10 years Higgs: interview with Ivo van Vulpen

‘I suddenly thought: it is really true’

Ivo van Vulpen, deputy programme leader ATLAS at Nikhef, senior lecturer at the University of Amsterdam

‘I was at home in Leiden after knee surgery, but Nikhef kindly arranged a taxi so I could be in Amsterdam for the live stream of the announcement. It was a very exciting moment, with champagne for the colleagues, and rightly so. The emotion of that moment was actually quite crazy. For years I had been lecturing particle physics to master’s students, neatly explaining symmetry breaking and the Higgs mechanism. I remember literally thinking on July 4: so it’s all really true! The most mythical particle in physics exists. So there was really a field that permeates every cubic meter of the universe and shapes the universe to this day. That does something to you.

My role in the discovery was not very big, although my name is on the paper. I worked with a PhD student, Egge van der Poel, on a technique to find four muons from the same collision between all of them. The idea was that a Higgs particle decays to two Z particles, each of which decays into two muons. We were really working with the very first data, which was kind of a kick. Later, others picked up on that and Higgs to ZZ became an important channel in the discovery.

Nowadays, Higgs particles are perfectly normal, the LHC produces them constantly and ATLAS sees their tracks. My research is focused on the lifetime of the Higgs particle. Theoretically it is well known. If we find anomalies, it could be a sign that unknown particles are involved. The lifetime is just one of countless properties of the Higgs particle that we will have to study for years to really understand what this thing is.

So my question to the Higgs particle is: are there heavier particles that you also give mass to but that we don’t see yet? In that respect, any new discovery is welcome.’

This interview was originally published in Nikhef magazine DIMENSIES #7

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