Tag: Atomki

My heart of physics

Every July 4, I have occasion to remember two things: the discovery of the Higgs boson, and my first published byline for an article about the discovery of the Higgs boson. I have no trouble believing it’s been eight years since we discovered this particle, using the Large Hadron Collider (LHC) and its ATLAS and CMS detectors, in Geneva. I’ve greatly enjoyed writing about particle physics in this time, principally because closely engaging with new research and the scientists who worked on them allowed me to learn more about a subject that high school and college had let me down on: physics.

In 2020, I haven’t been able to focus much on the physical sciences in my writing, thanks to the pandemic, the lockdown, their combined effects and one other reason. This has been made doubly sad by the fact that the particle physics community at large is at an interesting crossroads.

In 2012, the LHC fulfilled the principal task it had been built for: finding the Higgs boson. After that, physicists imagined the collider would discover other unknown particles, allowing theorists to expand their theories and answer hitherto unanswered questions. However, the LHC has since done the opposite: it has narrowed the possibilities of finding new particles that physicists had argued should exist according to their theories (specifically supersymmetric partners), forcing them to look harder for mistakes they might’ve made in their calculations. But thus far, physicists have neither found mistakes nor made new findings, leaving them stuck in an unsettling knowledge space from which it seems there might be no escape (okay, this is sensationalised, but it’s also kinda true).

Right now, the world’s particle physicists are mulling building a collider larger and more powerful than the LHC, at a cost of billions of dollars, in the hopes that it will find the particles they’re looking for. Not all physicists are agreed, of course. If you’re interested in reading more, I’d recommend articles by Sabine Hossenfelder and Nirmalya Kajuri and spiralling out from there. But notwithstanding the opposition, CERN – which coordinates the LHC’s operations with tens of thousands of personnel from scores of countries – recently updated its strategy vision to recommend the construction of such a machine, with the ability to produce copious amounts of Higgs bosons in collisions between electrons and positrons (a.k.a. ‘Higgs factories’). China has also announced plans of its own build something similar.

Meanwhile, scientists and engineers are busy upgrading the LHC itself to a ‘high luminosity version’, where luminosity represents the number of interesting events the machine can detect during collisions for further study. This version will operate until 2038. That isn’t a long way away because it took more than a decade to build the LHC; it will definitely take longer to plan for, convince lawmakers, secure the funds for and build something bigger and more complicated.

There have been some other developments connected to the current occasion in terms of indicating other ways to discover ‘new physics’, which is the collective name for phenomena that will violate our existing theories’ predictions and show us where we’ve gone wrong in our calculations.

The most recent one I think was the ‘XENON excess’, which refers to a moderately strong signal recorded by the XENON 1T detector in Italy that physicists think could be evidence of a class of particles called axions. I say ‘moderately strong’ because the statistical significance of the signal’s strength is just barely above the threshold used to denote evidence and not anywhere near the threshold that denotes a discovery proper.

It’s evoked a fair bit of excitement because axions count as new physics – but when I asked two physicists (one after the other) to write an article explaining this development, they refused on similar grounds: that the significance makes it seem likely that the signal will be accounted for by some other well-known event. I was disappointed of course but I wasn’t surprised either: in the last eight years, I can count at least four instances in which a seemingly inexplicable particle physics related development turned out to be a dud.

The most prominent one was the ‘750 GeV excess’ at the LHC in December 2015, which seemed to be a sign of a new particle about six-times heavier than a Higgs boson and 800-times heavier than a proton (at rest). But when physicists analysed more data, the signal vanished – a.k.a. it wasn’t there in the first place and what physicists had seen was likely a statistical fluke of some sort. Another popular anomaly that went the same way was the one at Atomki.

But while all of this is so very interesting, today – July 4 – also seems like a good time to admit I don’t feel as invested in the future of particle physics anymore (the ‘other reason’). Some might say, and have said, that I’m abandoning ship just as the field’s central animus is moving away from the physics and more towards sociology and politics, and some might be right. I get enough of the latter subjects when I work on the non-physics topics that interest me, like research misconduct and science policy. My heart of physics itself is currently tending towards quantum mechanics and thermodynamics (although not quantum thermodynamics).

One peer had also recommended in between that I familiarise myself with quantum computing while another had suggested climate-change-related mitigation technologies, which only makes me wonder now if I’m delving into those branches of physics that promise to take me farther away from what I’m supposed to do. And truth be told, I’m perfectly okay with that. 🙂 This does speak to my privileges – modest as they are on this particular count – but when it feels like there’s less stuff to be happy about in the world with every new day, it’s time to adopt a new hedonism and find joy where it lies.

UCal Irvine’s ‘fifth force’ farce

A screenshot of the UCI press release in question. Source: UCI
A screenshot of the UCI press release in question. Source: UCI

Michael Moyer just concluded a rant on Twitter (at the time of writing this) about how a press release on a recent theoretical physics result developed at the University of California, Irvine, had muddled up coverage on an important experimental particle physics result. I was going to write about this in detail for The Wire but my piece eventually took a different route, so I’m going to put some of my thoughts down on the UCI fuck-up here.

