Magic Monday Journal Club

16th February 2015

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«Back from a cold Moscow, was so great to see all of you in a cold Paris»

Y.M. after a deep thought around his morning cofee.

The MMJC was great, with a lot of people around, especially a strong group from the PLANCK collaboration. Than k you all of you for your presence there. These are the papers we discussed this time:

Planck 2015. XX. Constraints on inflation

by PLANCK collaboration

Planck put out the final paper on inflation. The money plot shows the constraints on single-field inflation in the ns-r plane. Some models (for example φ^2 inflation) are comfortably excluded, other (for example R^2 inflation) remain consistent with all data.  

Evidence for dark matter in the inner Milky Way

by F. Iocco, M. Pato and G. Bertone

Mmmmmm.. To tell you the truth, I do not really know what to think about this work, published in Nature finally. Especially after a discussion with  . I was in Korea when I saw Fa    bio presenting this work last year. It is a serious work, where the authors compiled all the «rotation-like» data (supposing circular orbitals, which seems to be quite a strong hypothesis) to conclude that dark matter species should be present in the inner MW region (below let say 5 kpc).   Just look directly to their Fig.2 and you will understand everything. They compared their compiled data with «theoretical» model of Gaz, Bulge and disk. It seems that adding a dark component respecting NFW profiles ameliorate the fit. In view of the HUGE uncertainties of such a work, I do not know what to think about a «5 sigma» significance in this condition. You can find an annotated version of their paper there.

Dark Matter Annihilation in the Large Magellanic Cloud with the Fermi Large Area Telescope

by  M. R. Buckley, E. Charles, J. M. Gaskins, A. M. Brooks,  A. Drlica-Wagner, P. Martin, and G. Zhao

A bunch of person who decided to look at limits from dark matter interaction, not in our galaxy, not in the dwarf one, but in this «bastard» (Mum, pardon my sins) Large Magellanic Cloud. this galaxy is smaller than ours, at the same time bigger than the classic dwarf ones, and so excluded by the famous «dwarf spheroidal galaxy» survey. At the end, if you are in a hurry because your dog needs to go out, jump on the fig.22, it summarizes all the rest. Conclusion? Bha. Less good that the Galactic Center or the combined dwarf analysis, but good that the analysis has been done in any case. You can find an annotated version of their paper here.

Spectral analysis of the high-energy IceCube neutrinos

by   S. Palomares-Ruiz, A. C. Vincent and O. Mena

This analysis can be seen as complementary (or in competition with, depends your state of mind) to the «official» Icecube one 1502.03376. The authors showed that the predicted (1:1:1) ration for the flavored neutrino arriving on earth is quit compatible with the data of the > 100 TeV events measured by the IceCube. The authors gives also a very nice fit of the energy spectrum, on their Fig.6 and Eq.(70). Can be useful for any UHE neutrino studies. You can find an annotated version of their paper there.

Search for Long-Lived Particles in e+e−Collisions

by  BaBar collaboration

BaBar made a search for a long lived scalar S produced in B > X S decays, where S has a decay length between 1cm and 1m and decays to a pair of muons, electrons, kaons, etc. Their results exclude a small new portion of the parameter space of the model where a light singlet scalar mixes with the Higgs boson. 

Bringing the Galaxy’s dark halo to life

by   T. Piffl1, Z. Penoyre, J. Binney

Binney, one of the world specialist of simulations and dark matter halos gives us the spatial distribution of dark matter halo extracted from velocity distribution (Eqs.1 and 4) for different kind of theoretical velocity distribution, taking into account the effect of baryons in the galaxy. Really interesting work, perpendicular and complementary to the classical N-body simulations. Their Fig.4  summarizes quite well their work. You can find an annotated version of their paper here.

Dynamically Induced Planck Scale and Inflation

by K. Kannike, G. Hütsi, L. Pizza, A. Racioppi, M. Raidal, A. Salvio, A. Strumia

The paper studies inflation models whose Lagrangian does not contain any mass parameters. In the simplest one, the inflaton couples as S^2 R to gravity, and its expectation value after inflation generates the Planck scale. This model is excluded by the laters Planck and BICEP results.  However, the model can be saved by adding R^2 terms to the Lagrangian, as in  the Starobinsky R^2 inflation. 

Detecting Primordial B-Modes after Planck

P. Creminelli, D. L. Nacir, M. Simonović, G. Trevisan, M. Zaldarriaga

This paper estimates the sensitivity of future ground-based, balloon, and satellite CMB experiments to the tensor-to-scalar ratio r. Probing r down to 10^-3 should be possible in the future.