An intriguing experimental result was announced today by the Fermilab particle accelerator. I was going to sit down and write a layman’s account of what the finding indicates, but happily Stephen Barr has beat me to it. He states it all quite clearly, and I recommend his article if you’re interested in these things. My doctoral work was related to the physics under consideration in this experiment, so it is especially interesting for me to see this surprising result.
Essentially — glossing over all the details — they are claiming to have observed a physical process which, if confirmed, would indicate, really for the first time in decades, that the Standard Model of particle physics is incomplete. (We know on other grounds that it is incomplete, but I believe that this would be the first time a laboratory experiment produced a result that was not consistent with the Standard Model and could not be fixed with a minor tweak.) It would indicate that some new physics — a new force or new particles previously unknown — was being (indirectly) detected.
Barr makes two good points that I’ll re-iterate. First, this experimental result could be a statistical fluctuation, and might go away as more data is collected; it does not yet meet the stringent standards for an official “discovery” in the particle physics community. Second, the heavy breathing in the newspapers (such as in the NYT article linked above) about how this result explains “existence” is sheer puffery. If it holds up it is certainly important, and it has implications for cosmology, but it is not metaphysical. Obviously.
The official publication from Fermilab’s DØ experiment is here. For a good one-slide summary of how this result compares to previous experimental results and the Standard Model expectation, look at slide 46 of this talk.
UPDATE: A kind reader, Vince, sends an update on this matter: another of the Fermilab experiments, CDF, has now published their measurement of the same quantity, with higher statistics, and they find it consistent with the Standard Model. So it is likely that the DØ result will go away with more data. Too bad. Thanks, Vince.