Confirmed: That Was Definitely the Higgs Boson Found at LHC

By Amir Aczel | June 25, 2014 8:28 am

higgs boson

Ever since the 2012 announcement of the discovery of the Higgs boson, researchers have been working to fill in a gap in their measurements—they never yet saw the particle’s telltale decay into “matter” particles. This observation was considered an important indicator of the particle’s true identity.

Now scientists have succeeded in that observation, confirming that the particle whose discovery was announced at CERN on July 4th 2012, is indeed the long-sought-after Higgs boson.

In a nutshell, researchers determined that the boson whose existence was detected at CERN indeed decays into fermions—as predicted by the standard model of particle physics. Until now, the decay modes discovered at CERN have been of a Higgs particle giving rise to two high-energy photons, or a Higgs going into two Z bosons or two W bosons.

Making the Model

The standard model of particle physics is a view of all the particles and forces in the universe that explains the connections among them. Its underlying logic consists of deep mathematical symmetries that are believed to rule the interactions among elementary particles. The model is explained through quantum field theory—an amalgam of quantum mechanics and Einstein’s special theory of relativity. (If the general theory of relativity were to also be incorporated into this framework, it should lead to an understanding of quantum gravity.)

It is according to the standard model that the Higgs boson (which could be called the Higgs-Brout-Englert-Guralnik-Hagen-Kibble boson, for the other physicists whose work contributed to its discovery) endows particles with mass.

Many of the massive particles are, in fact, fermions, and so the Higgs is believed to couple to them. But this could not be proved as long as the Higgs was not found to decay—directly—into any of them.

Enter the Tau

In the new research work, just published in the journal Nature Physics, physicists fired protons at each other (as the Large Hadron Collider does) and scrutinized the collision results to see if they could find leptons (fermions that are similar to the electron, including the electron itself). In particular, they were looking for the heaviest lepton known, called the tau particle. The reason for this is that the more massive a particle is, the stronger its coupling to the Higgs. The tau is 3,500 times more massive than the electron (weighing in at about 1.8 GeV). And indeed researchers spotted tau leptons with a high degree of certainty, proving a decay of the Higgs boson into leptons.

The new findings are at a level of 3.8 sigma. This means, roughly speaking, that there is a 1 in 10,000 chance that the results are a false positive. The physicists are now waiting to confirm the result at the more exacting (and standard in particle physics) 5-sigma level, which would mean the probability described above would be roughly 1 in two million.

More work will be necessary, in order to both obtain stronger statistical proof of the new findings, and further verify other properties of the boson. But it looks like we are finally getting pretty close to certainty that the Higgs particle exists, and it agrees with the theory that has launched the massive search for it.

CATEGORIZED UNDER: Space & Physics, top posts
MORE ABOUT: higgs boson, physics
  • RAJ

    higgs boson is imaginary one– because- lots of things can produce 2 photons. like according to feynman’s diagram- 1 electon and 1 positron can produce = 2 photons ; then is the elecctron higgs boson now?

    • RAJ

      higgs boson is imaginary one– because- it is not directly observed- lots of things can produce 2 photons. like according to feynman’s diagram- 1 electon and 1 positron can produce = 2 photons ; then is the elecctron higgs boson now? so the higgs boson is one of the fake boson ever we have yet. no one can explain how does the mass of higgs boson formed ?how can higgs boson explain the gravity? there is no answer– thats why higgs boson is created in mind by the images created by two photons in many computer screens .( doubt every thing- find your own light- this is the dictum of science). so i doubted here on so called -discovery of higgs boson.

      • Dante Prudente

        Hummmm… why no clarification from Discover? Perhaps Raj is right. Science “ASS-U-MEs” that the Higgs Boson MUST exist. This can lead to a serious bias of interpretation on data. Could it be that scientists are gasping at straws, seeing things that just aren’t there? After all is this not really all about atheists satisfying their egos and some how proving (or deluding themselves) that God does not exist. Is not faith and theology simply the trusting of then theorizing on God? Science (and reason) is just another kind of religion. Plato knew that all too well.

