What The Latest LHC Revelations Say about The Higgs Boson and ‘Five Sigma’

In December 2011, the elusive Higgs boson was back in the limelight whenhints of the particle emerged in the wreckage of proton collisions at the world’s most powerful particle smasher – the Large Hadron Collider (LHC) near Geneva, Switzerland.

There have been no new collisions since, but researchers from the LHC’s two main detectors have given the existing data a more careful look, culminating in two fresh Higgs analyses released on Tuesday. Here New Scientistdisentangles what we can and can’t conclude about the particle that is swiftly becoming the people’s favourite

Remind me: What was the scoop in December?
The Higgs boson is the missing piece of the standard model of physics, the leading theory for how particles and forces interact. The Higgs is thought to endow others with mass but has yet to be positively observed, so its mass – and existence – are still unconfirmed.

In December, the LHC’s two main particle detectors, CMS and ATLAS, each reported excesses of events, such as the appearance of a pair of photons in the shrapnel from particle collisions. These excess events could be due to a Higgs with a mass of around 125 gigaelectron volts (GeV; particle masses and energy can be treated interchangeably).

Great. End of story?
Far from it. Since more mundane reactions can produce such events too, they do not provide definitive evidence for the Higgs.

By convention, researchers only declare a discovery when an anomaly reaches a statistical significance known as 5 sigma, which means there is less than a 1-in-a-million chance it is just a fluke. The size of the anomalies reported by the two detectors in seminar in December was 1.9 sigma for CMS and 2.5 sigma for ATLAS, which indicate a probability of a fluke of roughly 1 per cent.

So what’s the latest?
After taking a closer look at the data, ATLAS finds little need for revision,reporting the same 2.5 sigma significance as before. But the CMS analysis reports some extra events that were not analysed in time for LHC’s December announcement. These events could be due to a Higgs boson of around 125 GeV decaying into a pair of photons – after being produced from the collision of two particles called W and Z bosons, that transmit the weak force.

Adding these events to the December analysis gives a small boost to the overall statistical significance of CMS’s Higgs hint, which now stands at 2.1 sigma. “It’s not a radically different picture,” says Greg Landsberg of Brown University in Providence, Rhode Island, who works on CMS.

What’s this about 4.3 sigma, then?
A blog post on the Nature website on Tuesday states that an unofficial synthesis of the two results gives a significance of 4.3 sigma. But Pauline Gagnon of ATLAS says it would be premature to reach that conclusion before the Moriond conference in La Thuile, Italy, in March. “Combining the two experiments may happen after the first week of March but not before,” she says. “Until then, it is anyone’s guess.”

Will combining the CMS and ATLAS results boost the significance?
Not necessarily, Landsberg says. The two detectors do not see an excess at exactly the same mass: CMS sees one at 124 GeV, ATLAS at 126 GeV. That might be due to errors in mass measurements by at least one of the detectors, in which case further analysis could bring the two masses into line.

The other possibility is that they are both seeing flukes that happened to show up at nearly the same mass. “You have to carefully sift through different sources of uncertainties,” warns Landsberg, to figure out which answer is more likely.

When will we know whether the Higgs is out there?
More data will be needed. The LHC will start up again in late March or early April after its winter shutdown. CERN officials are still trying to decide whether to boost the energy of this year’s collisions from 7000 GeV to 8000 GeV. A decision could be announced as early as Friday, says Laurent Serin of the French National Institute of Nuclear and Particle Physics (CNRS/IN2P3).

If the Higgs exists, collisions at the higher energy would produce more Higgs particles, making it easier to spot. Either way, the LHC will confirm or rule out the Higgs by the end of 2012, says Landsberg. “It’s a very exciting year, and hopefully a year from now I can point to discovery papers.”

Dr. Peter Higgs 

Dr. Peter Higgs 


Inside the control room of CMS, CERN.

Inside the control room of CMS, CERN.

wonder-fullmusings:

superkrupaninja:

HE KNEW.

omg, Tesla totally knew.

wonder-fullmusings:

superkrupaninja:

HE KNEW.

omg, Tesla totally knew.


