بوزون هیگز کشف شد! 

به گزارش نیوساینتیست، کامنتی در یکی از این وبلاگ‌ها که به نتایج آشکارساز اطلس اشاره می‌کند و باید بخشی از یک مقاله باشد احتمال کشف این ذره را تقویت کرده است. نویسنده ناشناس این نوشته به وجود جفت پروتون‌هایی بیشتر از حد انتظار در این آشکارساز با سطح انرژی 115 گیگاالکترون-ولت اشاره کرده است.

Follow events here as they unfold during the afternoon, including the announcement, the key data and reaction from around the world.

The Higgs boson is a subatomic particle that was predicted to exist nearly 50 years ago. Scientists have been searching for the particle for decades, but so far have no solid proof that it is real.

Although the Higgs boson grabs headlines � unsurprising, given its nickname, the God particle � it is important only because its discovery would prove there is an invisible energy field that fills the vacuum throughout the observable universe. Without the field, or something like it, we would not be here.

Scientists have no hope of seeing the field itself, so they search instead for its signature particle, the Higgs boson, which is essentially a ripple in the Higgs field.

According to theory, the Higgs field switched on a trillionth of a second after the big bang blasted the universe into existence. Before this moment, all of the particles in the cosmos weighed nothing at all and zipped around chaotically at the speed of light.

When the Higgs field switched on, some particles began to feel a "drag" as they moved around, as though caught in cosmic glue. By clinging to the particles, the field gave them mass, making them move around more slowly. This was a crucial moment in the formation of the universe, because it allowed particles to come together and form all the atoms and molecules around today.

But the Higgs field is selective. Particles of light, or photons, move through the Higgs field as if it wasn't there. Because the field does not cling top them, they remain weightless and destined to move around at the speed of light forever. Other particles, like quarks and electrons � the smallest constituents of atoms � get caught in the field and gain mass in the process.

The field has enormous implications. Without it, the smallest building blocks of matter, from which all else is made, would forever rush around at the speed of light. They would never come together to make stars, planets, or life as we know it.

Atlas and CMS have presented an important milestone in their search for the Higgs particle, but it is not yet sufficient for a proper discovery given the amount of data recorded so far. Still, I am very excited about it, since the quality of the LHC results is exceptional.
The Higgs particle seems to have picked itself a mass which makes things very difficult for us physicists. Everything points at a mass in the range 115-140GeV and we concentrate on this region with our searches at the LHC and at the Tevatron.

The results indicate we are about half-way there and within one year we will probably know whether the Higgs particle exists with absolute certainty, but it is unfortunately not a Christmas present this year. The Higgs particle will, of course, be a great discovery, but it would be an even greater discovery if it didn't exist where theory predicts it to be. This would be a huge surprise and secretly we hope this might happen. If this is case, there must be something else that takes the role of the "standard" Higgs particle, perhaps a family of several Higgs particles or something even more exotic. The unexpected is always the most exciting.

1.43pm: From Cern: "#ATLAS sees a small excess at a Higgs mass of 126 GeV coming from 3 channels. Local significance: 3.6 sigma but only 2.4 sigma globally"

1.49pm: Fabiola Gianotti has finished her presentation. So far, we know that Atlas seems to have found evidence for a bump around 126GeV for something that looks like the Higgs.

Next up is Guido Tonelli, spokesperson for Cern's other main detector, the Compact Muon Solenoid (CMS). As @iansample says, "So. What we're looking for now is whether CMS detector has seen Higgs-like signals around the same mass (126GeV)."

1.56pm: Via the Science Media Centre, Dr Claire Shepherd-Themistocleus, head of the CMS group at the STFC Rutherford Appleton Laboratory, said: "We are homing in on the Higgs. We have had hints today of what its mass might be and the excitement of scientists is palpable. Whether this is ultimately confirmed or we finally rule out a low mass Higgs boson, we are on the verge of a major change in our understanding of the fundamental nature of matter."

