The Higgs boson | CERN The Higgs boson This content is archived on the CERN Document Server On 4 July 2012, the ATLAS and CMS experiments at CERN's Large Hadron Collider announced they had each observed a new particle in the mass region around 126 GeV. This particle is consistent with the Higgs boson predicted by the Standard Model. The Higgs boson, as proposed within the Standard Model , is the simplest manifestation of the Brout-Englert-Higgs mechanism . Other types of Higgs bosons are predicted by other theories that go beyond the Standard Model.

On 8 October 2013 the Nobel prize in physics was awarded jointly to François Englert and Peter Higgs "for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider." Particle 'Consistent' With Higgs Boson Discovered - Seeker Jul 4, 2012 05:40 AM ET Particle 'Consistent' With Higgs Boson Discovered A boson that resembles the Higgs has been detected by two Large Hadron Collider experiments. Previous Next The massive CMS detector in the LHC (CERN/LHC/CMS) The discovery of a particle consistent with the Higgs boson has been announced by physicists from the Large Hadron Collider’s CMS and ATLAS detectors. The discovery was detailed at a major conference to update the world on the continuing efforts by CERN scientists to find the last remaining piece of the Standard Model that underpins the foundations of our Universe.

The Higgs boson mediates the “Higgs field” that ultimately endows all matter with mass — finding the Higgs is therefore imperative for physicists to understand what gives the Universe substance. “We have observed a new boson.” – Joe Incandela, CMS lead physicist When reports first surfaced that Peter Higgs — one of the six physicists who, in the 1960s, developed the theory behind Higgs boson — had been invited to CERN for this morning’s announcement, the event became hard to ignore: something historic was about to happen. PHOTOS: When the World Went Higgs Boson Crazy And sure enough, at 9 a.m. in Geneva, Switzerland (3 a.m. EST), the news we had all been waiting for was spelled out by Joe Incandela, lead scientist of the CMS experiment: “We have observed a new boson.” This “new boson” revealed itself in the CMS data as a “bump” at 125 GeV/c2, a value that places it at over 130 times more massive than a proton.

After combining all the results gathered over many different channels in the CMS, the level of certainty — 4.9-sigma — came tantalizingly close to the “Gold Standard” (5-sigma) for subatomic particle discovery. This means there is a one-in-2 million chance of the result being a random fluctuation, or noise. For all intents and purposes, this is a discovery of a particle that acts very much like a Higgs boson. “This is very preliminary result, but it’s very strong,” added Incandela. ANALYSIS: Higgs Boson Hunt: ‘We’ve Discovered Something’ Following the CMS announcement, ATLAS’ Fabiola Gianotti said: “We observe in our data clear signs of a new particle, at the level of five sigma, in the mass region around 126 GeV.” A 5-sigma result represents a one-in-3.5 million chance of the result being noise. This is undeniable proof that a boson, with very Higgs-like qualities, has been discovered by the two detectors.

However, more work needs to be done to figure out if this is indeed a Higgs boson or some unexpected renegade particle that just acts like the Higgs (although the latter is highly unlikely). Also, if it is a Higgs boson, is it a part of a larger Higgs family of particles? In this high-stakes game of quantum mechanics, statistics and landmark particle discoveries, it can be hard to pronounce a definitive discovery of any subatomic particle, especially if it happens to be a particle that underpins the Universe’s very existence. The ATLAS and CMS detectors are located at strategic locations around the 17-mile (27-kilometer) circumference ring of superconducting electromagnets of the LHC. Both detectors are looking for, amongst a myriad of other things, evidence for the Higgs. And both, according to this announcement, have found that evidence to a very high degree of statistical certainty. During all the excitement of a round of LHC results announced in December 2011, physicists pointed to an “excess” of particles around the predicted energy range for one type of theoretical Higgs boson.

The energy range was 115 to 130 GeV/c2 and the statistical certainty was 2.4-sigma. 2.4-sigma means that there is a 98 percent chance that the signal is real and not caused by experimental error. HOWSTUFFWORKS: What is the Higgs boson? Interestingly, on Monday , physicists of the DZero and CDF experiments at the Fermilab’s now-retired Tevatron particle accelerator announced a 2.9-sigma “bump” around the 115 to 135 GeV/c2 energy range (that’s a 99.998 percent chance that the signal is real and not caused by experimental error). Not only are different detectors in the same particle accelerators capturing signals that relate to the theoretical energy of the Higgs, different detectors in different accelerators are suggesting the same thing! “I think we have it,” said CERN Director-General Rolf Heuer.

