-
Dr Lorenzo Bordin (University of Nottingham)21/01/2019, 09:00physics of primordial universe
The existence of light particles with spin during inflation is prohibited by the Higuchi bound. This conclusion can be evaded if one considers states with a sizeable coupling with the inflaton foliation, since this breaks the de Sitter isometries. The action for these states can be constructed within the Effective Field Theory of Inflation, or using a CCWZ procedure. Light particles with spin...
Go to contribution page -
Dr Takeshi Kobayashi (ICTP, Trieste )21/01/2019, 09:45physics of primordial universe
For more than twenty years, it has been argued that the Weyl anomaly of quantum electrodynamics sources cosmological magnetic fields in the early universe. If true, this would be a natural way to produce the seed magnetic fields of our universe within the Standard Model. In this talk, I will examine this long-standing claim and show that there is actually no production of coherent magnetic...
Go to contribution page -
Dr Ryo Namba21/01/2019, 11:00
Detection of tensor mode fluctuations at the largest cosmological scales is often expected to provide a robust evidence of inflation and to fix the inflationary energy scale. Such direct connection is however applicable only when gravitational waves (GWs), the source of tensor perturbations, are effectively decoupled from other energy contents. However, spin-1 particles can be produced...
Go to contribution page -
Mr Przemysław Małkiewicz (National Centre for Nuclear Research)21/01/2019, 11:45
I will talk about the Dirac procedure for constrained systems applied to the Arnowitt-Deser-Misner formalism linearized around the Friedmann-Lemaitre universe. I will employ some basic concepts such as Dirac observables, Dirac brackets, gauge-fixing conditions, reduced phase space, physical Hamiltonian and physical dynamics, and the canonical isomorphism between different gauge-fixed surfaces....
Go to contribution page -
Dr Tomohiro Fujita (Geneva Uni./Kyoto Uni.)21/01/2019, 14:00
Identification of dark matter has been an outstanding problem in
Go to contribution page
physics for decades, and axion (or axion like partciles) is its
candidate with great motivations. A number of observations and experiments have tried to detect axion by using the axion-photon conversion by assuming the axion is coupled to photon, while no signal yet to be found. In this talk, I will discuss new techniques to... -
Dr Wei Xue (CERN)21/01/2019, 14:45
In this talk, I will introduce a novel model to explain the small structure observations of galaxies. This model contains ultralight bosonic fields and heavy fermionic particles as dark matter. The second part of talk will revisit the idea of femtolensing of gamma ray bursts, which has been put forward as an exciting possibility to probe exotic astrophysical objects with masses below 10^−13...
Go to contribution page -
Dr Zhong-Zhi Xianyu (Harvard University)21/01/2019, 16:00
Abstract: Gravitational wave (GW) astronomy provides us a unique chance to probe invisible matter in the universe. In this talk we introduce several ways of probing dark ambient matter of compact binaries through GWs. We first present some analytical understanding of the distribution of binaries' orbital parameters and its relation to binaries' formation channels. Then, we describe how the...
Go to contribution page -
Dr Dražen Glavan (louvain-la-neuve university)21/01/2019, 16:45
The rapid expansion of inflationary universe amplifies microscopic linear quantum fluctuations of non-conformally coupled fields such as the minimally coupled massless scalar, and generates large superhorizon correlators. On the other hand, conformally coupled fields such as the photon are insensitive to the expansion itself. However, if the photon couples to the complex scalar the effect of...
Go to contribution page -
Prof. Atsushi Naruko (Tohoku University)22/01/2019, 09:00gravity theories
In this talk, we construct Lorentz-invariant massive spin-2
Go to contribution page
theories in a flat space-time. Starting from the most general action of a massive spin-2 field whose Lagrangian contains up to quadratic in first derivatives of a field, we investigate new possibilities by using the Hamiltonian analysis. By imposing degeneracy of the kinetic matrix and the existence of subsequent constraints, we... -
Prof. Chunshan Lin (University of Warsaw)22/01/2019, 09:45gravity theories
Probably not. I will introduce some different gravity theories which are as good as GR in the sense that all of constraints are first class and therefore a graviton has only 2 polarisations and the structure of the theory at low energies is thus expected to be stable against quantum corrections.
Go to contribution page -
Prof. Alexander Vikman (CEICO, Prague)22/01/2019, 11:00
In arXiv:1811.09547 we introduced an interesting new Weyl-invariant and generally-covariant vector-tensor theory with higher derivatives. This theory can be induced by extending the mimetic construction to vector fields of conformal weight four. We demonstrated that in gauge-invariant variables this novel theory reduces to the Henneaux–Teitelboim description of the unimodular gravity. Hence,...
Go to contribution page -
Prof. Dumitru Ghilencea (IFIN Bucharest)22/01/2019, 11:45
We investigate the spontaneous breaking of Weyl conformal geometry to Einstein gravity in the presence/absence of matter with non-minimal couplings and possible applications to model building beyond SM.
Go to contribution page -
Prof. Alexey Golovnev (St. Petersburg State University)22/01/2019, 14:00
The modern theory of ghost-free massive gravity hinges upon the notion of a square root of a matrix. This is non-trivial and not unique. It makes the standard perturbation theory in terms of matrices problematic, and in some cases even impossible. I will describe the mathematics behind these issues, and also discuss a method of dealing with perturbation theory around a given solution in terms...
Go to contribution page -
Dr Marek Lewicki (Kings College)22/01/2019, 14:45
What is the maximum possible strength of a first-order electroweak phase transition and the resulting gravitational wave signal? While naively one might expect that supercooling could increase the strength of the transition to very high values, for strong supercooling the Universe is no longer radiation-dominated and the vacuum energy of the unstable minimum of the potential dominates the...
Go to contribution page -
Dong-han Yeom (APCTP, Pohang)22/01/2019, 16:00
The information loss problem in black hole physics is a very important but unresolved problem. I will review the issue including the recent discussion with the firewall controversy. Instead of the firewall conjecture or other candidates of resolutions, I will suggest that the Euclidean path integral sheds some lights to the problem.
Go to contribution page -
Prof. Ignacy Sawicki (Institute of Physics, Czech Academy of Sciences)22/01/2019, 16:45
I will review the problem of the acceleration of the expansion of the universe at late times and discuss how models of modifications of gravity can provide an alternative mechanism to the cosmological constant. I will discuss the space of models, how to best think about the generic effects these models have on structure formation and therefore how they can be constrained through observations....
Go to contribution page
Choose timezone
Your profile timezone: