10 years Higgs: interview with Nicolo de Groot

‘This particle is like a crowbar’

Nicolo de Groot, professor at Radboud University Nijmegen, then program leader ATLAS at Nikhef

‘Like many colleagues, I was at Nikhef that Wednesday, watching the live stream from Geneva. My emotion was one of relief. Finally! My master’s thesis was about Higgs. My first publication. All my research since then. After all these years of work, this was a wonderful moment.

With my PhD student Antonio Salvucci, I had worked in the lead-up to the search for Higgs particles decaying to four leptons. Nikhef was good at muon chambers and the software. Four leptons is a very clean decay, with little background. But if you select too strictly it’s not very efficient. In 2011 we had very little because of that. But we let go of the criteria a bit and saw the data trickle in.

The Higgs peak gradually took shape in the weeks before July. Some of the plots that Fabiola Gianotti showed in the presentation on July 4 on behalf of ATLAS had been made by Antonio. He had talked her through the details a few days before. Another result from Nikhef, Higgs to two W particles, unfortunately didn’t make it into the presentation, but fortunately did make it into the discovery paper a month later.

I think the Higgs particle has turned out to be even more important than we thought 10 years ago. Back then we were hoping for many more unknown particles at the LHC accelerator. That didn’t happen and so the Higgs particle is our main crowbar to crack the Standard Model with.

If I were to get an answer for sure, I would ask this of a Higgs particle: do you also couple to neutrinos? Neutrinos have hardly any masses, we know that. But does that also mean no link to Higgs? We don’t know that and it intrigues me a lot. My deepest wish? That one day we manage to make a map of the cosmic neutrinos from half a second after the Big Bang. The real baby picture of our universe. A work in progress.’

This interview was originally published in Nikhef magazine DIMENSIES #7

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