Magic Monday Journal Club

17th November 2014

Back to the  main page


A small room (the Cosmology one) but overfull packed!!! Wa a real great pleasure to see all of you there, from Polytechnique to Jussieu guys.. Always a real pleasure to have great discussions and exchanges. We really appreciate it a lot, and this was maybe one of the best MMJC we had. We discussed:

WIMPs at the Galactic Center

by P. Agrawal, B. Batell, P.J. Fox and R. Harnika

P. Fox et al, had a more detailed look on this Galactic Center excess (call it Hooperon, Gooperon, Wenigon, Morsellon, or Foxon). The authors showed that if the final product of the annihilation is almost at rest (production near threshold) then the shape of the spectrum should also exhibit similar features that the too-much claimed 30 GeV DM annihilating into bbar. hh or tt final states can also explain such an excess. No need to read all the paper, you can just directly have a look at their Fig. 2 and their Eq. (2.6) to understand their point.  The results are perfectly summarized in Fig.4 which can even be taken for your future analyses. The rest is some model application to that (Higgs portal and SUSY), but no one really care about it. The main results is in Fig.4, which open a lot of new possibilities to fit this GC excess (whatever is it). You can find an annotated version of the paper here, and THE FIRST indication of a signal from a FERMI presentation in 2009 (!!!) much before Hooper here.

Millisecond pulsars and the Galactic Center gamma-ray excess: the importance of luminosity function and secondary emission

by J. Petrovic, P. D. Serpico, G. Zaharijas

As always when it comes to papers by Pasquale or Gabrijela, very serious work on the possibility that FERMI missed a lot of millisecond pulsars from the region around the GC. The hypothesis of Hooper et al. was mainly based on a spectrum and distribution, extrapolated to the GC, from local data. clearly, looking at the Fig.1 of this paper, we see that FERMI could have missed maybe 80% of the millisecond pulsar surrounding the region were the GC excess is lying. In other words, nobody really knows about the behavior and population of these animal in this region, drawing any conclusion then is quite... «cavalier».  You can find an annotated version of the paper there.

Where do the 3.5 keV photons come from? A morphological study of the Galactic Center and of Perseus

by E. Carlson T. Jeltema S. Profumo

A different analysis for the 3.5 keV line, this time concentrating on the morphology of the signal. Nice one. The authors decided to look at Perseus and Galactic Center to see if the morphology of the signal can follows a spherical distribution, which could motivate in this case a dark matter interpretation of the excess.  Just look at the middle left plot of fig.2 to understand that, in the case of GC, the signal seems to follow a bubble shape which is much more similar to the one of the Argon (on its left). Concerning Perseus, the Figure 3 is less clear, but the authors affirm that it cannot be compatible with a spherical halo. If I would follow the Gordy Kane way of thinking I would say: «this is the proof that the DM does not follow symmetrical profiles». But I am far to be in the G. Kane mind, so I would say.... Puzzling... The annotated paper is here.

17_Anderson.pdA Search for Dark Matter Annihilation in Dwarf Spheroidal Galaxies with Pass 8 Data

by B. Anderson on behalf of FERMI collaboration

Yeap, just need to go to the slide 12 to understand that the new dwarf analysis is quite strong and begin to touch region of dark matters below 100 GeV!!! Still stay cautious as these are preliminary results, not yet published, but for sire, this analysis will be included in your next constraints...

State of new physics in b -> s transitions

by W.Altmannshofera and D. Straubb

This is an update on new physics explanation of anomalies in b-to-s transitions. The older  anomaly in differential distributions in  B → K* μ+ μ- was recently strengthened by a ~2.5 sigma flavor non-universality in B → K μ+ μ-/B → K e+ e- branching fractions. Adding higher dimensional 4-fermion operators beyond the standard model greatly improves the global fit to data. The only downside is that concrete new physics models fitting the data (for example, heavy Z') require very stretched parameters. 

Resolving the Tevatron top quark forward-backward asymmetry puzzle

by   M. Czakon, P. Fiedler, and A. Mitov

Finally, an NLO (QCD 2-loops) calculation of the forward-backward asymmetry of the top pair production in the SM  has been completed. Th NLO corrections can be important, especially for the differential distribution in pT of the ttbar pair.  The inclusive value goes up to 9.5% with an estimated error less than 1%. This is in decent agreement with the most recent experimental results from the Tevatron, so no new physics there folks. 

Observations of the Penetrating Radiation on Seven Balloon Flights

by Viktor F. Hess (1912)

This is the first time where Hess published his result concerning the increasing of radiation while going up to the air at more than 5000 meters!!! To understand the impact of such a discovery, one should keep in mind that at this epoch, radioactivity were believed to be originated from the earth, and so from the soil, and then one should observe an exponential decreasing of the radioactivity while going up. However, already in 1910,  Wulf went on top of the Eiffel tower. And while he should have observed only 10% of the soil radioactivity, he observed a very small decrease. In his different balloon flights, Hess measured the increase of radioactivity (first table) that he attributed to «a radiation of very high penetrating power [which] enters our atmosphere from above, and still produces in the lowest layers a part of the ionization observed in closed vessels». This was the discovery of the cosmic rays.