The Fermi collaboration released yesterday a paper describing their measurement of the electron and positron flux of cosmic rays. Simultaneously, a second paper was published by the HESS collaboration on the very same topic. Together, these two important new articles provide the means for a significant advancement in our understanding of the spectrum of electrons and positrons from nearby sources.

It is especially meaningful to consider the two results together because the two instruments are as different as salt grains and tequila. Let me see where to start:

Triggered by a preprint appeared three days ago on the ArXiV -a fundamental resource for particle physicists willing to stay in touch with the latest developments of the theory and new experimental results-  this morning I was gearing up to write a post with a careful, didactical discussion of why we believe that the subnuclear world includes three generations of quarks and three generations of leptons, what is the evidence for this peculiar fact, and what would a fourth generation of matter imply for e.g. searches of the Higgs boson. Unfortunately, my memory is still good enough to let me remember that I did write about those things in my old blog, about one year ago.