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Théorie

Can Planck disprove anisotropic inflation?

Orateur: 
Jiro Soda
Home Institute: 
Kyoto University
Lieu: 
483A Malevitch
Horaire: 
Tuesday, 19. March 2013 - 14:00
 
In the conventional inflationary scenario, the statistical property of primordial fluctuations can be characterized by a statistically isotropic, Gaussian, and scale invariant power spectrum. However, in the presence of a vector field and its coupling to an inflaton, there could be vector hair during inflation which causes anisotropy in the expansion and the statistical property of primordial fluctuations. We named the model anisotropic inflation.

Naturally inflating on steep potentials through electromagnetic dissipation

Orateur: 
Lorenzo Sorbo
Home Institute: 
University of Massachusetts
Lieu: 
483A Malevitch
Horaire: 
Tuesday, 12. March 2013 - 14:00

 

Do structures affect the average and variance of the distance-redshift relation in the concordance model of cosmology?

Orateur: 
Fabien Nugier
Home Institute: 
LPTENS
Lieu: 
483A Malevitch
Horaire: 
Tuesday, 5. March 2013 - 14:00

I will try to give you an answer to that physically relevant question - and its implications on SNe Ia experiments - by taking advantage of the recent formulation of covariant averaging on the past light cone.

Modifications of gravity: what can we measure in principle?

Orateur: 
Ignacy Sawicki
Home Institute: 
University of Heidelberg
Lieu: 
483A Malevitch
Horaire: 
Tuesday, 26. February 2013 - 14:00

The difference between various models of dark energy or modifications of gravity becomes apparent at the level of growth of large-scale structure in the universe. In addition to measuring the background expansion, we are now beginning to probe this aspect.

Post-Newtonian approach to spin-orbit effects in inspiralling compact binaries

Orateur: 
Sylvain Marsat
Home Institute: 
IAP
Lieu: 
483A Malevitch
Horaire: 
Tuesday, 19. February 2013 - 14:00

The upcoming new generation of ground-based detectors such as LIGO and VIRGO is likely to allow for the first direct detections of gravitational waves, opening a new window on the universe and on extreme events in the regime of strong-field gravity.

Do gluons have a mass?

Orateur: 
Nicolas Wschebor
Home Institute: 
University of Montevideo
Lieu: 
483A Malevitch
Horaire: 
Tuesday, 12. February 2013 - 14:00

 

Galilean Genesis

Orateur: 
Paolo Creminelli
Home Institute: 
ICTP
Lieu: 
483A Malevitch
Horaire: 
Tuesday, 5. February 2013 - 14:00

I will describe possible alternatives to inflation, based on the spontaneous breaking of conformal invariance. I will study the possibility of violating the Null Energy Condition in these models and work out their predictions, which are severely constrained by the non-linear realization of the conformal group.

The Higgs boson mass and Standard Model up to the Planck scale

Orateur: 
Fedor Bezrukov
Home Institute: 
University of Connecticut
Lieu: 
483A Malevitch
Horaire: 
Tuesday, 29. January 2013 - 14:00

The Higgs boson with the mass announced by the LHC experiments corresponds within current precision to the boundary value between the situations when the electroweak vacuum is stable and metastable. I will discuss the developments in the calculation of this boundary mass and importance of measurement of other SM parameters (top quark mass and the strong coupling constant) at the lepton collider.

Second-order Boltzmann code and the CMB bispectrum from recombination

Orateur: 
Zhiqi Huang (CEA)
Orateur: 
Séminaire joint Groupes Théorie et Cosmologie
Lieu: 
366A-Klimt
Horaire: 
Tuesday, 22. January 2013 - 14:00

I will introduce CosmoLib2nd, a numerical Boltzmann code at second-order to compute CMB bispectra on the full sky. We compute the cosmic microwave background temperature bispectrum generated by nonlinearities at recombination on all scales. For cosmic-variance limited data to l_max = 2000, its signal-to-noise is S/N=0.47 and will bias a local signal by f_NL^{loc} ~ 0.82.

Light sterile neutrinos as dark radiation candidates

Orateur: 
Irene Tamborra
Lieu: 
FACe
Horaire: 
Tuesday, 15. January 2013 - 11:30
Recent  cosmological data favor additional relativistic degrees of freedom beyond  the three active neutrinos and photons. Light sterile neutrinos are prime candidates for such additional radiation. However, constraints on sterile neutrinos based on the current cosmological data have been derived assuming their thermalization at the Big Bang Nucleosynthesis (BBN) epoch.
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