“We have discovered a particle that is consistent with a Higgs boson.” Higgs boson announcement: Cern scientists discover subatomic particle | Science | theguardian.com Higgs boson announcement: Cern scientists discover subatomic particle Scientists gather for a major announcement in Cern, home of the Large Hadron Collider What happens inside the Large Hadron Collider. Scientists at Cern, near Geneva, have this morning announced the likely discovery of the Higgs boson particle. Photograph: Cern 7.17am: Good morning all. Two teams of physicists at the Cern laboratory near Geneva are preparing today to announce their latest efforts to discover the Higgs boson . Participants take a rest early before the opening of the seminar. Photograph: Denis Balibouse/AFP/Getty Images The elusive "God particle" has become the most sought-after particle in modern science. Its discovery would be proof of an invisible energy field that fills the vacuum of space, and excitement in the scientific community is at fever pitch.

Peter Higgs, the Edinburgh University physicist who proposed the idea of the particle in 1964, is flying in to Geneva, as are two other men who published similar theories at around the same time: François Englert, professor emeritus at the Free University of Brussels (ULB) in Belgium, and Tom Kibble, professor emeritus at Imperial College London. There have been rumours, speculation, and, last night, even an apparent leak from the laboratory when a video announcing the discovery of a new particle was accidentally posted on its website. The Guardian's Ian Sample has flown to Geneva and I'll be live-blogging this potentially historic morning on this page. 7.38am: Now, two video links for your viewing pleasure. This one is to Cern's own live stream from where the scientific session is due to start at 9am local time (8am British time) - and subsequent press conference - will be held. And here is a video from the Guardian's own resident boffin, science correspondent Ian Sample. Heroically, he attempts to explain the Higgs boson by means of a tray from our canteen and some coloured ping pong balls.

British physicist Peter Higgs (right) arrives at the seminar. Photograph: Fabrice Coffrini/AFP/Getty Images 7.52am: Clapping for Peter Higgs, who has just arrived in the auditorium. Now, the anticipation mounts. 8.02am: And we're off. First up is Joe Incandela, the leader of the team using the CMS detector to search for new particles. He'll be followed by Fabiola Gianotti from the other team using the Atlas detector. He says the results are "very strong, very solid". 8.13am: As Incandela speaks, the brilliant Ian Sample is live-tweeting from Cern. I've been told that anyone who thinks they haven't found a new particle after this has lost touch with reality. #cern #lhc #higgs #ichep2012 — New Scientist (@newscientist) July 4, 2012 9.14am: "Both experiments observe a new particle in the mass region around 125-126 GeV," confirms a press release from Cern.

Gianotti- who is still speaking- is quoted in this release as saying: We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage, but a little more time is needed to prepare these results for publication. Incandola, from CMS, adds: The results are preliminary but the 5 sigma signal at around 125 GeV we're seeing is dramatic. This is indeed a new particle. We know it must be a boson and it's the heaviest boson ever found. The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks. And Sergio Bertolucci, research director of CERN, says: It's hard not to get excited by these results. We stated last year that in 2012 we would either find a new Higgs-like particle or exclude the existence of the Standard Model Higgs.

With all the necessary caution, it looks to me that we are at a branching point: the observation of this new particle indicates the path for the future towards a more detailed understanding of what we're seeing in the data. The results presented today are labelled preliminary, the statement adds. They are based on data collected in 2011 and 2012, with the 2012 data still under analysis. Publication of the analyses shown today is expected around the end of July. A more complete picture of today's observations will emerge later this year after the LHC provides the experiments with more data. The next step will be to determine the precise nature of the particle and its significance for our understanding of the universe. Are its properties as expected for the long-sought Higgs boson, the final missing ingredient in the Standard Model of particle physics? Or is it something more exotic? The Standard Model describes the fundamental particles from which we, and every visible thing in the universe, are made, and the forces acting between them. All the matter that we can see, however, appears to be no more than about 4% of the total.

A more exotic version of the Higgs particle could be a bridge to understanding the 96% of the universe that remains obscure. Positive identification of the new particle's characteristics will take considerable time and data. But whatever form the Higgs particle takes, our knowledge of the fundamental structure of matter is about to take a major step forward. 9.21am: First reaction from Peter Higgs has just landed in my inbox. According to a statement sent by Edinburgh University, the physicist says he is "astounded" at the speed with which the results have emerged and is preparing to celebrate. Scientists at CERN are to be congratulated on today's results, which are a great achievement for the Large Hadron Collider and other experiments leading up to this. I am astounded at the amazing speed with which these results have emerged. They are a testament to the expertise of the researchers and the elaborate technologies in place. I never expected this to happen in my lifetime and shall be asking my family to put some champagne in the fridge. Participants applaud after the presentation of the Atlas experiments. Photograph: Denis Balibouse/AP 9.23am: Gianotti is still presenting Atlas's results but the reaction is already pouring in.

