Back in the California Gold Rush, many people panning for gold saw a yellow glint at the bottom of their pans, and thought themselves lucky. But more often than not, it was pyrite — iron sulfide — fool’s gold…
Back in December 2015, a bunch of particle physicists saw a bump on a plot. The plot showed the numbers of events with two photons (particles of light) as a function of the “invariant mass” of the photon pair. (To be precise, they saw a big bump on one ATLAS plot, and a bunch of small bumps in similar plots by CMS and ATLAS [the two general purpose experiments at the Large Hadron Collider].) What was that bump? Was it a sign of a new particle?
A similar bump was the first sign of the Higgs boson, though that was far from clear at the time. What about this bump?
As I wrote in December,
“Well, to be honest, probably it’s just that: a bump on a plot. But just in case it’s not…”
and I went on to describe what it might be if the bump were more than just a statistical fluke. A lot of us — theoretical particle physicists like me — had a lot of fun, and learned a lot of physics, by considering what that bump might mean if it were a sign of something real. (In fact I’ll be giving a talk here at CERN next week entitled “Lessons from a Flash in the Pan,” describing what I learned, or remembered, along the way.)
But updated results from CMS, based on a large amount of new data taken in 2016, have been seen. (Perhaps these have leaked out early; they were supposed to be presented tomorrow along with those from ATLAS.) They apparently show that where the bump was before, they now see nothing. In fact there’s a small dip in the data there.
So — it seems that what we saw in those December plots was a fluke. It happens. I’m certainly disappointed, but hardly surprised. Funny things happen with small amounts of data.
At the ICHEP 2016 conference, which started today, official presentation of the updated ATLAS and CMS two-photon results will come on Friday, but I think we all know the score. So instead our focus will be on the many other results (dozens and dozens, I hear) that the experiments will be showing us for the first time. Already we had a small blizzard of them today. I’m excited to see what they have to show us … the Standard Model, and naturalness, remain on trial.