The Higgs particle - what it is and what it does By Chris Wickham Wed Jul 4, 2012 4:54am IST Scientists at the CERN research centre near Geneva, Switzerland, will on Wednesday unveil the latest results in their search for the Higgs boson, a subatomic particle believed to be key to the formation of stars, planets and eventually life after the Big Bang 13.7 billion years ago. WHAT IS THE HIGGS BOSON? The Higgs is the last missing piece of the Standard Model, the theory that describes the basic building blocks of the universe. The other 11 particles predicted by the model have been found and finding the Higgs would validate the model. Ruling it out or finding something more exotic would force a rethink on how the universe is put together. Scientists believe that in the first billionth of a second after the Big Bang, the universe was a gigantic soup of particles racing around at the speed of light without any mass to speak of. It was through their interaction with the Higgs field that they gained mass and eventually formed the universe. The Higgs field is a theoretical and invisible energy field that pervades the whole cosmos. Some particles, like the photons that make up light, are not affected by it and therefore have no mass. Others are not so lucky and find it drags on them as porridge drags on a spoon. Picture George Clooney (the particle) walking down a street with a gaggle of photographers (the Higgs field) clustered around him. An average guy on the same street (a photon) gets no attention from the paparazzi and gets on with his day. The Higgs particle is the signature of the field - an eyelash of one of the photographers. The particle is theoretical, first posited in 1964 by six physicists, including Briton Peter Higgs. The search for it only began in earnest in the 1980s, first in Fermilabs now mothballed Tevatron particle collider near Chicago and later in a similar machine at CERN, but most intensively since 2010 with the start-up of the European centres Large Hadron Collider. WHAT IS THE STANDARD MODEL? The Standard Model is to physics what the theory of evolution is to biology. It is the best explanation physicists have of how the building blocks of the universe are put together. It describes 12 fundamental particles, governed by four basic forces. But the universe is a big place and the Standard Model only explains a small part of it. Scientists have spotted a gap between what we can see and what must be out there. That gap must be filled by something we dont fully understand, which they have dubbed dark matter. Galaxies are also hurtling away from each other faster than the forces we know about suggest they should. This gap is filled by dark energy. This poorly understood pair are believed to make up a whopping 96 percent of the mass and energy of the cosmos. Confirming the Standard Model, or perhaps modifying it, would be a step towards the holy grail of physics - a theory of everything that encompasses dark matter, dark energy and the force of gravity, which the Standard Model also does not explain. It could also shed light on even more esoteric ideas, such as the possibility of parallel universes. CERN spokesman James Gillies has said that just as Albert Einsteins theories enveloped and built on the work of Isaac Newton, the work being done by the thousands of physicists at CERN has the potential to do the same to Einsteins work. WHAT IS THE LARGE HADRON COLLIDER? The Large Hadron Collider is the worlds biggest and most powerful particle accelerator, a 27-km (17-mile) looped pipe that sits in a tunnel 100 metres underground on the Swiss/French border. It cost 3 billion euros to build. Two beams of protons are fired in opposite directions around it before smashing into each other to create many millions of particle collisions every second in a recreation of the conditions a fraction of a second after the Big Bang, when the Higgs field is believed to have switched on. The vast amount of data produced is examined by banks of computers. Of all the trillions of collisions, very few are just right for revealing the Higgs particle. That makes the hunt for the Higgs slow, and progress incremental. WHAT IS THE THRESHOLD FOR PROOF? To claim a discovery, scientists have set themselves a target for certainty that they call 5 sigma. This means that there is a probability of less than one in a million that their conclusions from the data harvested from the particle accelerator are the result of a statistical fluke. The two teams hunting for the Higgs at CERN, called Atlas and CMS, now have twice the amount of data that allowed them to claim tantalising glimpses of the Higgs at the end of last year and this could push their results beyond that threshold. (Editing by Kevin Liffey) https://facebook/photo.php?fbid=3467019915594&set=a.3445697342543.40414787.1273936657&type=1 in.reuters/article/2012/07/03/science-higgs-explanation-cern-idINDEE8620IJ20120703 Heres how the famous Higgs particle gives things mass Forget equations, physicists tend to explain process in terms of sports and syrup CERN / CMS Collaboration A computer graphic shows a typical Higgs boson candidate event, including two high-energy photons whose energy (depicted by red towers) is measured in the Compact Muon