Finally Something Possibly Interesting…

The two big LHC experiments ATLAS and CMS just released some of their first results from LHC Run 2, which is the newest run and the first at close to the design energy of 14 TeV.

I missed streaming the talks live and haven’t had time to track down the videos or slides yet, but everyone is buzzing about one thing in particular: a small excess seen in both experiments in the diphoton channel at a center of mass energy near 1.5 TeV (note: going over the slides now and it looks like Nature has embarrassingly completely misunderstood the plots. The peak is at 750 GeV). The result is quoted at a few sigma significance for each experiment, so the combined result won’t be high enough to show anything definitive at will be lowered somewhat by the “look elsewhere” effect, where the true significance of an excess in such a global search is actually lower than the apparent local significance (i.e. if you make enough measurements you’ll always find some large deviation from your expectation).

A peak in the diphoton channel potentially points to a new heavy neutral boson. This could be one of the many predicted bosons in various models of beyond the Standard Model physics or it could be something completely new. If the result holds up and it really is some new elementary particle (it’s far heavier than even the top, so if the excess is real, it’s probably not a bound state of known particles), it would be very exciting news for the field. That would be the first truly new particle found since the development of the Standard Model. Figuring out what it is and where it comes from would then clearly be one of the highest priority tasks for experimentalists over the next few decades.

There still aren’t any signs of supersymmetric particles like squarks and gluinos, making it even harder to fit minimal supersymmetry with current measurements.

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