Hope for SUSY fades at 8 TeV

Still looking for SUSY: the LHCb detector and its team of physicists. (Courtesy: CERN)

By Hamish Johnston

After the historic announcement of the Higgs discovery in July, things have gone very quiet at the Large Hadron Collider (LHC). Although the facility in Geneva has been colliding protons like gangbusters, there is very little buzz about what the next big discovery will be.

I was hoping that this would change this week at the Hadron Collider Conference in Kyoto, where the latest results are being discussed. However, a big disappointment – at least for fans of supersymmetry (SUSY) – came on Monday, when physicists working on the LHCb experiment announced that they have measured a rare decay of the B_s particle.

There was a hope that the decay of the B_s to a muon and antimuon would point towards SUSY – a collection of theories that go beyond the Standard Model of particle physics. SUSY is an attractive concept because it offers a solution to the “hierarchy problem” of particle physics, provides a way of unifying the strong and electroweak forces, and even contains a dark-matter particle.

But alas, the B_s decay seems to be best described by the Standard Model and SUSY remains as elusive as ever. Indeed, it looks like we might have to wait until the collision energy at the LHC is boosted from the current 8 TeV to 14 TeV – which will occur when the collider is shut down over 2013–2014.

The LHCb team has uploaded a preprint of its B_s paper to arXiv.

Bloggers are also chattering about the result. Peter Woit puts SUSY in intensive care, whereas Gordon Kane argues that the measurements are still compatible with some types of SUSY. Meanwhile, Matt Strassler can always be relied upon to take a more measured approach.

And what about the Higgs? The lack of gossip on this front seems to suggest that the new data are showing that the LHC’s Higgs particle is also best described by the Standard Model – more to come from Kyoto tomorrow on that front.