A5059848615- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Galaxies: Formation, Evolution, Phenomena
- Dark Matter and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- History and Developments in Astronomy
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- Noncommutative and Quantum Gravity Theories
- Advanced Mathematical Theories and Applications
- Stochastic processes and financial applications
- Autonomous Vehicle Technology and Safety
- Relativity and Gravitational Theory
- Atmospheric chemistry and aerosols
- Stellar, planetary, and galactic studies
- Computational Physics and Python Applications
- Atmospheric and Environmental Gas Dynamics
- Astronomy and Astrophysical Research
- Superconducting and THz Device Technology
- IoT and GPS-based Vehicle Safety Systems
- Historical Economic and Social Studies
- Advanced Battery Technologies Research
Karlsruhe Institute of Technology
2018-2025
Institut für Informationsverarbeitung
2023-2025
University of Amsterdam
2015-2024
National Taiwan University
2020-2024
National Center for Theoretical Sciences
2022-2024
Institute of Astronomy and Astrophysics, Academia Sinica
2024
University Hospital of Zurich
2005-2023
University of Zurich
2023
National Center for Theoretical Sciences, Physics Division
2022
Vrije Universiteit Amsterdam
2022
We derive the complete spectrum of gravitational waves induced by primordial scalar perturbations ranging over all observable wavelengths. This scalar-induced contribution can be computed directly from observed and general relativity is, in this sense, independent cosmological model for generating perturbations. The is scale invariant on small scales, but has an interesting dependence large intermediate where do not redshift are hence enhanced relative to background density Universe. tensor...
The past two decades have seen transformative advances in cosmology and string theory. Observations of the cosmic microwave background revealed strong evidence for inflationary expansion very early universe, while new insights about compactifications theory led to a deeper understanding inflation framework that unifies quantum mechanics general relativity. Written by leading researchers field, this complete accessible volume provides modern treatment its connections elementary particle After...
The universe is smooth on large scales but very inhomogeneous small scales. Why the spacetime modeled to a good approximation by Friedmann equations? Are we sure that small-scale non-linearities do not induce backreaction? Related this, what effective theory describes scales? In this paper make progress in addressing these questions. We show for long-wavelength behaves as viscous fluid coupled gravity: integrating out short-wavelength perturbations renormalizes homogeneous background and...
Scattering amplitudes at weak coupling are highly constrained by Lorentz invariance, locality and unitarity, depend on model details only through constants the particle content of theory. For example, four-particle analytic for contact interactions have simple poles with appropriately positive residues tree-level exchange. In this paper, we develop an understanding inflationary correlators which parallels that flat-space scattering amplitudes. Specifically, study slow-roll inflation...
Supersymmetry plays a fundamental role in the radiative stability of many inflationary models. Spontaneous breaking symmetry inevitably leads to fields with masses order Hubble scale during inflation. When these couple inflaton, they produce unique signature squeezed limit three-point function primordial curvature perturbations. In this paper, we make connection between naturalness, supersymmetry, Hubble-mass degrees freedom, and precise. To study physics model-insensitive way, develop...
We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes physics inflation. focus on prospects for using CMB to differentiate various inflationary mechanisms. In particular, a detection primordial B‐mode would demonstrate that inflation occurred at very high energy scale, and inflaton traversed super‐Planckian distance in field space. explain how such or constraint illuminate aspects Planck scale. Moreover, can constrain scale‐dependence...
Abstract. A reliable and precise in situ CO2 CO analysis system has been developed deployed at eight sites the NOAA Earth System Research Laboratory's (ESRL) Global Greenhouse Gas Reference Network. The network uses very tall (> 300 m) television radio transmitter towers that provide a convenient platform for mid-boundary-layer trace-gas sampling. Each analyzer three sample inlets profile sampling, complete vertical is obtained every 15 min. instrument suite one site augmented with cavity...
We study the imprints of massive particles with spin on cosmological correlators. Using framework effective field theory inflation, we classify couplings these to Goldstone boson broken time translations and graviton. show that it is possible generate observable non-Gaussianity within regime validity theory, as long masses are close Hubble scale their interactions break approximate conformal symmetry inflationary background. derive explicit shape functions for scalar tensor bispectra can...