Here's are the first few paragraphs from Ian Sample's first take on today's momentous announcement. There comes a time in a scientist's life when the weight of evidence can no longer be ignored. That moment came today for physicists at Cern , home of the Large Hadron Collider near Geneva, who announced overwhelming evidence for the obscure but profoundly important Higgs boson, the particle that sparked the greatest hunt in modern science. In presentations given to a packed auditorium at the laboratory on Wednesday morning, and webcast around the world, the leaders of two research teams, who worked independently of each other, said they had spotted a new particle amid the microscopic flashes of primordial fire created inside the world's most powerful atom smasher. Cern stopped short of claiming official discovery of the Higgs boson, even as many physicists conceded the evidence was now so compelling they had surely found the missing particle. Formal confirmation of the discovery is expected within months, though it could take several years for scientists to work out whether they have found the simplest kind of Higgs particle that theories predict, or part of a more complex picture: for example, one of a larger family of Higgs bosons.

The discovery of more than one kind of Higgs particle would open the door to an entirely new realm of physics. 9.29am: "#CERN" is trending worldwide. As is #Higgs, and #GodParticle (sorry), and ATLAS. No #Higgsteria yet though, despite a valiant effort by social media types. 9.32am: Today's discovery is "unbelievably exciting", according to Harvard physicist Lisa Randall. She told the Guardian: I really didn't expect this. They got enough data and improved analysis to the point where we know about a new particle months before I expected (based on asking lots of people)! It is unbelievably exciting. Tommaso Dorigo , a scientist on the CMS experimental team at Cern, had this evaluation for Ian over in Geneva: Is it a Higgs boson or not? Well, it has been found using techniques tuned for the Standard Model Higgs. A different object might have stepped in, but it is quite unlikely in my humble opinion. A representation of traces of a proton-proton collision in the search for the Higgs boson, released by Cern.

Photograph: AFP/Getty Images 9.35am: Cheers and applause for Gianotti now. ATLAS - round of applause + cheers. 5 sigma discovery at 126.5 GeV It's like zoologists trying to determine if they've discovered a new species of butterfly by looking at a meadow through binoculars. From 16 miles away. Shiv Malik Our very own Shiv Malik has also put his scientist's hat on to try to explain One talking point is how reliable the results are. This is based on how certain physicists are about the data they have. The way this is normally measured is through standard deviation i.e. the 1-5 sigma that we've been hearing about. This handy explainer graphically shows what deviation is on a usual distribution graph or a bell curve, where most results are based around the middle but there are also some extreme results at either end. Something like plotting height amongst a big population of 35 year old males would give you a bell curve graph like this. Tall and short at either end but most people are say, 5 Ft 8". Five sigma from the standard deviation therefore means many steps away from the norm.

In terms of height it would be say, adults males who are either 2ft or 7ft tall i.e. very unusual. But now reverse engineer the exercise. Imagine you are looking at 7ft people and you want to know how likely it is that this is a strange result from the middle or the norm. How would you work this out? How would you come up with a number to represent this? Well, looking at the data, plotting the graph, you could say that 7ft adult males represent 5 sigma deviation from the norm, so you are pretty sure that this is an odd or unusual result and therefore worth being (statistically speaking) interested about. This is what those at CERN have been saying today. 11.00am: As the journalists in Geneva continue to beg the Cern guys for replies they can understand, here at the Guardian we are begging you to help us explain the Higgs boson. My colleagues write: Can you help us break it down into even simpler terms? If you're a scientist, a teacher or a physics fan with a knack for explaining big ideas and small particles, we're imploring you to help.

• How would you explain Higgs boson to a 7-year-old? • What analogy best explains what's happening at Cern? • Can it be described in 200 words? 11.09am: A bold Reuters journalist just asked them to provide their own metaphors for the Higgs boson. Alas. "The podium is metaphorless," replied Heuer. British physicist Peter Higgs (right) speaks with Belgium physicist Francois Englert. Photograph: Fabrice Coffrini/AFP/Getty Images 11.18am: Ok, that's that. The press conference is over. Throughout, Peter Higgs refused to make any comment other than to praise the achievement and to say he was making no further comment. He obviously didn't want to hog the limelight, which will only endear him further to his new legion of Twitter fans. 11.25am: On a lighter note, here's a storify of Twitter jokes about the Higgs boson as collated by Hannah Waldram. Sure there are plenty more to come, so tweet your best to @guardian on #higgsjokes.

