Conveners
Early Universe
- Sachiko Kuroyanagi (IFT UAM-CSIC)
Early Universe
- Alexander Vikman (Czech Academy of Sciences (CZ))
Early Universe
- Jan Hamann (The University of New South Wales)
Early Universe
- Jinn-Ouk Gong
I introduce the novel phenomena of CP-violating inflation in a non-minimal Higgs framework where the inflaton has a complex non-minimal coupling to gravity leading to CP-violation - a necessary source of the baryon asymmetry. I discuss the inflationary dynamics of such a framework and its implications for baryogenesis.
The Type II Seesaw Mechanism provides a minimal framework to explain the neutrino masses involving the introduction of a single triplet Higgs to the Standard Model. We have demonstrated that this triplet Higgs alone can simultaneously generate the observed baryon asymmetry of the universe and the neutrino masses while playing a role in setting up Inflation. This is achievable with masses as...
The recent observation of ${}^4$He implies that our universe has a large lepton asymmetry. We consider the Affleck-Dine (AD) mechanism for lepton number generation. In the AD mechanism, non-topological solitons called L-balls are produced, and the generated lepton number is confined in them. We study the formation and evolution of the L-balls and find that the universe with large lepton...
The era of gravitational wave (GW) astronomy offers a new avenue to explore the early universe and with it an energy scale that may never be accessible to terrestrial colliders. This provides a fresh new way to investigate the phenomenology of grand unified theories (GUT). We construct an $SO(10)$ inspired Pati-Salam model encompassing an intermediate minimal left-right symmetric model. We...
My talk will mainly focus on an interesting reheating scenario where minimal gravitational interaction plays an important role that was ignored in the literature due to its supposedly weak strength. We take a systematic approach toward building a reheating scenario that can provide model-independent observable predictions. I shall start the discussion with the dark matter (DM) sector first,...
We propose a particle physics model that can alleviate the observed Hubble tension via an out-of-equilibrium hidden sector coupled to the visible sector. The particles that populate the dark sector consist of a dark fermion, which acts as dark matter, a dark photon, a massive scalar and a massless pseudo-scalar. Assuming no initial population of particles in the dark sector, feeble couplings...
Not a long ago, it was argued that the quantum gravity only tolerates de Sitter as a state on top of a valid vacuum. So, we construct the de Sitter state as a coherent state of gravitons on top of the Minkowski vacuum. To make the construction consistent, we use BRST quantization. As an example, first we study such construction in QED, and then we generalise it in linear gravity. Coupling the...
Based on: arXiv 2207.07142
Certain inflationary models like Natural inflation (NI) and Coleman-Weinberg inflation (CWI) are disfavoured by cosmological data in the standard ΛCDM+r model (where r is the scalar-to-tensor ratio), as these inflationary models predict the regions in the n_s−r parameter space that are excluded by the cosmological data at more than 2σ (here n_s is the scalar...
Features in the primordial power spectrum (PPS) can provide indications of the physics of the early Universe. We aim to analyse non-linear wave-mode coupling in models with global, logarithmic features through high-resolution dark-matter N-body simulations to calibrate a semi-analytic fitting function and apply Gaussian process regression to the results to obtain a continuous "map" of the...
Cosmologies with Light Massive Relics (LiMRs) as a subdominant component of the dark sector are well-motivated from a particle physics perspective, and can also have implications for the $\sigma_8$ tension between early and late time probes of clustering. The effects of LiMRs on the Cosmic Microwave Background (CMB) and structure formation on large (linear) scales have been investigated...
It is commonly assumed that the stochastic background of gravitational waves on cosmological scales follows an almost scale-independent power spectrum, as generically predicted by the inflationary paradigm. However, it is not inconceivable that the spectrum could have strongly scale-dependent features, generated, e.g., via transient dynamics of spectator axion-gauge fields during inflation....
CMB lensing is one of the most powerful techniques to describe the large-scale structures in the Universe. It extends our sight of structure evolution to very high redshift and can be used to constrain fundamental physical quantities, such as matter density and neutrino masses. Several competitive constraints have been achieved from the Planck CMB lensing power spectrum. However, the power...
Primordial non-Gaussanities can provide valuable information about the primordial universe. We explore the possibility of constraining them with photometric galaxy redshift surveys. Further, I will discuss how the inclusion of velocity maps via the kinetic Sunyaev Zeldovich effect can improve the estimator. Finally, I will comment on the prospects of reaching fnl<1 in the future.
In modern physics, with an increasing number of experiments, more available data will open a window towards testing new, increasingly complex-to-compute theories. Often, comparing this data against theory requires expensive computations arising from the sheer size of the dataset as well as numerical simulations required to go from theory to observables.
This in turn makes Bayesian inference...
As numerical complexities of cosmological models are increasing in recent years, so too are the demands for resources when computing solutions to the Einstein-Boltzmann equations with codes like \textsc{class} and \textsc{camb}. A solution to this demand is, of course, more computational power through increasingly better and faster hardware, but perhaps another and more sustainable approach is...
The kinematic SZ Sunyaev-Zel’dovich (kSZ) effect is produced by the peculiar motion of electrons in galaxy cluster when they scatter with cosmic microwave background (CMB) photons. As such, the kSZ effect carries information about the cosmic velocity field on large-scales and the gastrophysics of galaxy clusters, providing potentially powerful tests of gravity and structure formation....
As the largest gravitationally bound objects in the Universe, galaxy clusters are key tools to study large-scale structure formation processes and to constrain cosmological models. These studies, however, require the mass of clusters to be calibrated, for example with a mass-observable scaling relation. Systematic effects, in particular at high redshift, have an impact on this calibration and...
The microphysics of dark matter remains a mystery, with current data only setting upper bounds on interaction cross sections, or lower bounds on the mass in the case of a thermal relic. Going to higher redshift and smaller scales will let us improve these bounds, but more importantly, may allow us to distinguish between models with otherwise similar signals. In particular, I will present a...
Direct and indirect detection of decaying dark matter models often rely on an assumption of the generation of a standard model particle in the chain of decay channels. This however leads to some ambiguity on the origin of the standard model particles as there is an overlap with processes within baryonic physics. If, however, the decay is assumed to take place wholly within the dark sector...
A large number of studies, all using Bayesian parameter inference from Markov Chain Monte Carlo methods, have constrained the presence of a dark matter component decaying to invisible radiation. All such studies find a strong preference for either very long-lived or very short-lived dark matter.
In this talk, I will present our recent work, to appear on the arXiv in the coming weeks, in...