We study the gravitational-wave (GW) signatures of clouds ultralight bosons around black holes (BHs) in binary inspirals. These clouds, which are formed via superradiance instabilities for rapidly rotating BHs, produce distinct effects population BH masses and spins, a continuous monochromatic GW signal. show that presence companion greatly enriches dynamical evolution system, most remarkably through existence resonant transitions between growing decaying modes cloud (analogous to Rabi...
A bstract key insight of the bootstrap approach to cosmological correlations is fact that all correlators slow-roll inflation can be reduced a unique building block — four-point function conformally coupled scalars, arising from exchange massive scalar. Correlators corresponding particles with spin are then obtained by applying spin-raising operator scalar-exchange solution. Similarly, massless external fields derived acting suitable weight-raising operator. In this paper, we present...
We extend the cosmological bootstrap to correlators involving massless particles with spin. In de Sitter space, these are constrained both by symmetries and locality. particular, isometries become conformal on future boundary of spacetime, which reflected in a set Ward identities that must satisfy. solve acting weight-shifting operators scalar seed solutions. Using this approach, we derive three- four-point spin-1 spin-2 fields conformally coupled scalars. Four-point functions arising from...
A bstract Much of the structure cosmological correlators is controlled by their singularities, which in turn are fixed terms flat-space scattering amplitudes. An important challenge to interpolate between singular limits determine full at arbitrary kinematics. This particularly relevant because singularities not directly observable, but can only be accessed analytic continuation. In this paper, we study rational — including those gauge fields, gravitons, and inflaton whose tree level poles...
Superradiant instabilities may create clouds of ultralight bosons around rotating black holes, forming so-called "gravitational atoms". It was recently shown that the presence a binary companion can induce resonant transitions between bound states these clouds, whose backreaction on binary's orbit leads to characteristic signatures in emitted gravitational waves. In this work, we show interaction with also trigger from unbound cloud—a process refer as "ionization" analogy photoelectric...
This white paper summarizes recent progress in the cosmologicalbootstrap, an approach to study of statistics primordialfluctuations from consistency with unitarity, locality and symmetryassumptions. We review key ideas bootstrap method, aneye towards future directions ambitions program. Focusing onrecent involving de Sitter quasi-de backgrounds, wehighlight role singularities unitarity constraining theform correlators. also discuss nonperturbative formulations ofthe bootstrap, connections...
We derive a microscopic bound on the maximal field variation of inflaton during warped D-brane inflation. By result Lyth, this implies an upper limit amount gravitational waves produced show that detection at level $r>0.01$ would falsify slow roll In DBI (Dirac-Born-Infeld) inflation, detectable tensors may be possible in special compactifications, provided $r$ decreases rapidly also for case inflation with quadratic potential, current observational constraints imply strong bounds five-form flux.
We present a detailed analysis of an explicit model warped D-brane inflation, incorporating the effects moduli stabilization. consider potential for D3-brane motion in conifold background that includes fluxes and holomorphically-embedded D7-branes involved Although significantly modify inflaton potential, they do not correct quadratic term hence cause uniform change slow-roll parameter eta. Nevertheless, we simple example based on Kuperstein embedding D7-branes, z_1=constant, which can be...
Soft limits of inflationary correlation functions are both observationally relevant and theoretically robust. Various theorems can be proven about them that insensitive to detailed model-building assumptions. In this paper, we re-derive several these in a universal way. Our method makes manifest why soft such an interesting probe the spectrum additional light fields during inflation. We illustrate abstract results with case study quasi-single-field
We investigate whether explicit models of warped D-brane inflation are possible in string compactifications. To this end, we study the potential for D3-brane motion a conifold that includes holomorphically embedded D7-branes involved moduli stabilization. The presence significantly modifies inflaton potential. construct an example based on very simple and symmetric embedding due to Kuperstein, z1= const, which it is fine-tune so slow-roll can occur. resulting model rather delicate: occurs...
Fluctuations in the cosmic neutrino background are known to produce a phase shift acoustic peaks of microwave background. It is through sensitivity this effect that recent CMB data has provided robust detection free-streaming neutrinos. In paper, we revisit anisotropy spectrum as probe new physics. The particularly interesting because its physical origin strongly constrained by analytic properties Green's function gravitational potential. For adiabatic fluctuations, requires modes propagate...