11.34am: You can now read Ian Sample's excellent take on this morning's announcement at length here. And, for those of who still a little in the dark, check out this fun explainer video by PHD Comics on Vimeo. Thanks to Koos Fuite below the line for the spot. 11.55am: My colleagues Hannah and Laura have been collating some of the lovely explanations coming in in response to our plea to explain the Higgs boson in a way a 7-year-old child would understand. My favourite- and certainly the most inventive- is egorulz's effort below the line. Once upon a time in a far away land, there were two rival families: Fermions and Bosons. Fermions were famous for their peculiar half spin dance. Electrons, protons and quarks were all Fermions. The Bosons however were into full spinning though and despised half spin. Photons and Gluons were Bosons. It was rumored that Bosons had a long lost elder brother called Higgs Boson who had been missing for a long long time. One day a wise old man came to the land of the feuding families.

He told them they should stop quaerlling over half spin and full spin, since they all used to be the same, and that they all used to be massless. The old man said that, in the beginning of time when the universe was created, everyone was born the same, but then they were immersed in a mysterious field called the higgs field making each of them different except for Photons who remained the same. He said this mysterious field was made up of the Higgs Boson - the long lost Boson brother. The families ofcourse refused to believe all this hogwash, and so the old man set about trying to prove his story and bring the Higgs Boson out of his hiding place. To do this he asked for help from the scientists at CERN. The family feud is coming to an end, at last. 12.03pm: The science community seems agreed: this is a big moment. But many, like Heuer, are cautioning that this could be just the beginning. Dr Roberto Trotta, Lecturer in Cosmology at Imperial College London, has this to say, according to the Science Media Centre.

This could be just the first step towards uncovering a completely new layer of reality - the Higgs might lead to the discovery of supersymmetry: the notion that for every known particle there exist a super-particle with a much larger mass. And if supersymmetry is real, then we are on our way to finally crack the mystery of the dark matter in the Universe. Dark matter might be 'the last Highlander' of all supersymmetric particles, the only surviving 'sparticle' from the Big Bang. And we might be on the verge of hunting it down at the LHC. Professor John Womersley, STFC Chief Executive, said: Obviously having found a new particle, there is still much, much more to do at the LHC – we need to confirm that this new particle is the reason some particles have tangible mass while others are insubstantial – as proposed by Peter Higgs and other scientists, who predicted that a previously unknown particle must exist for our current understanding of the Universe to work. And, for Professor Valentin Khoze, Director of Durham University's Institute for Particle Physics Phenomenology (IPPP), this discovery is just opening the door to others that could be even more exciting.

The second part of the story about the Higgs particle is even more exciting as it provides us with a window to new physics - a tool for the exploration of the truly unknown. The next stage will be a detailed and careful study of its properties. Successful completion of this second stage will bring us closer to uncovering new physics, explaining dark matter and other mysteries of the Universe. 12.09pm: Ian Sample has this thought for us: Stephen Hawking bet Gordy Kane (UMICH) $100 that the Higgs would never be found at Cern. Wonder if he's conceded defeat? #Higgs #ichep2012 Video: Cern scientists on Higgs boson discovery - Telegraph Large Hadron Collider Cern scientists on Higgs boson discovery Scientists have discovered a subatomic particle that is consistent with the Higgs boson particle that gives matter mass, Cern, the European Organisation for Nuclear Research, announced today.

8:31AM BST 04 Jul 2012 Rolf Heuer, director of the European Center for Nuclear Research, or Cern, said "we have a discovery" of a new subatomic particle, a boson, that is "consistent with a Higgs boson." He added: "I think we have it." He spoke after two independent teams at Cern said they have both "observed" a new particle. Finding the Higgs is vital to the Standard Model, the theory that describes the web of particles, forces and interactions that make up the universe. Without the Higgs boson to give matter mass and weight, there could be no Standard Model universe. If it was proved not to exist, scientists would have to tear up the theory and go back to the drawing board. Today's announcement came at a packed seminar at the Geneva headquarters of Cern, the European Organisation for Nuclear Research, where a tense audience heard the latest progress report from the LHC.

Related Content Higgs boson-like particle discovery claimed at LHC - BBC News Higgs boson-like particle discovery claimed at LHC By Paul Rincon Science editor, BBC News website, Geneva 4 July 2012 From the section Science & Environment comments Close share panel Media captionThe moment when Cern director Rolf Heuer confirmed the Higgs results Cern scientists reporting from the Large Hadron Collider (LHC) have claimed the discovery of a new particle consistent with the Higgs boson. The particle has been the subject of a 45-year hunt to explain how matter attains its mass. Both of the Higgs boson-hunting experiments at the LHC (Atlas and CMS) see a level of certainty in their data worthy of a "discovery". More work will be needed to be certain that what they see is a Higgs, however. Media captionProf Stephen Hawking tells the BBC's Pallab Ghosh the discovery has cost him $100 The results announced at Cern (European Organization for Nuclear Research) , home of the LHC in Geneva, were met with loud applause and cheering.