Solenoids electromagnetic calorimeter. The yellow lines are the measured tracks of other particles produced in the collision. The pale blue volume represents the CMS crystal calorimeter barrel. By Natalie Wolchover 7/3/2012 2:18:56 PM ET The infamous Higgs particle has a weighty task: It grants all the other elementary particles their mass. Without it, they — we — would zip around frantically at the speed of light, too foot-loose to form atoms. But how does the Higgs do it? In lieu of equations, physicists tend to explain the process in terms of sports and syrup. First, each of the elementary particles acquires its unique set of attributes by interacting with invisible entities called fields. Like football fields, these are large stages upon which individuals (be they electrons or running backs) dash this way and that, and occasionally bash together. But unlike football fields, the fields of physics are three-dimensional, and extend infinitely in all directions. One such field is the electromagnetic (EM) field — the kind you can feel near the poles of a red and silver bar magnet, but which actually exists everywhere all the time. Each particle interacts with the EM field in a way that depends on its electric charge. For example, electrons, whose charge is -1, tend to move through the field toward the positive ends of bar magnets, and to clump together with positively charged protons. Like a sports field with its corresponding ball, each field of physics has a corresponding particle. The EM field, for example, is associated with the photon, or particle of light. This correspondence plays out in two ways: First, when the EM field is excited, meaning its energy is flared up in a certain spot, that flare-up is, itself, a photon. Secondly, when particles interact with the EM field (for example, when they are drawn toward the oppositely charged end of a magnet), they experience the field by absorbing and emitting a constant stream of virtual photons — photons that momentarily pop in and out of existence just for the purpose of mediating the particle-field interaction. There also exists a Higgs field. It gives particles mass. [ How Do You Weigh an Atom? ] Advertise | AdChoices Except for massless photons and gluons, all elementary particles get their masses from their interactions with the (Higgs) field, kind of like being slowed down by passing through a thick syrup, explained James Overduin, a physicist at Towson University in Maryland. Some particles have a harder time trudging through the syrupy Higgs field than others, and as a result, theyre heavier. However, it isnt known why certain particles, such as the extremely corpulent top quark, are thousands of times more encumbered by the Higgs field than are lightweight particles, such as electrons and neutrinos. Theorists have been searching for some way to actually predict (particle) masses from first principles. No convincing theory has yet emerged, said John Gunion, author of The Higgs Hunters Guide (Basic Books, 1990) and a professor of physics at the University of California, Davis. [ Are There Higgs Bosons in Space? ] More science news from msnbc Great Ape Trust Bonobos getting tech-savvy with touchscreens Researchers are using touchscreens to add a new dimension to the already-formidable communication skills of bonobos, a chimplike primate species. Has the Higgs boson been found? Almost Search for Amelia Earharts plane to begin Fly decapitates ants, lives in their heads But heres where the Higgs particle comes in: Just as the photon mediates interactions with the EM field and is itself an excitation of the EM field, the Higgs particle mediates interactions with the Higgs field, and is itself an excitation of the Higgs field. Particles trudge through the Higgs field by exchanging virtual Higgs particles with it. And a real Higgs particle surfaces when the field becomes excited, like a slosh of the syrup. Detecting such a slosh (i.e. the particle) is how physicists can be sure the syrup (i.e. the field) exists. You have to get enough energy to excite the field so that it looks like a particle to us. Otherwise we dont know the field is there, Craig Blocker, a Higgs-hunting physicist at Brandeis University, told Lifes Little Mysteries. But because the Higgs particle is extremely high-energy (or, equivalently, very heavy), its tough to excite the Higgs field enough to create one. Thats where the Large Hadron Collider comes in: by smashing together high-speed protons, it generates enough juice to slosh the syrupy Higgs field around now and again, producing Higgs bosons. msnbc.msn/id/48062124/ns/technology_and_science-science/ HIGGS BOSON HUNT: WEVE DISCOVERED SOMETHING Analysis by Ian ONeill Mon Jul 2, 2012 12:17 PM ET After four years of high-energy particle demolition inside the detectors of the Large Hadron Collider (LHC), are physicists on the verge of announcing one of the most significant discoveries of our time? If youve seen this mornings headlines, then youd think the answer is a huge yes. But in typical quantum physics style, well have to wait a little longer for definitive proof for the elusive Higgs boson. So why all the excitement? WATCH VIDEO: THE LARGE HADRON COLLIDER news.discovery/videos/tech-lhc-collides-at-record-speeds.html