2.15pm: CMS has released an image of the results of a proton-proton collision (main pic above) in which you can see four high-energy electrons (green lines and red towers). This shows the characteristics expected from the decay of a Higgs boson.

2.19pm: From @stevengoldfarb, who is a physicist, outreach, education and communication coordinator on Atlas experiment at Cern: "Looks like our colleagues from #CMS see similar excesses near 125 GeV. 2012 will be fun! #ATLAS #LHC #CERN #Higgs"

2.23pm: A succinct update of information so far by Eugenie Samuel Reich over at Nature News:

The latest results narrow the field even more: Atlas has excluded all masses outside the range of 115�130 GeV, and the CMS team has revised the range to 117�127 GeV. Raising anticipation still further, each experiment separately reports that the LHC's high-energy collisions between protons generated an excess of particles that could be the products of Higgs particle production. The ATLAS result is consistent with a 125�126 GeV Higgs at a statistical level of at most 3.6 standard deviations, and the CMS team reports a 124GeV signal of at most 2.6 standard deviations. In particle physics, a statistical significance of five standard deviations is considered to be proof of a particle's existence, and three standard deviations to be evidence that a particle may exist. The Atlas and CMS results have not yet been combined, so a joint probability is not available.

The situation is further complicated, says Samuel Reich, by another signal seen by both experiments at around 119 GeV. Though this is a weaker signal, its presence has made scientists cautious in interpreting what is real and what is not in the new data. A sighting of the Higgs boson at either energy is consistent with the Standard Model of particle physics, and also with its extension, known as supersymmetry.

2.32pm: Guido Tonelli's presentation on CMS data seems to suggest that scientists cannot exclude a Higgs below 127GeV. This complicates the picture from Atlas results slightly, which seemed to favour a Higgs around 127GeV.

From @Cern: "All channels combined, #CMS excludes a #Higgs mass from 127 GeV to 600 GeV; sees small excess at 1.9 sigma level below 130 GeV"

2.36pm: Guido Tonelli finishes his talk with a dedication to his father, who died on Sunday.

2.36pm: Now over to questions �

2.46pm: Over at the New York Times, Dennis Overbye writes that there have been "tantalising hints" but no direct proof of the Higgs.

2.54pm: Cern director Rolf Heuer winds up the seminar: "These are preliminary results, we're talking small numbers, and remember that we are running [the LHC] next year. The window for the Higgs mass gets smaller and smaller but it is still alive. We have not found it yet. Stay tuned for next year."

Cern has also published its press release:

3.00pm: Here's the New Scientist take by Lisa Grossman on this afternoon's seminars:

3.25pm: While we wait for the press conference to start, here's some more analysis. This article on "Higgs mania" from the excellent In The Dark blog starts with the writer being woken at 7am with hints on the radio that the Higgs would be announced later today:

From Cern's rival particle accelerator, Fermilab, a press release outlining the results as they see them:

3.37pm: Rolf Heuer sits down with Guido Tonelli of CMS to begin the press conference. Camera bulbs flashing everywhere. I assume this is what it's like at all science seminars, yes?

3.40pm: Press conference begins. If you have questions, you can tweet them to the Cern press office with the hashtag #higgsupdate

4.09pm: Press conference ends with Rolf Heuer stating: "See you next year with a discovery."

Reacting to today's announcements from Cern, Columbia University physicist Brian Greene said:

5.24pm: Our man at Cern, Guardian science correspondent Ian Sample, has filed his story about today's announcement, including physicists' reactions.

 Source: The Gardian

While the results are not conclusive � the hints of the particle could fade when the LHC collects more data next year � they are the strongest evidence so far that the Higgs particle is there to be found.

"We have narrowed down the region where the Higgs particle is most likely to be, and we see some interesting signals, but we need more data before we can reach any firm conclusions," said Gianotti, who heads the team that works on the collider's enormous Atlas detector. "It's been a busy time, but a very exciting time."

Finding the Higgs boson has been a major goal for the �10bn LHC after a less powerful machine at Cern called LEP failed to find the missing particle before it closed for business in 2000.