Prof Peter Higgs, after whom the particle is named, wiped a tear from his eye as the teams finished their presentations in the Cern auditorium. "I would like to add my congratulations to everyone involved in this achievement," he added later. "It's really an incredible thing that it's happened in my lifetime." Prof Stephen Hawking joined in with an opinion on a topic often discussed in hushed tones. "This is an important result and should earn Peter Higgs the Nobel Prize," he told BBC News. "But it is a pity in a way because the great advances in physics have come from experiments that gave results we didn't expect." 'Dramatic' The CMS experiment team claimed they had seen a "bump" in their data corresponding to a particle weighing in at 125.3 gigaelectronvolts (GeV) - about 133 times heavier than the protons that lie at the heart of every atom. Media captionThe BBC's George Alagiah explains the Higgs boson They claimed that by combining two data sets, they had attained a confidence level just at the "five-sigma" point - about a one-in-3.5 million chance that the signal they see would appear if there were no Higgs particle.

However, a full combination of the CMS data brings that number just back to 4.9 sigma - a one-in-two million chance. Prof Joe Incandela, spokesman for CMS, was unequivocal: "The results are preliminary but the five-sigma signal at around 125 GeV we're seeing is dramatic. This is indeed a new particle," he told the Geneva meeting. The Atlas experiment results were even more promising, at a slightly higher mass: "We observe in our data clear signs of a new particle, at the level of five sigma, in the mass region around 126 GeV," said Dr Fabiola Gianotti, spokeswoman for the Atlas experiment at the LHC. Image caption Peter Higgs joined three of the six theoreticians who first predicted the Higgs at the conference Prof Rolf Heuer, director-general of Cern, commented: "As a layman I would now say I think we have it." "We have a discovery - we have observed a new particle consistent with a Higgs boson. But which one? That remains open.

"It is a historic milestone but it is only the beginning." Commenting on the emotions of the scientists involved in the discovery, Prof Incandela said: "It didn't really hit me emotionally until today because we have to be so focussed… but I'm super-proud." Dr Gianotti echoed Prof Incandela's thoughts, adding: "The last few days have been extremely intense, full of work, lots of emotions." A confirmation that this is the Higgs boson would be one of the biggest scientific discoveries of the century; the hunt for the Higgs has been compared by some physicists to the Apollo programme that reached the Moon in the 1960s.

Statistics of a 'discovery' Particle physics has an accepted definition for a "discovery": a five-sigma level of certainty The number of standard deviations, or sigmas, is a measure of how unlikely it is that an experimental result is simply down to chance, in the absence of a real effect Similarly, tossing a coin and getting a number of heads in a row may just be chance, rather than a sign of a "loaded" coin The "three sigma" level represents about the same likelihood of tossing nine heads in a row Five sigma, on the other hand, would correspond to tossing more than 21 in a row Unlikely results are more probable when several experiments are carried out at once - equivalent to several people flipping coins at the same time With independent confirmation by other experiments, five-sigma findings become accepted discoveries Scientists would then have to assess whether the particle they see behaves like the version of the Higgs particle predicted by the Standard Model, the current best theory to explain how the Universe works. However, it might also be something more exotic. All the matter we can see appears to comprise just 4% of the Universe, the rest being made up by mysterious dark matter and dark energy.

A more exotic version of the Higgs could be a bridge to understanding the 96% of the Universe that remains obscure. Scientists will have to look at how the Higgs decays - or transforms - into other, more stable particles after being produced in collisions at the LHC. Dr Pippa Wells, a member of the Atlas experiment, said that several of the decay paths already showed deviations from what one would expect of the Standard Model Higgs. For example, a decay path where the Higgs transforms into two photon particles was "a bit on the high side", she explained. These could get back into line as more statistics are added, but on the other hand, they may not. "We're reaching into the fabric of the Universe at a level we've never done before," said Prof Incandela. "We're on the frontier now, on the edge of a new exploration.

