Two weeks ago, I travelled to Prague in the Czech Republic, where more than 1400 scientists had descended on the city for one of the biggest events in the particle-physics calendar. I was attending the International Conference on High Energy Physics (ICHEP), which takes place every two years and attracts scientists from all over the world.
Almost 1000 parallel talks were crammed into the first three days of the week-long conference, and with 13 parallel sessions, I kept myself fit running between floors to catch everything I wanted to see. I tried to see a bit of everything, from Higgs physics to neutrinos and from future colliders to cosmology.
As well as presentations of scientific results, the event featured discussions about equality diversity and inclusion (EDI), education and outreach, all relatively new additions to the conference programme.
This was also the first ICHEP with a dedicated stream on sustainability. I spoke to Jorgen D’Hondt, a professor at Vrije University Brussels, who delivered a presentation about the “Innovate for Sustainable Accelerator Systems” project. Climate change has brought energy consumption to the forefront of all our minds and particle physics is no exception. D’Hondt argued that particle physicists have a responsibility to make their experiments, many of which will operate decades into the future, as efficient as possible.
“I don’t think people in the 2040s will ask us whether we are using green energy. Because by that time most of the energy will be green” said D’Hondt. “I believe the question of that generation will be can we as scientists demonstrate that our facilities have done all they can to reduce our energy footprint.”
After three hectic days of parallel sessions, I was grateful that the second half of the conference gave me a chance to rest my feet. We settled into a huge theatre for the plenary talks, which were longer than the parallel sessions, but each speaker still had the difficult task of condensing several years of research in their field into a 25-minute slot.
When I was asked by attendees what I was doing at ICHEP, my stock answer was that I was there to discover where the next big discovery – on a par with the Higgs boson – will come from. It’s no surprise therefore that my ICHEP highlight was a panel debate on future colliders.
The discussion featured the heads of four of the world’s biggest physics labs: Fabiola Gianotti (CERN), Lia Merminga (Fermilab in the US), Yifang Wang (from the Institute of High Energy Physics (IHEP) in China) and Shoji Asai (the High Energy Accelerator Research Organization (KEK) in Japan.
From dark energy to the asymmetry between matter and antimatter, we’ve discovered that the standard model has some serious limitations, and the search is on for new physics. The big question for the panel was where, and who, this will come from.
From what I saw, the frontrunner experiment is undoubtably a “Higgs factory”. Higgs bosons have been linked to many of the puzzling gaps in the Standard Model of particle physics and a Higgs factory is a collider that would produce them at a high rate, allowing their properties to be measures with great precision.
All the organizations represented on the panel have expressed interest in building such an experiment, and Wang was particularly optimistic about China’s ability to follow through on their proposal, the Circular Electron Positron Collider (CEPC), saying “we have a mission to be one of the world leaders in particle physics”.
He also acknowledged that this could put IHEP in competition with CERN, which has its own proposal for a similar experiment called the Future Circular Collider (FCC). Perhaps the elephant in the room during this discussion was the impact that future diplomatic relations, particularly between the US and China, could have on these collider projects – something that came up frequently in other discussions during the conference.
Not everyone I spoke to was convinced that the Higgs factory should be prioritized by the field, and I saw many innovative proposals for smaller experiments. What makes particle physics so exciting is that while we’re pretty sure new physics is out there, no-one knows for sure where we should be looking for it.
While some are impatient for another big break, it’s only been 12 years since the discovery of the Higgs boson – a relatively short time in a field that is always looking several decades into the future. I’ll be keeping a watchful eye for big decisions in the next few years, as high-energy physics finds its next steps.
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