Ben Allanach, a theoretical physicist at Cambridge University, said: "My own personal feeling is that they probably have some kind of Higgs. Of course, discovery cannot be officially claimed yet, but I do feel in my heart of hearts that we have just seen the precursor to a discovery announcement."

According to the Higgs theory, an invisible energy field fills the vacuum of space throughout the universe. When some particles move through the field they feel drag and gain weight as a result. Others, such as particles of light, or photons, feel no drag at all and remain massless.

Without the field � or something to do its job � all fundamental particles would weigh nothing and hurtle around at the speed of light. That would spell disaster for the formation of atoms in the early universe and rule out life as we know it.

Scientists have no hope of detecting the field itself, but discovery of the Higgs boson would prove that it exists.

While the field is thought to give mass to fundamental particles, including quarks and electrons (the two kinds of particles that make up atoms), it accounts for only one or two percent of the weight of an atom itself, or any everyday object. That is because most mass comes from the energy that glues quarks together inside atoms.

To hunt for the Higgs boson physicists at the LHC sift through showers of subatomic debris that spew out when protons collide in the machine at close to the speed of light. Most of the energy released in these microscopic fireballs is converted into well known particles that are identified by the collider's giant detectors. Occasionally the collisions might create a Higgs boson, but it is expected that it would disintegrate immediately into more familiar particles. To find it scientists must look for telltale "excesses" of particles. They appear as bumps, or peaks, in data.

Particle physicists use a "sigma" scale to grade the significance of results, from one to five. One and two sigma results are unreliable because they come and go with statistical fluctuations in the data. A three sigma result counts as an "observation", while a five sigma result is enough to claim an official discovery. There is less than a one in a million chance of a five sigma result being a statistical fluke.

Gianotti and Tonelli led two separate teams � one using Cern's Atlas detector, the other using the laboratory's Compact Muon Solenoid. At their seminar yesterday one team reported a 2.3 sigma bump in their data that could be a Higgs boson weighing 126GeV, while the other reported a 1.9 sigma Higgs signal at a mass of around 124GeV. There is a 1% chance that the Atlas result could be due to a random fluctuation in the data.

Oliver Buchmueller, a physicist on the CMS experiment, said: "We see a small bump around the same mass as the Atlas team and that is intriguing. It means we have two experiments seeing the same thing and that is exactly how we would expect a Higgs signal to build up."

Early next year the Atlas and CMS teams will pool their results, a move that should see the signals strengthen. Both teams are expected to need around four times as much data before they can finally confirm whether or not the Higgs boson exists. That might be difficult to collect before the end of next year, when the machine is due to close for at least a year for an upgrade before it can run at its full design power.

"There is definitely a hint of something around 125GeV but it's not a discovery yet. We need more data! I'm keeping my champagne on ice," said Jeff Forshaw, a physicist at Manchester University. "It should be said this is a fantastic achievement by all concerned. The machine has been working wonderfully and it is great to be closing in on the Higgs so soon."

The director general of Cern, Rolf-Dieter Heuer, said: "I find it fantastic that we have the first results in the search for the Higgs, but keep in mind these are preliminary results. The window for the Higgs mass gets smaller and smaller, however it is still alive. But be careful, � it's intriguing hints in several channels, in two experiments, but we have not found it yet, we have not excluded it yet."

If the glimpse of the Higgs boson turns into a formal sighting next year it may be one of several Higgs particles outlined in a radical theory of nature called supersymmetry, which says every known type of particle has an undiscovered twin. It is popular among many physicists because it explains how some of the forces of nature might have behaved as one in the early universe. Unifying these fundamental forces was a feat that eluded Einstein to the grave.

Dick Hagen, a physicist at Rochester University who helped to develop the Higgs theory in 1964, said: "Einstein once said that God may be subtle but he is not perverse. Today's results seem to favour the simplest manifestation of [the Higgs mechanism], and that is very gratifying as it coincides with the choice we made in 1964 � not to mention the more personal issue that more complicated versions could easily fail to appear in the lifetimes of its principal authors."