This could be the only part of the story that's left, or we could open a whole new realm of discovery." The Standard Model and the Higgs boson • The Standard Model is the simplest set of ingredients - elementary particles - needed to make up the world we see in the heavens and in the laboratory • Quarks combine together to make, for example, the proton and neutron - which make up the nuclei of atoms today - though more exotic combinations were around in the Universe's early days • Leptons come in charged and uncharged versions; electrons - the most familiar charged lepton - together with quarks make up all the matter we can see; the uncharged leptons are neutrinos, which rarely interact with matter • The "force carriers" are particles whose movements are observed as familiar forces such as those behind electricity and light (electromagnetism) and radioactive decay (the weak nuclear force) • The Higgs boson came about because although the Standard Model holds together neatly, nothing requires the particles to have mass; for a fuller theory, the Higgs - or something else - must fill in that gap Paul.Rincon-INTERNET@bbc.co.uk and follow me on Twitter Google+ Sponsor Message <a href="" target="_top"><img

 style="border:0px;" src="" alt="i" width="300" height="250"/></a> Finally, physics’s zoo of subatomic particles is full.

Scientists have almost certainly snared the Higgs boson, the last particle waiting to be roped into the fold. Decades after it was proposed, the Higgs emerged in the shards of particle collisions at the world’s most powerful accelerator, the Large Hadron Collider at the CERN laboratory near Geneva. Physicists announced the discovery on July 4 during a seminar at the lab. “We have now found the last missing cornerstone of the standard model,” said Rolf-Dieter Heuer, CERN’s director-general. “It’s the beginning of a long journey to investigate all the properties of this interesting particle.” The particle’s mass is around 125 billion electron volts, or about 133 times the mass of a proton. CERN captured the Higgs in two huge experiments, each of which independently reached the gold-standard statistical level for confirming the particle’s discovery. One of the theorists who first proposed the particle nearly five decades ago joined in the all-around congratulations. “It really is an incredible thing that it’s happened in my lifetime,” said Peter Higgs of the University of Edinburgh.

In one respect, finding the Higgs simply confirms the standard model, physicists’ framework for understanding the particles that make up the universe and the forces that govern them. But the discovery also opens new areas to explore, including alternate versions of the standard model that could explain some of the biggest unanswered questions about the cosmos. The Higgs traces back to 1964, when several physicists independently dreamed up the idea of an energy field that would have permeated the early universe (and persisted to the present). “In all honesty we were trying to solve a more modest problem,” said theorist Carl Hagen of the University of Rochester in New York. In certain theoretical calculations, particles with zero mass kept inconveniently popping up: In trying to get rid of those particles, Higgs, Hagen and others realized that once the universe cooled enough from its initial Big Bang, this energy field would have had to emerge. Like a puddle of molasses, the field resists the motion of particles moving through it. Such resistance to motion, or inertia, is the defining quality of mass. Subatomic particles therefore acquire differing amounts of mass depending on how strongly they interact with the energy field.

Known as the Higgs field, its existence also required a new particle — the Higgs boson. (Bosons are a class of fundamental particles defined by their quantum properties.) Finding the Higgs was a major goal of the Superconducting Super Collider, an atom-smasher that was being built beneath Waxahachie, Texas, when the U.S. Congress canceled it under budget pressures in 1993. The Fermi National Accelerator Laboratory, in Batavia, Ill., also chased the Higgs until shutting down its biggest machine last year. Today, CERN scientists hunt the Higgs by smashing two beams of protons together at the $10 billion LHC. Out of a trillion proton-proton collisions, perhaps one will create a Higgs particle, which then decays almost instantaneously into other particles. Sensitive detectors placed at the sites of these smashups look for signatures of several ways the Higgs might have decayed. “It’s not a needle in a haystack — it’s much worse than a needle in a haystack,” said Joe Lykken, a theoretical physicist at Fermilab.

If each of the LHC's 500 trillion collisions were represented by a grain of sand, they would fill an Olympic-sized swimming pool, said Joe Incandela, a physicist at the University of California, Santa Barbara and a spokesman for one LHC experiment. Yet the grains from the signals of interest — the possible Higgses — would cover only the tip of your finger. Both experiments looked at multiple ways the Higgs could decay, such as into two photons or into two Z particles. One of the LHC’s two main detectors, the CMS experiment, found signs of a particle with a mass of 125.3 billion electron volts, plus or minus 0.6 billion electron volts, Incandela said. The statistical strength of a signal is measured by a quantity called sigma: A five-sigma result, considered the standard to claim a discovery, means there is a 1-in-3.5 million chance that a statistical fluke could have created a signal of that magnitude or greater. In three of five decay paths studied, CMS found the Higgs with a statistical significance of 5.1 sigma.

