2PI and average 1PI approaches for deriving exact flow equations in the case of a zero dimensional quantum field theory, wherein the scale dependence of the usual renormalisation group evolution is replaced by a sim... Read More about Benchmarking regulator-sourced 2PI and average 1PI flow equations in zero dimensions.

Erratum: Alternative flow equation for the functional renormalization group [Phys. Rev. D 100, 101702(R) (2019)] (2021)
Journal Article

We correct the functional identity reported in our paper for the inverse two-point function, as obtained from the 2PI effective action. The original conclusions are otherwise unaffected. The 2PI effective action is convex with respect to the variable... Read More about Erratum: Alternative flow equation for the functional renormalization group [Phys. Rev. D 100, 101702(R) (2019)].

Gravitational collapse with quantum fields (2021)
Journal Article

Gravitational collapse into a black hole has been extensively studied with classical sources. We develop a new formalism to simulate quantum fields forming a black hole. This formalism utilizes well-established techniques used for classical collapse... Read More about Gravitational collapse with quantum fields.

Charge-Swapping Q-balls and Their Lifetimes (2021)
Journal Article

For scalar theories accommodating spherically symmetric Q-balls, there are also towers of quasi-stable composite Q-balls, called charge swapping Q-balls (CSQs). We investigate the properties, particularly the lifetimes, of these long-lived CSQs in 2+... Read More about Charge-Swapping Q-balls and Their Lifetimes.

Dipole radiation and beyond from axion stars in electromagnetic fields (2021)
Journal Article

We investigate the production of photons from coherently oscillating, spatially localized clumps of axionic fields (oscillons and axion stars) in the presence of external electromagnetic fields. We delineate different qualitative behaviour of the pho... Read More about Dipole radiation and beyond from axion stars in electromagnetic fields.

Deconstructing higher order clockwork gravity (2021)
Journal Article

We consider the higher order clockwork theory of gravitational interactions, whereby a number of gravitons are coupled together with TeV strength, but nevertheless generate a Planck scale coupling to matter without the need for a dilaton. It is shown... Read More about Deconstructing higher order clockwork gravity.

Statistics on Lefschetz thimbles: Bell/Leggett-Garg inequalities and the classical-statistical approximation (2021)
Journal Article

Inspired by Lefschetz thimble theory, we treat Quantum Field Theory as a statistical theory with a complex Probability Distribution Function (PDF). Such complex-valued PDFs permit the violation of Bell-type inequalities, which cannot be violated by a... Read More about Statistics on Lefschetz thimbles: Bell/Leggett-Garg inequalities and the classical-statistical approximation.

Simulations of a bubble wall interacting with an electroweak plasma (2021)
Journal Article

We perform large-scale real-time simulations of a bubble wall sweeping through an out-of-equilibrium plasma. The scenario we have in mind is the electroweak phase transition, which may be first order in extensions of the Standard Model, and produce s... Read More about Simulations of a bubble wall interacting with an electroweak plasma.

Classical decay rates of oscillons (2020)
Journal Article

Oscillons are extremely long-lived, spatially-localized field configurations in real-valued scalar field theories that slowly lose energy via radiation of scalar waves. Before their eventual demise, oscillons can pass through (one or more) exceptiona... Read More about Classical decay rates of oscillons.

Black holes in self-tuning cubic Horndeski cosmology (2020)
Journal Article

Observations of neutron star mergers in the late Universe have given significant restrictions to the class of viable scalar-tensor theories. In this paper we construct black holes within the “self-tuning” class of this restricted set, whereby the bar... Read More about Black holes in self-tuning cubic Horndeski cosmology.

Alternative flow equation for the functional renormalization group (2019)
Journal Article

We derive an alternative to the Wetterich-Morris-Ellwanger equation by means of the two-particle irreducible (2PI) effective action, exploiting the method of external sources due to Garbrecht and Millington. The latter allows the two-point source of... Read More about Alternative flow equation for the functional renormalization group.