DEEP BREATH. In. Out. Be calm.
You might have heard some news about something called a “neutrino” that might have moved faster than the speed of light. This news is out of CERN, in Europe, and like Ron Burgundy, it’s kind of a big deal.
Remember Einstein’s E=mc² equation? Well, that wouldn’t exactly be ruined, but relativity would need to be seriously adjusted. As Phil Plait put it, it would turn so much of physics upside-down that it’s like saying “… that gravity pushes, not pulls.” So what did they observe?
A neutrino is a particular subatomic particle, like an uncharged electron. They travel, well, very fast, and can go through matter. Photons are light, and they travel at (wait for it) the speed of light. According to what we know up to now, neutrinos should travel fast, but according to the laws of physics not as fast as light. That’s where the CERN experiment comes in.
The scientists at CERN set up a detector at a very exact distance away from a source of photons and neutrinos. When I say exact I mean exact. Like so precise that they could be within a meter or so of error at a distance of 730 km apart. They know how fast light travels, and it should have taken about 2.43 milliseconds for the light to reach the detector in Italy from CERN. According to the scientists, the neutrinos arrived 60 nanoseconds before the light.
The Swiss are impeccable time-keepers.
They report that their error is within 10 nanoseconds, so it’s a significant result. But there are a couple of problems. Not problems that for sure disprove it, but certainly give reason for caution.
It’s very hard to know exactly when neutrinos are created in whatever source you are shooting them from. So the “start” point is a little fuzzy.
As noted at Bad Astronomy, a supernova called 1987a throws some more cold water on this. See, that supernova was 160,000 light years away. So if neutrinos traveled faster than light by the same ratio as above, we would have seen the 1987a neutrinos about four years before the light. And that didn’t happen.
Neutrinos are pesky little things, and very hard to control and measure, being as they flow right through planets and the like.
The scientists had a webcast from CERN today, and they are being very careful to say that this needs to be checked and über-checked, and then repeated again after that. They also claim no theoretical re-writes of history. The problem is that the press is not being nearly so cautious.
So take a deep breath, relax, let their fellow scientists and the skeptics have at it for a while, and don’t be sad if this turns out to not be as big a deal as thought. Of course, it might be true, but when it comes to extraordinary claims, you have to provide extraordinary proof.

DEEP BREATH. In. Out. Be calm.

You might have heard some news about something called a “neutrino” that might have moved faster than the speed of light. This news is out of CERN, in Europe, and like Ron Burgundy, it’s kind of a big deal.

Remember Einstein’s E=mc² equation? Well, that wouldn’t exactly be ruined, but relativity would need to be seriously adjusted. As Phil Plait put it, it would turn so much of physics upside-down that it’s like saying “… that gravity pushes, not pulls.” So what did they observe?

A neutrino is a particular subatomic particle, like an uncharged electron. They travel, well, very fast, and can go through matter. Photons are light, and they travel at (wait for it) the speed of light. According to what we know up to now, neutrinos should travel fast, but according to the laws of physics not as fast as light. That’s where the CERN experiment comes in.

The scientists at CERN set up a detector at a very exact distance away from a source of photons and neutrinos. When I say exact I mean exact. Like so precise that they could be within a meter or so of error at a distance of 730 km apart. They know how fast light travels, and it should have taken about 2.43 milliseconds for the light to reach the detector in Italy from CERN. According to the scientists, the neutrinos arrived 60 nanoseconds before the light.

The Swiss are impeccable time-keepers.

They report that their error is within 10 nanoseconds, so it’s a significant result. But there are a couple of problems. Not problems that for sure disprove it, but certainly give reason for caution.

  1. It’s very hard to know exactly when neutrinos are created in whatever source you are shooting them from. So the “start” point is a little fuzzy.
  2. As noted at Bad Astronomy, a supernova called 1987a throws some more cold water on this. See, that supernova was 160,000 light years away. So if neutrinos traveled faster than light by the same ratio as above, we would have seen the 1987a neutrinos about four years before the light. And that didn’t happen.
  3. Neutrinos are pesky little things, and very hard to control and measure, being as they flow right through planets and the like.

The scientists had a webcast from CERN today, and they are being very careful to say that this needs to be checked and über-checked, and then repeated again after that. They also claim no theoretical re-writes of history. The problem is that the press is not being nearly so cautious.