Adding in the other two channels, which have relatively little data, lowered that to 4.9 sigma — but the results are still consistent with a Higgs being there, said physicist Elizabeth Simmons of Michigan State University. The competing ATLAS experiment spotted a new particle with a mass of 126.5 billion electron volts, with a statistical uncertainty at a 5.0 sigma level when combining the decay paths it examined. Independent physicist Philip Gibbs combined data from both ATLAS and CMS, using only the decay in which the Higgs produces two photons, to come up with an unofficial six-sigma signal. The Higgs masses found by both experiments are consistent with one another given the uncertainty ranges in each measurement, said ATLAS spokeswoman Fabiola Gianotti (though she did not give a numerical error range for her experiment). Both teams will also present their work this week at the International Conference on High-Energy Physics in Melbourne, Australia. “It’s a great day for particle physics and it’s really a profound discovery about how nature works,” said Pier Oddone, director of Fermilab.

Back Story How the Large Hadron Collider works Buried up to 175 meters deep beneath the French-Swiss countryside, CERN’s premier particle accelerator hurls two beams of protons headlong into one another (arrows show paths). When they collide, the enormous energies generate other particles — including, presumably, the Higgs — that flash into existence, and then decay almost immediately. Giant detectors including the Compact Muon Solenoid (CMS) and A Toroidal LHC Apparatus (ATLAS) analyze the particle debris to determine what happened during the smashups. Image: © 2006 CERN CERN won the transatlantic race to find the Higgs after Fermilab’s proton-antiproton accelerator shut down last September. On July 2, in their final analysis, Fermilab physicists reported that their data could narrow the Higgs mass range only to between 115 billion and 135 billion electron volts, with a statistical significance of 2.9 sigma ( SN Online: 7/2/12 ).

Since April the LHC has been colliding beams at energies of 8 trillion electron volts — 4 trillion electron volts in each beam — at four times the energy of Fermilab’s machine. Lab officials have decided to extend the LHC’s current run by up to three months to gather as much data as possible before it shuts down for two years for a major upgrade to 14 trillion electron volts. Now that the Higgs has almost certainly been found, scientists are looking forward to learning more about it. So far, the particle seen in the experiments looks like the Higgs as predicted by the standard model, Heuer said, but slight differences could still exist. He compared the task to trying to determine from afar if a person approaching is your best friend or your best friend’s twin. Only when the person gets close enough can you determine which one it is. LHC measurements should soon reveal whether the particle’s properties match those predicted by the standard model, or whether new physics might be at work. “Confirmation of theory is satisfying, but it would be more eventful if there were significant disagreements and controversies to resolve,” said Frank Taylor, an MIT physicist who works on the ATLAS collaboration.

One well-loved extension of the standard model is a theory known as supersymmetry, which holds that all known particles have a heavy supersymmetric partner as yet unseen. The concept opens up all sorts of areas to explore. Some versions of supersymmetry, for instance, predict that at least five kinds of Higgs boson should exist, although only the lightest would be detectable at the LHC. Other supersymmetric particles may account for dark matter, the mysterious stuff that makes up most of the matter in the universe but which scientists have yet to identify. If supersymmetry is right, the LHC has a shot at detecting many of these new particles as it continues its Higgs-refining quest. “It’s the path to answer these other questions,” said Gordon Kane, a theoretical physicist at the University of Michigan whose work has predicted a Higgs in the mass range found. Fermilab’s Rob Roser said far more is yet to come from the LHC.

“They’re in a new regime of energy and statistical precision, and this may not be the only surprise we have this year from them.” Further Reading Penn plays role in Large Hadron Collider’s discovery of new particle | Penn Current Penn plays role in Large Hadron Collider’s discovery of new particle Penn plays role in Large Hadron Collider’s discovery of new particle Text by Evan Lerner Views of the Large Hadron Collider tunnel sector 3-4. Photo by Maximilien Brice An example of simulated data modeled for the CMS particle detector on the Large Hadron Collider at CERN. Photo by Lucas Taylor On July 4, the European Organization for Nuclear Research, CERN, announced the discovery of a particle thought to be the elusive Higgs boson, nicknamed the “God particle,” responsible for imbuing the universe with mass. The discovery was made possible by CERN’S Large Hadron Collider (LHC) in Switzerland, the $10 billion particle accelerator built to aid researchers in their quest to answer several fundamental questions of physics. Proving the existence of the Higgs boson was its most public goal, doggedly pursued by a collaboration of thousands of physicists from around the world.