        • steven page

          what an incredibly asinine comment. you negate the fact that science has one fundemental cause: to discover to truth. they do this by having different factions debating different topics, and different theories, which leads to fact through analyzing data and experiment. one great example of a debate at the LHC was over super symmetry and the multiverse theory. just like this, there is debate over the higgs. there are always opposing theories, ready to be tested and extrapolated, when something has been proven wrong. while many people are sure the higgs boson is real, it doesn’t mean that science is collectively unified and dead set on one theory. not by ANY means.

          and no, this is not about atheists prooving god doesn’t exist. it’s about understanding the underlying beauty of our universe, and our significance in it. what is biased is your overview and interpretation of how science WORKS. and what leads me to think that is your close minded view of theism and religion.

          first off, there is a large difference between “theory”, and “Scientific Theory”. scientific theory is something that can be used to predict or understand things in our universe, and can be proven absolute through repeated testing and observation. does this even apply to your definition of the word “theory”, when used in conjuction with God? I fail to see where God makes “theories” in the first place? he is absolute and omnipotent.

          moreover, there are plenty of places where physics and theology respects each other. moreover, there are plenty of times where religion has been forces to assimilate finding in scinece, because of it’s absolute certainty.

          and your idea that Science is a Religion? that can be interpreted differently depending on your point of view. Religion in it’s simplest meaning is a set of views on how life and the universe works.

          if you define it literally. so what? why must this have a negative connotation? this is exactly what it is!

          but lets be realistic here. the Religion defined by Theology is not based on rigorus scientific experiments. it’s based on loosley based logics, forged over centuries, without access to advanced technology. it’s based on benediction. it’s based on ritual observance of faith. it’s based on ethics. and morals.

          science is not these things. science cares only about facts.

          translation: while both are sets of beleifs, one is based on facts. while the other is based on faith. this is what sets them apart. and the only thing they have in common is root-word meaning.

          regardless, your view of science appears to be obscured due to a lack of understanding within regard to the process. and your opinion seems to be biases due to a misunderstanding within regard to religion.

          you should not generalize scientists. not all of them are atheists. not all of them have the same views. not all of them are reading out of the same book. their jobs are NOT just to prove theories right. but to also prove them wrong.

          even the general theory of relativity was debated down to the very last minute, with Albert Einstine eagarly awaiting his nobel prize to the last minute. and in the end, he was never awarded the nobel prize for this theory, but an earlier one.

  • Gray

    Hey Discover Magazine. How about you actually cover the news about Higgs Boson. I’m speaking specifically about how scientists very recently found that within a second of the Big Bang, the particles would have collapsed and according to the science, we shouldn’t exist.

    • http://blogs.discovermagazine.com Amir D Aczel

      Gray, you are right on! I proposed such a story to the editors a few hours ago. Stay tuned!…

    • Jason Moors

      This is complete ignorance you project. Science doesn’t make a claim that we should not exist, nor does it base claims off of anything but evidence. Furthermore, the best feature of science is that it constantly evolves it’s understanding of reality as more data is collected, not stick it’s head in the mud. Not only all that, you completely and utterly neglect the possibility of other particles and occurrences which may have taken place to lead to the current state of the universe. Do the world and science a favor and stay out of it and any discussions relating to it, as you choose to misunderstand it with presumption and lack of research on your part.

    • steven page

      not really “news”. things like this have been seen in science for as long as there has been theoritical physics. usually means there is a problem in the theory, or a problem in the math somewhere. either something needs to be refined, recalculated, or rethought all together. and this is also failing to mention that there is not ONE theory being debated here. there were a host of other theories ready to be put to the test if the higgs wasn’t found.

    • steven page

      moreover, the idea that “we dont even exist at all” as been circulating for years. Most cosmologists believe the universe contains exactly zero energy. if you consider the fact that energy has both negative and positive values, if you were to add them all up, the total energt in the universe would equal zero.

      if you couple this with the fact that matter has been found to act just like electrons do (have a wave function until an observer collapses it), it really does seem to point to the idea that NOTHING exists. figure that out! now the idea that “we shoulden’t exist” doesnt seem so weird when you figure we don’t really exist at all.

      but should that stop people from probing for the truth?

      i think not

  • Jason

    Something that I have found misleading or at least glossed over in a lot of articles like this is that the Higgs Field only gives *some* of the mass, in fact I think it is a small minority of mass. If I understand the physics correctly it is the strong interaction that supplies the lion’s share of the observable mass. Is my understanding correct Discover Magazine?