Let’s begin with some background: In April 2015, a team of nuclear physicists from the Hungarian Academy of Sciences (Atomki) announced that they had found an anomalous decay mode of an unstable beryllium-8 isotope. They contended in their paper, eventually published in Physical Review Letters in January 2016, that the finding had no explanation in nuclear physics. A team of American physicists – from the University of California, Irvine, and the University of Kentucky, Lexington – picked up on this paper and tried to draw up a theory that would (a) explain this anomaly even as it (b) would be a derivative of existing theoretical knowledge (as is the work of most theoretical physics operating at the edge). There are many ways to do this: the UCI-UKL conclusion was a theory that suggested the presence of a new kind of boson, hitherto undiscovered, which mediated the beryllium-8 decay to give rise to the anomalous result observed at Atomki.

Now, the foreground: A UCI press release announcing the development of the theory by its scientists had a headline that said the Atomki anomalous result had been “confirmed” at UCI. This kicked off a flurry of pieces in the media about how a ‘fifth force’ of nature had been found (which is what the discovery of a new boson would imply), that all of physics had been overturned, etc. But the press release’s claim was clearly stupid. It was published no more than a week after the particle physics community found out that the December 2015 digamma bump at the LHC was shown to be a glitch in the data, when the community was making peace with the fact that no observation was final until it had been confirmed with the necessary rigour even if physicists had come up with over 500 theoretical explanations for it. The release was also stupid because it blatantly defied (somewhat) common sense: how could a theoretical model built to fit the experimental data “confirm” the experimental data itself?

There’s even a paragraph in there that makes it sound like the particle’s been found! (My comments are in square brackets and all emphasis has been added:)

The UCI work demonstrates [misleading use] that instead of being a dark photon, the particle may be a “protophobic X boson.” While the normal electric force acts on electrons and protons, this newfound [the thing hasn’t been found!] boson [a boson is simply one interpretation of the experimental finding] interacts only with electrons and neutrons – and at an extremely limited range. Analysis co-author Timothy Tait, professor of physics & astronomy, said, “There’s no other boson that we’ve observed that has this same characteristic. [Does this mean UCI has actually observed this particular boson?] Sometimes we also just call it the ‘X boson,’ where ‘X’ means unknown.”

Moyer says in one of his tweets that PR machines will always try to hype results, outcomes, etc. – this is true, and journalists who don’t cut through this hype often end up writing flattering articles devoid of criticism (effectively missing the point about their profession, so to speak). However, as far as I’m concerned, what the UCI PR has done is not build hype as much as grossly mislead journalists, and I blame the machine in this case more than the journalists who wrote the “fifth force found” headlines. Journalism is already facing a credibility crisis in many parts of the world without having to look out for misguided press releases from universities of the calibre of UCI. Yes, such easily disturbed qualities are also often trusted by journalists, or anyone else, because we trust institutional authorities to take such qualities seriously themselves.

(Another such quality is ‘reputation’. Nicholas Dirks just quit because his actions had messed with the reputation of UCal Berkeley.)

This is a problem exacerbated by the fact that journalism also has a hard time producing – and subsequently selling – articles about particle physics. Everyone understands that the high-energy physics (HEP) community is significantly invested in maintaining a positive perception of their field, one that encourages governments to fund the construction of mammoth detectors and colliders. One important way to maintain this perception is to push for favourable coverage in the mainstream media of HEP research and keep the people – the principal proxy for government support – thinking about HEP activities for the right reasons. The media, in turn, can’t always commission pieces on all topics nor can it manufacture the real estate even if it has the perfect stories; every piece has to fight it out. And in crunch times, science stories are the first to get the axe; many mainstream Indian publications don’t even bother with a proper science section.*

If, in this context, a journalist buys into a UCI press release about some kind of ‘confirmation’ of a fifth force, and which is subsequently found to be simply false, an editor wouldn’t be faced with a tough choice whatsoever about which section she has to axe.

What happens next? We wait for experimental physicists try to replicate the Atomki anomaly in experiments around the world. If nothing else, this must happen because the Atomki team has published claims of having discovered a new particle at least twice before – in 2008 and 2012 – both at a significance upwards of 3 sigma (i.e., the chances of the results being a fluke being 1 in 200,000). This is a statistical threshold accepted by the particle physics community and which signifies the point at which a piece of data becomes equivalent to being evidence. However, the problem with the Atomki results is that both papers announcing the discoveries were later retracted by the scientists, casting all their claims of statistical validity in doubt. The April 2015 result was obtained with a claimed significance of 6.8 sigma.

*Even The Hindu’s science page that used to appear every Thursday in the main newspaper was shunted last year to appear every Monday in one of its supplements. It never carried ads.