“It couldn’t be more exciting,” says Brig Williams , professor of physics in Penn’s School of Arts and Sciences . “The machine has been running extremely well. We've already taken more data since April than we had all of last year.” Williams and fellow Penn physics professors Joseph Kroll , Eliot Lipelles , and Evelyn Thompson , along with their students, have played a large role in the design and construction of ATLAS, one of the two main particle detectors at the LHC. The LHC works by accelerating protons in opposite directions around a 17-mile-long circular track. When the beams are crossed inside the detectors, the protons collide in a huge explosion of energy that can create new particles. Only a machine as powerful as the LHC is thought to be able to create a particle as energetic as the Higgs boson. The problem inherent in studying this particle is that as soon as a Higgs is created, it immediately breaks apart into different particles that fly off in different directions. Penn’s chief contributions to ATLAS is the development of the electronics that help capture the proton collision outcomes in the ATLAS’ Inner Detector, and the creation of a process that helps researchers record only the most noteworthy of the millions of collisions that occur every second.

Following a collision, researchers trace the energy and trajectory of the shrapnel of the shattered particle as it passes through the detectors. This allows them to work backwards, piecing together the size of the original particle. One Penn team has been working at observing a process that would turn a Higgs particle into two photons, while another Penn team is looking at more exotic particles known as “W’ bosons. There are many other phenomena in particle physics that could produce the patterns associated with the Higgs, Williams says. Therefore scientists must collect mountains of evidence that all indicate the Higgs has one particular mass. CERN announced last December that researchers found hints of the Higgs between 125 and 126 gigaelectron volts (GeV), but more data was needed to declare with confidence the discovery of the Higgs. The July 4 announcement places a “5 sigma” likelihood of the Higgs particle being between 125 and 126 GeV. That is a mathematical way of saying that the odds of the discovery being a coincidence are 1 in 1.7 million.

“The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage,” says ATLAS experiment spokesperson Fabiola Gianotti, “but a little more time is needed to prepare these results for publication.” “There is a tradition in particle physics not to make a formal claim of something until you’ve submitted the paper,” says Williams. “We expect to do that at the end of July.” Views of the Large Hadron Collider tunnel sector 3-4. Photo by Maximilien Brice Originally published on LHC Smashes Particle Collision Record - Seeker May 24, 2011 03:00 AM ET LHC Smashes Particle Collision Record The Large Hadron Collider smashed the particle collision record. Learn more about the Large Hadron Collider smashing the particle collision record. CERN/LHC CERN's Large Hadron Collider (LHC) is housed in a 27-kilometre (16.9-mile) ring-shaped tunnel 100 metres (325 feet) below ground, straddling the French-Swiss border.

CERN/LHC THE GIST — A month ago, the Large Hadron Collider (LHC) was colliding particles at a rate of 10 million collisions per second. — At a conference in Paris, it was announced that the LHC is now running at 100 million collisions per second. The world's biggest particle collider set a new record early Monday, a feat that should accelerate the quest to pinpoint the elusive particle known as the Higgs Boson, a senior physicist said. "Last night, a symbolic frontier was crossed," said Michel Spiro, president of the board of the European Organization for Nuclear Research (CERN), explaining that the rate of sub-atomic smashups in its vast machine had multiplied 10-fold in the space of a month. CERN's Large Hadron Collider (LHC) is housed in a 27-kilometer (16.9-mile) ring-shaped tunnel 100 meters (325 feet) below ground, straddling the French-Swiss border. It is designed to accelerate beams of protons to nearly the speed of light in contra-rotating directions.

Then, using magnets, the beams are then directed into labs where some of the protons collide while others escape. Detectors record the seething sub-atomic debris, hoping to find traces of particles that can strengthen fundamental understanding of physics. A month ago, the LHC set a record of 10 million collisions per second. "This is now 100 million collisions per second," Spiro said at a conference in Paris on the "infinitely small and the infinitely big." Among the puzzles that physicists are seeking to answer is the existence of the Higgs, which has been dubbed "the God particle" for being mysterious yet ubiquitous. If found, it would explain the nature of mass, filling a major piece of the theoretical construct of physics known as the Standard Model. In London last week, CERN physicists said they believed that by the end of 2012 they could determine once and for all whether the Higgs existed or not. Spiro said that this search would certainly be helped by the stepped-up pace of collision, which is the equivalent to sifting more earth in search of nuggets of gold.

"If we're lucky, and it (the Higgs) is in the right zone for expected mass, we may be able to find it this summer," he said. "On the other hand, ruling it out will take us to the end of next year." To provide a confirmation would require notching up "at least 15" detections, he said. The first proton collisions at the LHC occurred on September 10, 2008. The smasher then had to endure a 14-month shutdown to fix technical problems. It had been due to shut down in early 2012 for work enabling it to crank up to full power. But a decision was made several weeks ago to delay closure for a year to help the Higgs hunt. MUST WATCH

Question: The effective discovery of what particle was announced by CERN at the Large Hadron Collider in 2012?
Answer: Higgs boson