    • http://blogs.discovermagazine.com Amir D Aczel

      Jason, that’s a really tough question. The Higgs was proposed by 3 papers (hence the 6 names) in 1964. In 1967, Steven Weinberg wrote a landmark paper called “A model of leptons”–something like 2 pages only, but one of the greatest papers in the history of physics. In it–in addition to several other things–he made the first reference in history to what he called “The Higgs mechanism.” He used it to break a fourfold symmetry: photon-Z0-W+-W-. In the primeval universe (pre-Higgs action) these four BOSONS were all massless. When the Higgs interacted with them (they are called the electroweak field), it broke the symmetry, leaving the photon massless and GIVING MASS to the triple of “weak-interaction bosons”: Z0, W+, and W-. These three are now confined to act inside nuclei and are responsible for the weak force that control beta (a form of radioactivity) decay. Now, as Weinberg explained to me in 2009: If the Higgs exists (it was 3 years before the CERN discovery) we would know it gives mass to these three. “We suspect that it probably gives mass to other massive particles as well.” Now the Higgs has been found and we know for sure that the masses of WWZ is obtained from the Higgs. The great aspect of the new discovery (above) is that it makes it extremely likely–because the Higgs interacts with a “matter particle” (a lepton, here) that it also gives mass to all these massive ELEMENTARY particles. I highlight this word because I understand your question: The proton is much, much more massive than the sum of its three quarks. And so is the neutron. So what’s going on here? The answer is that probably all elementary particles get their mass from the Higgs. BUT: the difference between the massive proton (and neutron) and the sum of the (elementary) quarks’ masses is the KINETIC energy of motion of the quarks within the nucleon (proton, neutron)–and thus you could say that it is “caused” or at least controlled by the strong force–manifesting itself as mass. (This was explained, among others, also by an American Nobel physicist: Jerome Friedman.)

      • Jason

        Thank you for the excellent reply! I had never encountered this part of the science or line or reasoning before reading Sean Carroll’s excellent book on the Higgs discovery (and really just a great excuse for him to write about quantum field theory). Your remarks have helped solidify some of what he wrote, which I have been grappling with for the last couple of months since my reading.

  • Jonus Hk

    Im just trying to figure out how this is gonna feed that starving baby in Africa.

    • sbkw1983

      The real world applications are still decades away, however, without such fundamental scientific endeavors in the past, there would be no such thing as – for example – the internet, television, radio, etc. (among countless other modern comforts we take for granted).

    • q00lKat

      As a proud Christian conservative, I feel that once out of the womb, that baby is on its own.

      • steven page

        bet your glad you werent born into a country consumed with war, poverty, famine, and disease. whats there to be proud of in not helping somebody, when you are in a position to help? sounds cruel to be honest.

        and in what society does a baby fend for it self once out of the womb? i don’t think there is ANY society like that.

        it’s the community that raises a child, not just the parents. and what kind of community will a child bare, with not democratic process? no education system? no economy? no health care system?

        a dead baby.

    • steven page

      sbkw1983 hit the nail on it’s head: no scientific endeavor has ever been started with the thought “is this going to be good for the economy?” or “what about the starving children in Africa”?

      but guess what? because of things like this, we really ARE solving hunger in Africa.

      do you know what the percentage of money is that each country spends on basic scientific research?

      if you were to calculate how much goes into everything from defence to science: research like this would be but a raindrop in the pond.

      however, our standard of living is, in large measure, a result
      of scientific discovery and technological innovation. every person
      has a vested interest in the health of public science, and the use of
      scientific evidence to protect and sustain the values we hold.

      and to what sbkw1983 said… radio was never discovered through invention. it was discovered almost by accident, through experiment.

      quantum physics was almost entirely responsible for the semicondunctor.

      infact, thought experiment, theoretical science, and things of the like are entirely responsible for the world we have around us.

      no go take a look at poverty in Africa. its a fact that poverty is slowly being elimnated. slowly but surely. poverty is alot better TODAY, than it was in our recent past.

      and THIS is a result of globalization and technolgical innovation.

      and you have science to thank for that.

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