Matt Strassler 11/1/11. No rest for the weary: yet another discrepancy. This one is somewhat different from the small multi-lepton excess at CMS of a couple of weeks ago (tenuous, but in a very interesting and plausible place) and from the OPERA faster-than-light neutrino claim (not so tenuous, but not so plausible either). Now we have a discrepancy involving collisions that produce two low-energy photons [particles of light]. The effect is seen in four experiments, not one: both ATLAS and CMS at the Large Hadron Collider (LHC), and also CDF and DZero at the Tevatron collider. It’s too large to be a statistical fluke (the excess is not small and it shows up in four experiments). Nor does it look like an experimental mistake (since it shows up in four experiments). Might it be a sign of a new phenomenon not predicted by the Standard Model (the equations that describe the known particles and forces, plus the simplest possible Higgs particle)? Maybe… Can’t rule it out, though there’s not enough information in the experiments’ public documents for a serious evaluation of that possibility. But in any case, my preliminary impression is that it’s most likely something else: either a problem with the theoretical calculation of what the Standard Model predicts, or a problem with the way this theoretical calculation was used by the experiments.
Now why would I come to that conclusion? To read more, click here.