Magic Monday Journal Club

March the 24th  2014

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A nice dynamic MMJC. Special thanks to Roberto and the guy in moonboots and underwear in the south pole night...


by BICEP collaboration

A great thanks to Roberto who took the courage to read the paper and told us the pro and cons of the now-famous analysis. A lot have been said on the subject, and I am pretty sure any readers has his own point of view on the «discovery». Discussions on transplanckian mass, validity of Lyth limit, second peak (?) axionic DM exclusion and all that.  You will find an annotated version of the paper around this place. If you want to discuss with firends, you can also have a look at this bar or this restaurant, or any place around there. I think we can deserve a price to S. Richter from the collaboration for his courage.

The Effective Hooperon

by A. Alves, S. Profumo, F. S. Queiroz, W. Shepherd

The title does not ring so sexy to be honest, but a very nice work where the author (classical working group) concentrated on  the classical effective operator lists (D1, D2, ..,C1, C2..) trying to fit at the same time PLANCK, the FERMI gamma ray excess at the Galactic center around 3 GeV (what they called «Hooperon») and avoiding the LHC bounds. Some blabli blabla, but interesting result that you can understand easily  just putting your right eye on figs. 1 and 2 while keeping the left one on their table I. Nice discussions concerning velocity suppression, mass helicity flips for each operators. You can find an annotated version of the paper here.

Axial Dark Matter: the case for an invisible Z’

by Y. Mambrini and O. Lebedev

Ok, ok, ok... What to say when one of the Magicians is the author of the work presented here. Trying to be neutral (can I?) this proposition of axial dark matter, supposing a dominant axial coupling of the dark matter to a Z’ allows at the same time to fit naturally WMAP/PLANCK constraints without any tension from the direct detection (Spin Dependent), LHC or LEP searches. Natural and nice model that I urge you to read before sleeping to have the sweetest dream of 2014 for sure!!!. You can find an annotated version of the paper here.

Coy Dark Matter and the anomalous magnetic moment

by A. Hektor and L. Marzola

Hmmmm.. Not so easy to say anything really and fully positive on this work. Of course a lot of efforts have been made to complete the analysis, a lot of energy has been spent.. Trying to conciliate the 3 GeV FERMI excess and anomalous moment of the muon and not excess for the electron anomalous moment and FERMI dwarf limits is almost impossible. You need a «Coy Dark Matter» (it is just a classical fermion coupling to a pseudoscalar, nothing spectacular in this «coy» model, it is exactly what happens in the NMSSM with light pseudoscalar). I let you jump directly to their Fig.2 and find as a puzzle game what is left in the parameter space. Let say, almost nothing. You can find an annotated version of the work around here.

A quantum theory of the scattering of X-rays by light elements

by A.H. Compton


Do not be deceived by the title. It is not «only» the discovery of the Compton in this paper: the quantum version of the classical Thomson effect, diffraction of light on an electron. We are in 1922 (the paper was published 6 months after the results have been presented due to referee delay). Bohr succeeded to Einstein for the Nobel Prize of physics. They disagree strongly on the interpretation of the «quantum of light». Is it just a mathematical trick or should we consider this quantum as a particle, as a «photon». Compton, for the first time, proved in this paper that the quantum can scatters at large angle, with a reduced wavelength. The difference of energy between the original and scattered particle correspond to the kinetic energy given to the expulsed electron. Very very pedagogical article which open the way to wave-particle duality. Forget Cindirella, read it to your kids. Or your cat, depends your situation. You can find the annotated original paper here or in the historical section.