PHOTOS: When the World Went Higgs Boson Crazy On Wednesday (July 4), scientists heading two major experiments at the LHC plan to announce their most recent findings at a physics conference in Australia with accompanying meetings in Geneva, Switzerland. Whats more, senior scientists at European Organization for Nuclear Research (CERN) are hinting that there is strong evidence in their data that suggests the Higgs boson exists. For the last year or so there have been hints of a Higgs detection, then those hints turned into potential evidence. Now, will we finally get word of a bona fide discovery? I agree that any reasonable outside observer would say, It looks like a discovery, CERN physicist John Ellis told The Associated Press. Weve discovered something which is consistent with being a Higgs. The Higgs boson is the last piece of the physics Standard Model, a collection of theories that underpin all modern physics. The Higgs particle is theorized to mediate mass -- like a photon (also a boson) mediates the electromagnetic force, i.e., light -- and creates the Higgs field that must pervade the entire Universe, endowing matter with mass. If the LHC didnt detect signs of the Higgs particle, its non-discovery would turn modern physics on its head. But physicists are an inquisitive bunch, so a non-discovery would be just as exciting (if not more so) than a discovery. But for all the Higgs doubters out there, its looking more and more likely the Higgs does exist and the Standard Model is as robust as physicists always thought. PHOTOS: Top 5 Misconceptions About The LHC So when the announcement comes from ATLAS and CMS physicists on Wednesday, will we get the definitive proof weve been (not-so-)patiently waiting for? In the world of high-energy physics, its not a question of slamming particles together and then photographing a Higgs boson screaming away from the carnage. Countless billions of collisions need to be recorded and the resulting spray of particles tracked. Like a photograph, more photons are needed to make the image appear defined and bright. If just a few photons hit the photographic paper, a very vague and fuzzy image is the result. The longer you leave the photograph under the light, more photons are collected and the better the image becomes. This is basically what the LHC scientists are doing. They repeat the same experiment again and again and collect the huge quantities of data to gradually build an image of the kinds of particles produced inside the LHC as it smashes protons together at near the speed of light. Over time, statistical spikes start to appear in the data, suggesting particles of a certain energy (or mass) are being detected. One statistical spike, at around the energy of one predicted variety of Higgs boson, has been growing stronger and more defined over the months, but at what point does that spike become a discovery and not just background noise? As this is a lesson in statistics of huge numbers, physicists have a way of categorizing how strong the signal is. HOWSTUFFWORKS: What is the Higgs boson? So far, the strength of this particular Higgs signal hasnt exceeded 4.3-sigma -- which relates to a 99.996 percent chance of the signal being real (and a 0.0004 percent chance that its just noise). A 5-sigma signal, on the other hand, is regarded as the Gold Standard in particle physics, relating to a 99.99994 percent chance that the signal is real (and only a 0.00006 percent chance of it being noise). Only when the signal hits that magical 5-sigma standard can a discovery be announced. This is why Ellis says that to any reasonable outside observer Wednesdays announcement will appear to confirm a Higgs boson discovery, but to particle physicists, the signal may be just shy of the 5-sigma mark. There is another possibility. By combining the results of both the CMS and ATLAS detectors, CERN can check the results of one against the other. In the pursuit of the Higgs, they also combine the data from both (which is how the previous 4.3-sigma signal was derived). On Wednesday, however, were not going to see a combined signal from both detectors. Combining the data from two experiments is a complex task, which is why it takes time, and why no combination will be presented on Wednesday, said CERN spokesman James Gillies. So this opens up another possibility: perhaps one of the detectors has a 5-sigma signal and the other does not. This could be the source of the ambiguity. Regardless, we may be getting close and few people are doubting that these results suggest a Higgs discovery will soon be confirmed. Only the most curmudgeonly will not believe that they have found it, said cosmologist Sean Carroll. But keep the Champagne on ice, that discovery announcement may still be some time off. https://facebook/photo.php?fbid=3467238601061&set=a.3445697342543.40414787.1273936657&type=3 news.discovery/space/higgs-boson-discovered-120702.html Confirmed: CERN discovers new particle likely to be the Higgs boson (VIDEO) Published: 04 July, 2012, 11:58 Edited: 04 July, 2012, 20:01 A representation of traces of a proton-proton collision measured in the Compact Muon Solenoid (CMS) experience in the search for the Higgs boson. (AFP Photo/CERN) (39.1Mb)embed video TAGS: SciTech