3rd
New Physics @ CDF?!?!
This has the potential to be big. To cut to what the abstract says is that they are essentially seeing muon production WELL outside the beam pipe(if you read the paper this is via the fact that there’s a long tail on the distribution of muon impact parameters-out to several centimeters.) In most proton-antiproton interactions you get muon production near the vertex not several centimeters away. If they do rule out any background or triggering issues there can be really only one explanation: new physics. And totally unexpected new physics at that. If you’re seeing muon proudction that far from the vertex there’s some particle that’s gone unobserved that is then decaying (and probably decaying again) where you then get this tertiary leptonic jet. Very surprisingly, Neil Weiner and Nima Arkani-Hamed have a recent paper that came out a few weeks ago that could lend an explanation on what’s going on. From their abstract:
“A completely generic prediction is that G_Dark particles(generated by a broken gauge symmetry at the GeV scale) can be produced in cascade decays of MSSM superpartners, since these end with pairs of MSSM LSP’s that in turn decay into the true LSP and other particles in the dark sector. In turn, the lightest GeV-scale dark Higgses and gauge bosons eventually decay back into light SM states, and dominantly into leptons. Therefore, a large fraction of all SUSY events will contain at least two “lepton jets”: collections of n>= 2 leptons, with small angular separations and GeV scale invariant masses.
This is some really exciting stuff if it turns out to be true. A slightly more in depth and technical discussion can be found here.
Glossary:
MSSM: Minimal Supersymmetric Standard Model.
LSP: Lightest supersymmetric particle
GeV: Gigaelectronic volt
SM: Standard Model
Lepton: A family of fundamental particles. They are not made of quarks (electrons, muons, taus).
Broken symmetry: I wrote about broken symmetries a bit here.
