The distance ladder relying on supernovae yields higher values of the Hubble constant H0 than those inferred from the inverse distance ladder, calibrated on early-time physics and relying on observations typically involving cosmic microwave background (CMB) in combination with galaxy surveys. Such discrepancy has come to be known as the ‘Hubble tension’. This has motivated the exploration...
The observation of gravitational waves by the LIGO/Virgo collaborations and the promise of future experiments underscores the need for increasingly more precise theoretical predictions. It has recently been demonstrated that scattering-amplitude techniques, originally developed for QCD calculations, can push the state of the art and provide results that are difficult to obtain by more standard...
Advanced LIGO and advanced Virgo conducted their third science run O3 between April 2019 and March 2020. So far, the observations of the first six months of O3 have been reported and published with the catalog GWTC-2.
We will provide an overview of the contents of GWTC-2, which includes 39 candidate gravitational wave events associated with compact binary mergers.
These observations give new...
The LIGO-VIRGO data presents a magnificent opportunity for exploring the uncharted territory of binary compact objects.
We have developed an independent analysis pipeline for analyzing the public LIGO-VIRGO data from the first two observing runs. We have developed several novel techniques, and revisited all the choices essential for such an analysis. The resulting improvement (comparing to...
The LiteBIRD satellite is a CMB mission targeting the B-mode polarization and the primordial gravitational waves signal that it is expected to carry. Scheduled for flight in the late 2020s, LiteBIRD will complement ground-based efforts by mapping angular scales and observational frequencies unreachable from the ground. In particular, LiteBIRD will constrain both the reionization and the...
An inflation-probing B-mode signal in the polarization of the cosmic microwave background (CMB) would be a discovery of utmost importance in physics. While recent BICEP results hinting upon the detection of such a signal rallied enthusiasm, Planck showed that this breakthrough is still out of reach, because of contamination from Galactic dust. To get to the primordial B-modes, we need to...
Modern cosmology profoundly involves particle theory beyond the Standard Model to explain long-standing puzzles: the origin of the observed matter asymmetry, nature of dark matter, massive neutrinos, and cosmic inflation. In this talk, I will explain that a new setup based on embedding axion-inflation in the gauge extensions of the SM can possibly solve and relate these seemingly unrelated...
We study the large-scale anisotropy of the Universe by measuring the dipole in the angular distribution of a flux-limited, all-sky sample of 1.36 million quasars observed by the Wide-field Infrared Survey Explorer (WISE). This sample is derived from the new CatWISE2020 catalog, which contains deep photometric measurements at 3.4 and 4.6 μm from the cryogenic, post-cryogenic, and reactivation...
Type Ia Supernovae (SNe Ia) are critical tools for measuring the current expansion rate of the universe, described by the Hubble Constant, and the accelerating expansion, due to a mysterious `dark energy’. As measurements from SNe Ia continue to be important and exciting, there has been widespread interest on strengths and limitations of using SNe Ia in analyses. Here, I review the latest...
I shall review the status of dS vacua in string theory in a (hopefully) pedagogical manner. Most of the talk will be about general principles and constraints. But in order to highlight the intricacies of dS model building I will address some details of the particular KKLT scenario.
Constructing cosmological solutions in the context of string theory has been notoriously elusive. In this talk I will discuss, from a bottom up point of view, possible ways of obtaining de Sitter/cosmological geometries based on the gauge/gravity duality. These methods are alternative to the standard route (finding a semiclassical vacuum solution of string theory with an effective...
The detection of a Fast radio burst (FRB) in 2007 was a major unexpected discovery in astronomy in decades. Hunting for FRBs and measuring their physical properties have become one of the leading scientific goals in astronomy. It is well established that many FRBs are located at a distance of several billion lightyears, and therefore they are the brightest known transients in the universe in...
Sub-percent precision measurements of the kSZ effect -- small-scale anisotropies in the CMB due to scattering off clouds of moving ionized gas -- will be possible with upcoming CMB and galaxy surveys, so it is timely to ask what science can be extracted with such measurements. I will discuss how recasting kSZ tomography as a bispectrum measurement allows for a unified framework under which...
Cosmological observations give us the unique opportunity to probe the fundamental laws of physics at very high energies as well as the perturbative regime of quantum gravity. Unfortunately, due to the creativity of theorists and the paucity of data about the primordial universe, there is a huge number of models compatible with all measurements, featuring a wide variety of mechanisms,...
I will review the status of the no-boundary proposal, with a particular emphasis on definitions in minisuperspace. This setting allows one to shed light on how to define boundary conditions when the manifolds under consideration are not supposed to have a boundary. A similar situation is encountered for the canonical partition function in asymptotically AdS spaces, and the relation between the...
Neutrino capture on beta-decaying nuclei is currently the only known potentially viable method of detection of cosmic background neutrinos. It is based on the idea of separation of the spectra of electrons or positrons produced in captures of relic neutrinos on unstable nuclei from those from the usual β-decay and requires very high energy resolution of the detector, comparable to the neutrino...
If the mass of the Higgs boson is put to zero, the classical Lagrangian of the Standard Model (SM) becomes conformally invariant (CI). Taking into account quantum non-perturbative QCD effects leads to electroweak symmetry breaking with the scale ~100 MeV which is three orders of magnitude less than it is observed experimentally. Depending on the mass of the top quark, the radiative corrections...
