On Sunday, I woke to discover that I had won a major award: the Breakthrough Prize in Fundamental Physics. Well, not me personally, but the four main experimental collaborations of the Large Hadron Collider: ALICE, ATLAS, CMS, and LHCb. Together, that’s about 13,500 people, of which I represent about 0.008%. Still, my name is on the list of Laureates (about 2/3 of the way down the page), so it totally counts.
I actually didn’t know about it any sooner than you or anyone else: it’s quite hard to keep secrets in a collaboration of >5000 people, so understandably, only the spokesperson of the experiment and a small team preparing press releases were aware. But in this era of doom scrolling, I’ll take the unexpected good news 🙂
Some might say that it’s a bit odd that the LHC collaborations won a “breakthrough” prize when no new fundamental particles have been discovered since the Higgs boson (which incidentally was the last time that ATLAS and CMS won this prize!). Indeed, the fact that we haven’t found any evidence of new physics at the TeV scale is sometimes seen (and felt) as a sort of failure. But I think we should take this prize as a reminder that just because you don’t discover a new particle, doesn’t mean you aren’t shaking the foundations of science.
The fact we haven’t found any new particles or forces at the LHC, despite extensive searches and precision measurements in both the obvious and less obvious places (part of which I am responsible for coordinating), tells us something really fundamental. The lack of discovery itself is an interesting result, although sometimes we forget this fact. For instance, I’m reminded of an exchange I had with a theorist who took part in a panel discussion at the most recent ATLAS Exotics workshop. The theorist reminded us that at the turn of the millennium, you would have been hard-pressed to find a theorist who didn’t believe that supersymmetry was just around the corner. The common thinking was that we would turn on the LHC, find the Higgs boson, and then immediately find evidence of the first few supersymmetric particles. The theory was so elegant, it solved so many problems, made so much sense… how could it not be true? And if not supersymmetry, surely one of the other leading new physics models: lepto-quarks, Z’, vector-like quarks… one of these would surely be lying there waiting to be found. But that’s not what Nature chose for us. At this stage, if supersymmetry does exist at the TeV scale, it should be given an award for hide and seek. The same goes for most of the major models on the market. To remain viable, the particle masses need to be pushed up to beyond the TeV scale, or we need them to retreat to totally weird parameter configurations which cause more problems than they solve.
All this to say that the lack of a discovery at the LHC so far has completely revolutionized the thinking behind extensions to the Standard Model and has upended our collective view of the most likely explanation of the remaining mysteries of fundamental physics. Because if there really are no new particles to be found at the LHC, this has very serious implications for the nature of matter.
Back in the days leading up to the Higgs boson discovery, we were spoilt with the so-called “no-lose theorem”: either we discover a new particle or something else even more exciting must be there in its place. It was a very happy scientific situation, but one which we no longer have, and I think it’s fair to say that the field is having a hard time adapting to living without it. We experimentalists sometimes feel like we are in the doldrums, waiting for the wind to pick up again. But this breakthrough prize reminds us that every single null result we produce is valuable. Every time we look for a new particle and find nothing, we learn something new about the universe. Every time we measure a production cross-section, we are pushing back the boundaries of knowledge. And the LHC experiments produce hundreds of such results a year. I guess it takes someone from the outside awarding you a breakthrough prize you didn’t expect to remind you that your pile of null results is actually one of the greatest scientific goldmines ever imagined. And that the very next search might come up with the excess you’ve been waiting for.
Louie D. Corpe 