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Invisible's Journal Club

Past events

  • Date of the event: Tue, 13/05/2014 - 15:00

    Speaker: Daniel G. Figueroa

    Affiliation: Geneva U. 

    Abstract: We will discuss the basics of the Inflationary paradigm, reviewing the original motivations, the general predictions of the simplest scenarios, and latest BICEP2 results suggesting a potential discovery of the long-seeked inflationary tensor modes. This lecture aims to explain the basic aspects of Inflation to theoretitcal physicisists in general, without assuming any prior knowledge on inflation.



  • Date of the event: Tue, 29/04/2014 - 15:00

    Title: The Unexpected Detection of a 3.56 keV Emission Line: Sterile Neutrino Decay Signature?tle:  

    Presenter: Randall Smith (Harvard Smithsonian Center for Astrophysics)

    Abstract: Bulbul et al. (arXiv:1402.2301) detected a weak unidentified emission line at ~3.56 keV in the stacked XMM spectra of 73 galaxy clusters spanning a redshift range 0.01 − 0.35. The line is seen at > 3σ statistical significance in all three independent spectral selections of one XMM detector (MOS) and the full sample of the second (noisier) PN spectra. The line is also detected at the same energy and consistent flux in the Chandra ACIS-S and ACIS-I spectra of the Perseus cluster, although it is not seen in the ACIS-I spectrum of Virgo.  Although there are many known X-ray emission lines in the 2-10 keV bandpass, I will discuss why there should be no atomic transitions in thermal plasma at this energy, leaving the intriguing possibility that this line is from the decay of sterile neutrinos.

  • Date of the event: Tue, 01/04/2014 - 15:00

    Title: Inflation after Planck and BICEP2

    Presenter: Jan Hamann (CERN)

    Abstract: Since its introduction more than 30 years ago, the idea of cosmic inflation has been remarkably successful. Inflation not only solves a number of fine-tuningproblems, but is also the most convincing candidate for the generating the seeds of cosmic structure. I will briefly recap the generic predictions of the inflationary mechanism, review how they can be tested observationally, and confront them with Cosmic Microwave Background (CMB) precision data from the Planck experiment. Finally, Iwill present the recent measurement of the CMB B-polarisation spectrum by the BICEP2collaboration and discuss its implications for cosmology.


  • Date of the event: Tue, 18/03/2014 - 15:00

    Title: Composite models of self-interacting dark matter

    Presenter: Jim Cline

    Abstract: There are interesting hints that standard cold dark matter does not correctly predict the small scale structure of the universe, while dark matter with strong self-interactions may do so.  Models in which the dark matter is composite--dark analogs of atoms, mesons, nucleons, glueballs--can naturally have large self-interactions.  I will briefly review the experimental hints for dark matter self-interactions, and discuss implications of these models for direct detection, the CMB, nucleosynthesis, and the LHC.

  • Date of the event: Tue, 11/02/2014 (All day)

    Title: On the origin of the PeV neutrinos
    Presenter: Esteban Roulet (Bariloche)
    Abstract: I will discuss the contribution to the PeV neutrino fluxes produced by the interactions of extragalactic cosmic rays during their propagation through the radiation backgrounds in the Universe and consider the implications for the neutrinos recently observed by IceCube.

  • Date of the event: Tue, 28/01/2014 - 15:00

    Title: Testing General Relativity with Cosmology

    Presenter:  Pedro Ferreira (Oxford U)

    Chair: Carlos Peña-Garay

    Abstract: With the successes of observational cosmology, a new window has opened up on to gravitational physics.

  • Date of the event: Tue, 10/12/2013 (All day)

    Title: Correlation between DM production and baryogenesis

    Presenter:  Giorgio Arcadi (Goettingen U)

    Abstract: The explanation of the ratio of the Baryon and Dark Matter abundances is one of the most intriguing cosmological puzzles. A recently proposed interesting possibility is to correlate both DM production and the generation of baryon asymmetry to the WIMP paradigm. In the first part of the talk I will review the basic mechanism and discuss some realizations. 



  • Date of the event: Tue, 26/11/2013 - 17:00

    Title: Issues in mass hierarchy discrimination via reactor neutrino oscillations

    Presenter:  Eligio Lisi (INFN Bari)

    Abstract: We revisit some issues related to the precision calculation and the statistical analysis of reactor neutrino spectra, in the context of medium baseline experiments aiming at discriminating the neutrino mass hierarchy. Concerning precision calculations, we cast the oscillation probability in an analytical form which makes manifest hierarchy, damping and matter effects; we also include recoil effects through analytic modifications of the energy resolution function.