Stop sign

Now that the Higgs boson has (apparently) been discovered at the Large Hadron Collider, physicists are turning their attention to the next big thing. Theorists have long predicted that the LHC would produce supersymmetric particles, but these have so far failed to make an appearance. There was some hope that data would show signs of the stop particle (the supersymmetric partner of the top quark) but that too appears to be fading.

Yesterday Michael Peskin gave a talk in which he argued that the LHC evidence did not imply that supersymmetry was dead – only that we needed a bigger accelerator, such as the International Linear Collider. His argument was in part based on the “sociological evidence” that “1. No theorist who believed in SUSY before 2009 has renounced SUSY in the light of the LHC exclusions,” and “2. Model builders are still building models with 200 GeV charginos.”

As someone who is interested in the sociology of scientific prediction, I would argue that the fact that theorists do not renounce their beliefs due to lack of experimental confirmation, or refrain from building models, is not exactly convincing proof that a theory is right.

A safer prediction is that supersymmetry will remain attractive for a long time yet – in large part because of its aesthetic qualities – and will continue to be used as an argument for larger accelerators. The lack of a stop at current energies is just a green light.

New boson!

Biggest day in physics for the last half century or so, as new results from the CMS and ATLAS experiments at the Large Hadron Collider confirm the discovery of a new boson, consistent (so far) with the expected properties of the Higgs boson.

According to CMS spokesperson Joe Incandela, “What we are observing is very likely a new particle with very large mass that would have to be a boson. This is potentially an historic and very profound step forward in our understanding of the underlying structure of our universe.”

Andy Lankford, deputy spokesperson of ATLAS: “If the new particle is determined to be the Higgs, attention will turn to a new set of important questions. Is this a Standard Model Higgs, or is it a variant that indicates new physics and other new particles?”

The Higgs field, for which this boson may be the associated particle, is believed to be responsible for giving other particles their mass. Of course, this leaves open the question of why different particles interact with the Higgs field in different ways. Why are muons relatively hefty, electrons light, and photons massless? One of the next goals for physicists will be to figure this out (unless of course it is just that some particles interact more strongly because they are heavy …).