254 citations · 1.8k across the 33 of their papers we have counts for
33 papers
Bumpy inflation from explosive particle production
Kaloian D. Lozanov, Xavier Pritchard, Misao Sasaki
We present a first-principles derivation of an effective inflaton potential with a bumpy feature. We consider the coupling of a spectator field χto the inflaton ϕsuch that χis mass…
Constraining the inflaton potential with gravitational waves from oscillons
Kaloian D. Lozanov, Misao Sasaki, Jan Tränkle
Under certain conditions, the oscillating inflaton condensate filling the Universe after inflation can fragment and form so-called oscillons. These long-lived soliton-like field co…
Metal-insulator transition in a CuO chain created by Kondo interaction
Todor M. Mishonov, Albert M. Varonov, Kaloian D. Lozanov
Over twenty years ago Alexei Abrikosov [A.A. Abrikosov, Metal-insulator transition in layered cuprates (SDW model), Physica C: Supercond. Vol. 391, 2, 147-159 (2003)] considered th…
Crunch from AdS bubble collapse in unbounded potentials
Kaloian D. Lozanov, Misao Sasaki
We consider a scalar field theory with a Minkowski false vacuum and an unbounded (or very deep) true vacuum. We show compelling evidence that an AdS bubble of vanishing total energ…
Axion-like Universal Gravitational Wave Interpretation of Pulsar Timing Array Data
Kaloian D. Lozanov, Shi Pi, Misao Sasaki +2
Formation of cosmological solitons is generically accompanied by production of gravitational waves (GWs), with a universal GW background expected at frequency scales below that of…
Universal Gravitational Waves from Interacting and Clustered Solitons
Kaloian D. Lozanov, Misao Sasaki, Volodymyr Takhistov
Causal soliton formation (e.g. oscillons, Q-balls) in the primordial Universe is expected to give rise to a universal gravitational wave (GW) background, at frequencies smaller tha…
Universal Gravitational Wave Signatures of Cosmological Solitons
Kaloian D. Lozanov, Misao Sasaki, Volodymyr Takhistov
Cosmological solitonic objects such as monopoles, cosmic strings, domain walls, oscillons and Q-balls often appear in theories of the early Universe. We demonstrate that such scena…
Dark photon dark matter from an oscillating dilaton
Peter Adshead, Kaloian D. Lozanov, Zachary J. Weiner
We present a mechanism for generating ultralight dark photon dark matter in the early Universe via a dilatonlike scalar field coupled to the dark photon's kinetic term. Energy is i…
Production and backreaction of massive fermions during axion inflation with non-Abelian gauge fields
Peter Adshead, Aike Liu, Kaloian D. Lozanov
We study the production and backreaction of massive vector-like fermions in the background of a classical SU(2) gauge field during axion-driven inflation. We demonstrate all ultrav…
Lattice Simulations of Axion-U(1) Inflation
Angelo Caravano, Eiichiro Komatsu, Kaloian D. Lozanov +1
We present the first nonlinear lattice simulation of an axion field coupled to a U(1) gauge field during inflation. We use it to fully characterize the statistics of the primordial…
Enhanced Gravitational Waves from Inflaton Oscillons
Kaloian D. Lozanov, Volodymyr Takhistov
In broad classes of inflationary models the period of accelerated expansion is followed by fragmentation of the inflaton scalar field into localized, long-lived and massive oscillo…
The Physics of Light Relics
Cora Dvorkin, Joel Meyers, Peter Adshead +19
Many well-motivated extensions of the Standard Model predict the existence of new light species that may have been produced in the early universe. Prominent examples include axions…
Axion anomalies
Peter Adshead, Kaloian D. Lozanov
We study fermions derivatively coupled to axion-like or pseudoscalar fields, and show that the axial vector current of the fermions is not conserved in the limit where the fermion…
Lattice simulations of Abelian gauge fields coupled to axions during Inflation
Angelo Caravano, Eiichiro Komatsu, Kaloian D. Lozanov +1
We use a lattice simulation to study a model of axion inflation where the inflaton is coupled to a U(1) gauge field through Chern-Simons interaction. These kinds of models have alr…
Non-Gaussianity and the induced gravitational wave background
Peter Adshead, Kaloian D. Lozanov, Zachary J. Weiner
Scalar metric fluctuations generically source a spectrum of gravitational waves at second order in perturbation theory, poising gravitational wave experiments as potentially powerf…
Lattice Simulations of Inflation
Angelo Caravano, Eiichiro Komatsu, Kaloian D. Lozanov +1
The scalar field theory of cosmological inflation constitutes nowadays one of the preferred scenarios for the physics of the early universe. In this paper we aim at studying the in…
Spillway Preheating
JiJi Fan, Kaloian D. Lozanov, Qianshu Lu
In traditional models only an order one fraction of energy is transferred from the inflaton to radiation through nonperturbative resonance production in preheating immediately afte…
Self-gravitating Vector Dark Matter
Peter Adshead, Kaloian D. Lozanov
We derive the non-relativistic limit of a massive vector field. We show that the Cartesian spatial components of the vector behave as three identical, non-interacting scalar fields…
The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe
Rouzbeh Allahverdi, Mustafa A. Amin, Asher Berlin +23
It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. W…
Classical Decay Rates of Oscillons
Hong-Yi Zhang, Mustafa A. Amin, Edmund J. Copeland +2
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 thei…
Effects of Gravitational Chern-Simons during Axion-SU(2) Inflation
Leila Mirzagholi, Eiichiro Komatsu, Kaloian D. Lozanov +1
In this paper, we examine the viability of inflation models with a spectator axion field coupled to both gravitational and SU(2) gauge fields via Chern-Simons couplings. Requiring…
Compensated Isocurvature Perturbations in the Galaxy Power Spectrum
Alexandre Barreira, Giovanni Cabass, Kaloian D. Lozanov +1
We investigate the potential of the galaxy power spectrum to constrain compensated isocurvature perturbations (CIPs), primordial fluctuations in the baryon density that are compens…
GFiRe: a Gauge Field integrator for Reheating
Kaloian D. Lozanov, Mustafa A. Amin
We present a new numerical algorithm and code, , for solving the non-linear evolution of Abelian gauge fields coupled to complex scalar fields in homogeneous and isotr…
Lectures on Reheating after Inflation
Kaloian D. Lozanov
This lecture note provides a generic introduction to reheating after inflation, covering theoretical, phenomenological and observational aspects of the process.