Abstract: Protons and helium nuclei are the most abundant components of the cosmic radiation. Precise measurements of their fluxes are needed to understand the acceleration and subsequent propagation of cosmic rays in the Galaxy. We report precision measurements of the proton and helium spectra in the rigidity range 1 GV-1.2 TV performed by the satellite-borne experiment PAMELA. We find that the spectral shapes of these two species are different and cannot be well described by a single power law. These data challenge the current paradigm of cosmic-ray acceleration in supernova remnants followed by diffusive propagation in the Galaxy. More complex processes of acceleration and propagation of cosmic rays are required to explain the spectral structures observed in our data.

A challenge for Cold Dark Matter

In a recent paper (see the arXiv version here) Stacy Mc Gaugh has obtained an observational result (tight correlation between the rotation velocity and baryonic mass, a.k.a. Baryonic Tully-Fisher Relation) that challenges the standard LambdaCDM model, and appears to favor instead the so-called MOdified Newtonian Dynamics (MOND) theory.

MOND is known to provide an excellent explanation of astrophysical observations of Galactic scales, and in the framework of this theory it is possible to get rid of the Dark Matter hypothesis through a suitable modification of the law of Gravity. However, it is also known that MOND does NOT provide a satisfactory explanation of clusters, and needs dark matter (‘massive’ neutrinos are often invoked) to explain lensing observation on these scales.

Independently form Mond, this result represents a new challenge for the Cold Dark Matter model (that, let’s not forget, otherwise performs well on many astrophysical ad cosmological observations).

LHC early constraints on SUSY

The first analyses of the impact of early LHC data on the parameter space of Supersymmetry (SUSY) have been presented at several winter conferences.

The results the ATLAS and CMS papers have been recently posted on the arXiv (here and here), and they are actually based on 35 pb-1 of LHC data at 7 TeV.

A good discussion of their impact on SUSY can be found in the blogosphere at Resonaances and in Tommaso Dorigo’s blog. For technical discussions see also the papers of A. Strumia and B. Allanach.

Looks like the moment of truth is coming for SUSY, and more in general for WIMP Dark Matter.