Two teams of scientists at CERN have confirmed the discovery of a new subatomic particle, which may well be the elusive Higgs boson, also known as “the God particle”. I can confirm that a particle has been discovered that is consistent with the Higgs boson theory, said John Womersley, chief executive of the UKs Science & Technology Facilities Council. The result is still preliminary, but “its very strong and very solid,” according to Joe Incandela, spokesman for one of the two teams hunting for the Higgs particle. The CMS team is confident about its findings, which they say leave only a one in two million chance that the result they received could have happen if no Higgs boson existed. Both teams put the mass of the new particle at around 125 gigaelectronvolts (GeV) – corresponding to the predicted mass of the Higgs boson. The discovery is the strongest-yet in favor of the particle’s existence. So what is Higgs boson? The search for the Higgs boson has been, as the scientists presentation said, the work of thousands of people over many years, and lots of hours without sleep as they were probably justified in pointing out. They have been searching not just for the mysterious Higgs Boson particle, but specifically for the Standard Model Higgs. There is not just the particle, but also the theoretical model about its properties that the British scientist Peter Higgs has become so famous for. The Higgs boson is the last subatomic elemental particle predicted by the Standard Model to be discovered experimentally. The model is a fundamental part of quantum physics, which manages to incorporate three of the four known fundamental interactions – the electromagnetic, weak, and strong nuclear interactions – meaning only gravity is excluded. Since its formulation in the mid 20th century, Standard Model has been considered increasingly credible as new discoveries conformed to its predictions. The boson, which is responsible for elementary particles having mass, has evaded physicists’ eyes for decades, because they didn’t have the means to observe it. The Large Hadron Collider (LHC), the world’s biggest particle accelerator, was built partially for the purpose of finding the Higgs boson. However confusion still abounds about how the Higgs boson could be explained to laymen. At a press conference a journalist kicked off the questions session by asking, so what would you have us write, have you found the Higgs or what? What the team are more than 99% (but not quite 100%) sure of is that after hundreds of painstaking measurements they have indeed found a new particle never discovered before. This alone is a great discovery for science. It also seems likely that is the famed Higgs boson which could tell us so much about how our universe works and about why particles have mass. But scientists werent going to give the journalists the easy headline they wanted. It was too early to say they cautioned, to discern if it was really the particle they expected it to be. That would require years more work examining its properties. So what, even roughly, is this particle and what does it tell us? In response to such a question the panel turned the press curiosity back on itself. As CERN Director Ralf Heuern put it, You take a large room with journalists (laughter of course), and they are all equally distributed in the room. This is the field which would give mass to elementary particles through the interaction of these particles with the field…. But this field of journalists obviously has an interaction in between itself and this self interaction can produce this Higgs Boson. How can I imagine that? Imagine I open the door and I whisper a rumour into the room. Then the journalists are curious. They cluster, what did he say? This cluster of journalists is the Higgs Boson. Thats easy! Thats particle physics for laymen without a single equation. Asked about the funding of such a project the panel explained that is was a remarkable example of European collaboration and that because the companies involved in constructing the LHC were making research and development investments at the very forefront of technological innovation their returns for the project have been considerable. Signs of the particle were discovered through thousands of experiments at the LHC, where protons and antiprotons were smashed at almost-light speeds. The collisions produced new particles in their wake. Many of them can exist only fractions of seconds before decaying into lighter ones. Scientists were analyzing the resulting particles to establish what produced them and pinpoint the rare events of the appearance of the yet-unseen particle. They also had to ensure that what they got were actual sightings rather than quirks of probability, which rules quantum physics. The Higgs boson is often referred to as “the God particle” by the media. The name comes from the title of a popular science book by Leon Lederman, who nicknamed the particle in that way due to its importance to modern particle physics. However many scientists dislike the name, because it exaggerates the role the Higgs Boson actually plays. rt/news/cern-conference-higgs-boson-378/
Posted on: Wed, 13 Nov 2013 06:08:41 +0000
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