On July 4, 2012, a presentation held at CERN (European Center for Particle Physics) headquarters in Geneva, Switzerland, brought the discovery that would crown half a century of development of the so-called Standard Model: the Higgs boson.
And since then many, in academic circles and beyond, have been asking themselves — what’s next?
For Sérgio Novaes, a physicist at Unesp, this is the wrong focus. “We don’t do experiments to know what will happen, we always do the experiment to know if something will happen”, says the researcher, emphasizing the investigative nature of science.
Novaes is possibly the main Brazilian reference to talk about the Higgs boson and its historical importance. Not only was it part of the immense international collaboration linked to the LHC (Large Hadron Collider), a large CERN accelerator that made the discovery, signing the scientific article that presented it alongside hundreds of colleagues, but was the first in Brazil to write an article about the boson, when I was still in my master’s degree, exploring the mechanism that would reveal it four decades later.
Originally proposed in 1964 by Peter Higgs and five other scientists, distributed among three different teams, the Higgs boson (and its corresponding field) would prove essential to explain how other elementary particles gain their mass.
The proposal would prove to be fundamental for the development of the Standard Model, which today basically summarizes everything that is known about matter and three of the fundamental forces known in nature (the only force that it does not include, among those known, is gravity, the province of general theory of relativity).
Ironically, it was also the last piece of the Standard Model to be confirmed experimentally—48 years passed between the first prediction of its existence and its detection at the LHC. But considering the enormous success that the rest of the Standard Model has had in predicting new particles that would then be found in experiments, a common reading is that the “discovery” was merely a confirmation of what was already known. A big mistake, which Novaes works to undo on this ten-year anniversary. “Nobody spends billions of euros on a business you already know.”
At Unesp, to celebrate the occasion, he presents a lecture entitled “The untold story”, and the objective is to emphasize the size of the success in detecting the Higgs boson, remembering that, for a long time, instead of being something as “counted beans”, the proposition of their existence was considered by a good part of the physicist community as heresy or crazy. “There was huge resistance at the beginning, a strong struggle in the community, denying that and, even among those who didn’t deny it, no one knew what it was for.”
Now, with the Higgs discovered, the LHC continues to operate, exploring new possibilities. Faced with mysteries not covered by the Standard Model, such as dark matter and dark energy, physicists grope for clues as to where to proceed with their research. And there is hope that the experiments will bring answers.
But even if nothing new is discovered, Novaes highlights the importance of the work. “Our macro agenda is to try to go as deep as possible into the constituents of matter to understand them in the best possible way. This is an adventure that in itself justifies continuing the search”, he says. And he emphasizes that it doesn’t matter which country builds the next big particle accelerator; despite the disputes for prestige and hegemony, science will win.
His lecture to mark the tenth anniversary of the detection of the Higgs boson, at Unesp, is entitled “The untold story”. The story is that of the predictions, in the 1960s and 1970s, and that of the scientific discovery, announced by CERN in 2012, which won the Nobel Prize. What is the untold? The idea is to tell what it’s like to do science in real life. The fact that the proposals were deeply discredited at first.
Peter Higgs tells the story that in 1966, two years after he proposed the idea, he went to teach a seminar at Harvard. And Sidney Coleman, who was a super fun guy, I had the opportunity to share a room with him, later he said he “was anxious to rip this idiot to pieces”.
Higgs managed to avoid being called a lunatic, but he was unable to show that his work, then very controversial for contradicting “dogmas” of physics, was useful for anything. In other words, there was enormous resistance at the beginning, a strong struggle in the community, denying it and, even among those who did not deny it, no one knew what it was for.
Then in 1967 the [Steven] Weinberg does his study [que conduziria à criação do Modelo Padrão da FÃsica de PartÃculas], two and a half pages, 18,500 citations and a Nobel Prize. It’s absolutely fantastic. But he says as he proposes the model: “Of course our model has too many arbitrary parameters to make any predictions that could be taken seriously.”
From proposing the model to discovering the Higgs himself, researchers have spent a lot of time trying to find a viable alternative.
And how did the search for the Higgs boson actually begin? In 1975, years after the original Higgs proposal, John Ellis and colleagues make the first phenomenological study.
It’s a 45-page study where they end up saying, “Look, we apologize to the experimental people, we have no idea what the boson’s mass is, and we also don’t know exactly what its coupling to other particles is. These are things the model doesn’t predict. For these reasons, we don’t want to encourage large experimental searches for the Higgs boson, but we feel that people performing experiments vulnerable to the Higgs boson should know how it might appear.”
And then the following happened: the success of the model became thunderous. New particles were being discovered, the W and Z bosons, and everything was falling into place in an absurdly fantastic way, except for the Higgs boson. How can a situation like this? It is an object that has to be pursued.
