Résumé / Abstract Journal-club_Postdoc

Journal-club Postdoc

« Constraining fundamental physics with Cosmology »

Eleonora Di Valentino
postdoc -

In this talk I will briefly show how current cosmological data can be used to constrain some aspects of fundamental physics presenting, as an example, the results from two recent projects in which I have been involved.
It is well known that axion particles, which solve in an elegant way the CP problem in QCD, can be produced in the primordial Universe both thermally, contributing to the hot dark matter of the Universe, or not thermally, contributing to the cold dark matter. In the first part of the talk, I will focus on the recent constraints from cosmology on the thermal axion mass, in the standard cosmological scenario LCDM as well as his extensions, but also taking into account the possibility that the primordial power spectrum could assume a more general shape than the usual power low description.
In the second part of the talk, I will show how the accuracy reached by current cosmological data allow us to give independent information on nuclear rates. Big Bang Nucleosynthesis (BBN) relates key cosmological parameters to the primordial abundance of light elements. Assuming the standard cosmological model, a combined analysis of Planck data and of recent deuterium abundance measurements in metal-poor damped Lyman-alpha systems provides independent information on the cross section of the radiative capture reaction d(p,\gamma)^3He converting deuterium into helium. Interestingly, the result is higher than the values suggested by a fit of present experimental data in the BBN energy range (10 - 300 keV), whereas it is in better agreement with ab initio theoretical calculations, based on models for the nuclear electromagnetic current derived from realistic interactions.
mardi 23 juin 2015 - 11:00
Salle des séminaires Évry Schatzman, Institut d'Astrophysique
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