Dark matter at the LHC

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With the advent of modern particle cosmology, particle physics and astrophysics have moved closer together than ever before. Discoveries in particle physics have direct consequences for our understanding of the cosmos - for instance, the expansion history of the Universe depends crucially on the number and masses of elementary particle species.The see-saw mechanism for neutrino mass generation, together with the dynamics of the electroweak theory, is the basis for leptogenesis, which could provide an explanation for the observed baryon asymmetry of the Universe. Similarly, astrophysical and cosmological observations are among the most sensitive tools for studying elementary particles, providing for instance the strongest limits on neutrino masses.The most widely sought-after connection between astrophysics and particle physics is the nature of dark matter (DM). While its particle physics nature is still unknown, there are reasons to believe that its mass, as well as the masses of any other new particles responsible for its coupling to SM fields, is at the electroweak scale, and its couplings are similar to the SM gauge couplings. In this scenario, often called the "WIMP (weakly interacting massive particle) miracle", the observed abundance of DM in the Universe can be understood through thermal freeze-out. Most crucially for particle physics, this would also imply that direct production of DM is within reach of the LHC. There, DM production would leave telltale traces in form of signatures with missing transverse energy.A number of potential signals from direct and indirect DM searches could point towards DM particles around the electroweak scale. Perhaps the most notable of these signals is the excess gamma ray flux from the Galactic Center region [11-13], which can be explained by annihilation of an O(40 GeV) DM particle to b quarks or leptons. While the gamma ray excess, as well as the other anomalous signals discussed in the literature, may be due to underestimated experimental or astrophysical backgrounds, it is intriguing that some of these signals could point towards DM physics within reach of the LHC.