The hard part was not knowing what energy level, what mass range, to look for. Why are experimentalists left in the dark? I say the following: we don’t do experiments to know what will happen, we always do the experiment to know if something will happen. We had the question, where is the Higgs boson. And the LEP (European accelerator before the LHC), if it had had a little more energy, it would have found it. There were even some suspicious events. And it became a fight with the director of CERN, whether to keep the LEP on or off to install the LHC. They are located in exactly the same physical tunnel. So I had to dismantle the LEP to build the LHC. The LEP, its limit reached 115 GeV (gigaelectron volts). And the Higgs boson appeared at 125, 126 GeV.
And then we entered a phase, already talking about the last ten years, which is about what comes next. His colleague at Unesp, Rogério Rosenfeld, often cites a syndrome called PHD, “Post-Higgs Depression”, or post-Higgs depression. Because now the Standard Model is closed, this is resolved, but there are signs that there is physics beyond the Standard Model. Dark matter, dark energy, a host of problems yet to be tackled, and experimentalists find themselves in a situation perhaps similar to the 1960s, 1970s, where you had all sorts of models, but you didn’t have enough experimental support to pick a favorite. . Is it a valid parallel between what was happening then and now? So-so. Let me make a personal statement here. I’ll take the same PHD and say that I suffered from “Pre-Higgs Depression”, pre-Higgs depression. Because I made a pretty strong career change.
I started my career by publishing an article in my master’s degree that I consider, until proven otherwise, the first on the Higgs published in Brazil, and I was very happy to have published the article on the exact mechanism that came to produce it 40 years later. .
I followed a career as a theorist and there came a time when I said, listen, that’s not where the solution to anything will come from, because the scientist’s imagination is a very rich thing and we are trying to explore increasingly crazy things, more and more in a direction that we don’t know where we’re going, and who can answer that? It can only be the experiment. And I went to become an experimental in the middle of my career, after 20 years.
Having said that, I think today is stronger [que no passado], because there we did as much physics as possible. The Standard Model proposal is very strong today, it is difficult to find a gap. But we are working on dark matter. Our line of research in exotic physics has been the search for dark matter at the LHC.
And do you think you will find it? I’m not sure, I’m not going to put my feelings here because they are…
Please place them. From your tone, it sounds like you think the Standard Model is so round that, from your point of view, it’s more comfortable to question the astrophysical evidence for dark matter. Is it more or less there? It is clear that everyone will defend theirs, that the evidence is solid and that there is no other way. Is that so. Everything is fine. Now, it might not be a particle, you know? It is not necessarily a particle. I don’t know what it could be. If I knew, I would be here writing the study to buy a ticket to Stockholm. It could be something completely new. But it is our moral and scientific obligation to insist that, if it is a particle, it should probably manifest itself in the kind of collisions we make.
How successful is the discovery of the Higgs boson ten years later? Huge victory. Nowadays, there’s an attitude that kind of considers this big win a thing of the past. “Oh, that’s what we already knew we had.” That can’t either, see? That’s why the title of my talk is that. That’s not how it happened. Nobody spends billions of euros on a business you already know.
Finally, I wanted to ask about the future of particle physics. The Chinese have been talking about building an accelerator more powerful than the LHC. Americans and Europeans have not yet taken this step, although ideas abound. The double question: do we need a more powerful accelerator, and if it is built, is it likely to be in China? It’s a complex question, but I don’t want to give it an easy answer. Why are more accelerators built? For two reasons.
First, if there are heavier particles, it takes more energy. And to penetrate farther and farther into matter, more energy is needed. So, our macro agenda is to try to go as deep as possible into the constituents of matter in order to understand them in the best possible way. This is an adventure that alone justifies continuing the quest. You don’t have to make an agenda made to sell you dark matter, dark energy. It’s that famous phrase from Wilson, director of Fermilab, asked by US congressmen about laboratory expenses. They asked him if the investment would help the country’s defense in any way. He replied no, but it would make the country worth defending.
As for the Chinese project, it still doesn’t have a consolidated proposal, and their war is one of hegemony, with the US. And they know, unlike us, that science plays an extremely important role. If we manage to overcome the economic difficulties, the US has proposals to make accelerators, Europe has it, China has it, and it’s great that everyone has it and that the best option wins.
X-ray
Sergio Ferraz Novaes, 66
Professor at Unesp (Universidade Estadual Paulista), in São Paulo, he is a member of the Compact Muon Solenoid (CMS) collaboration, one of the four experiments installed at the LHC (Large Hadron Collider), the CERN (European Center for Particle Physics) accelerator responsible for for the discovery of the Higgs boson. He is a principal researcher at the São Paulo Research and Analysis Center (SPRACE), and his team has implemented GridUnesp, the first Grid Campus in Latin America. He is the Brazilian representative on the Particles and Fields Commission of the International Union of Pure and Applied Physics and technical-scientific director of the Steering Committee of the Center for Technological Research in Oil and Gas of the Santos Basin.
