Spring workshop on gravity and cosmology

Session

session III

27 May 2020, 10:00

Jagiellonian University

29. Looking for a healthy nonsingular bounce

Prof. Yifu Cai (University of Science and Technology of China)

27/05/2020, 10:00

In this talk I plan to review the cosmological paradigm of nonsingular bounces, which is often regarded as an alternative to inflation in describing the very early universe. Such a scenario, while can avoid the big bang spacetime singularity, often suffers from conceptual challenges, namely, the dangerous growth of anisotropic stress, the possibly existence of ghosts, gradient instabilities or...

30. Stable Cosmology in Generalised Massive Gravity

Michael Kenna-Allis

27/05/2020, 10:50

31. Gravitational footprints of massive neutrinos and lepton number breaking

Antonino Marciano

27/05/2020, 11:45

We investigate the production of primordial Gravitational Waves (GWs)
arising from First Order Phase Transitions (FOPTs) associated to
neutrino mass generation in the context of type-I seesaw schemes. We
examine both “high-scale” as well as “low-scale” variants, with either
explicit or spontaneously broken lepton number symmetry. In the latter
case, a pseudo-Goldstone boson, dubbed...

32. Cosmology with unparticles: Bounces, inflation, cyclic Universe and dark energy

Michal Artymowski

27/05/2020, 12:35

Our understanding of the Universe is based on general relativity and on the standard model of fundamental interactions. This picture suffers from several issues that cannot be explained by GR or SM, like primordial singularity, inflation, dark energy or dark matter. I will show how unparticles may solve at least some these problems and generate realistic cyclic Universe and dark energy

33. Some aspects of stochastic background of gravitational waves

Dr Shi Pi (IPMU, Tokyo University)

27/05/2020, 14:00

Our universe is fulfilled by stochastic background of gravitational waves with a large range of frequencies, which may have various astrophysical/cosmological origins in the early universe. As our universe is transparent to gravitational wave, it is a fossil recording the information of its generation and how our universe evolves. In this talk I will briefly review the stochastic background of...

34. Induced gravitational waves in general cosmologies

Dr Guillem Domenech (Heidelberg university)

27/05/2020, 14:50

Gravitational waves (GWs) are unavoidably induced at second order in cosmological perturbation theory. The so-called induced GWs are a crucial counterpart of the primordial black hole scenario and might be observable by future space based gravitational waves detectors. However, only the generation during radiation and matter domination eras has been analytically studied. In this talk, I will...

23. Big Bounce and inflation from spin and torsion

Nikodem Poplawski

27/05/2020, 15:45

The conservation law for the total (orbital plus spin) angular momentum of a Dirac particle in the presence of gravity requires that spacetime is not only curved, but also has a nonzero torsion.
The coupling between the spin and torsion in the Einstein-Cartan theory of gravity generates gravitational repulsion at extremely high densities, which should prevent a singularity in a black hole and...

36. Proof of the quantum null energy condition for free fermionic field theories

Taha Malik

27/05/2020, 16:35