So take a deep breath, relax, let their fellow scientists and the skeptics have at it for a while, and don’t be sad if this turns out to not be as big a deal as thought. Of course, it might be true, but when it comes to extraordinary claims, you have to provide extraordinary proof.


Particles found to break speed of light

(Reuters) - An international team of scientists said on Thursday they had recorded sub-atomic particles traveling faster than light — a finding that could overturn one of Einstein’s long-accepted fundamental laws of the universe.
 
Antonio Ereditato, spokesman for the researchers, told Reuters that measurements taken over three years showed neutrinos pumped from CERN near Geneva to Gran Sasso in Italy had arrived 60 nanoseconds quicker than light would have done.
 
“We have high confidence in our results. We have checked and rechecked for anything that could have distorted our measurements but we found nothing,” he said. “We now want colleagues to check them independently.”

If confirmed, the discovery would undermine Albert Einstein’s 1905 theory of special relativity, which says that the speed of light is a “cosmic constant” and that nothing in the universe can travel faster.

That assertion, which has withstood over a century of testing, is one of the key elements of the so-called Standard Model of physics, which attempts to describe the way the universe and everything in it works.

The totally unexpected finding emerged from research by a physicists working on an experiment dubbed OPERA run jointly by the CERN particle research center near Geneva and the Gran Sasso Laboratory in central Italy.

A total of 15,000 beams of neutrinos — tiny particles that pervade the cosmos — were fired over a period of 3 years from CERN toward Gran Sasso 730 (500 miles) km away, where they were picked up by giant detectors.

Light would have covered the distance in around 2.4 thousandths of a second, but the neutrinos took 60 nanoseconds — or 60 billionths of a second — less than light beams would have taken.

“It is a tiny difference,” said Ereditato, who also works at Berne University in Switzerland, “but conceptually it is incredibly important. The finding is so startling that, for the moment, everybody should be very prudent.”

Ereditato declined to speculate on what it might mean if other physicists, who will be officially informed of the discovery at a meeting in CERN on Friday, found that OPERA’s measurements were correct.

“I just don’t want to think of the implications,” he told Reuters. “We are scientists and work with what we know.”

Much science-fiction literature is based on the idea that, if the light-speed barrier can be overcome, time travel might theoretically become possible.

The existence of the neutrino, an elementary sub-atomic particle with a tiny amount of mass created in radioactive decay or in nuclear reactions such as those in the Sun, was first confirmed in 1934, but it still mystifies researchers.

It can pass through most matter undetected, even over long distances, and without being affected. Millions pass through the human body every day, scientists say.

To reach Gran Sasso, the neutrinos pushed out from a special installation at CERN — also home to the Large Hadron Collider probing the origins of the universe — have to pass through water, air and rock.

The underground Italian laboratory, some 120 km (75 miles) to the south of Rome, is the largest of its type in the world for particle physics and cosmic research.

Around 750 scientists from 22 different countries work there, attracted by the possibility of staging experiments in its three massive halls, protected from cosmic rays by some 1,400 metres (4,200 feet) of rock overhead.

Particles found to break speed of light

(Reuters) - An international team of scientists said on Thursday they had recorded sub-atomic particles traveling faster than light — a finding that could overturn one of Einstein’s long-accepted fundamental laws of the universe.

 

Antonio Ereditato, spokesman for the researchers, told Reuters that measurements taken over three years showed neutrinos pumped from CERN near Geneva to Gran Sasso in Italy had arrived 60 nanoseconds quicker than light would have done.

 

“We have high confidence in our results. We have checked and rechecked for anything that could have distorted our measurements but we found nothing,” he said. “We now want colleagues to check them independently.”

If confirmed, the discovery would undermine Albert Einstein’s 1905 theory of special relativity, which says that the speed of light is a “cosmic constant” and that nothing in the universe can travel faster.

That assertion, which has withstood over a century of testing, is one of the key elements of the so-called Standard Model of physics, which attempts to describe the way the universe and everything in it works.

The totally unexpected finding emerged from research by a physicists working on an experiment dubbed OPERA run jointly by the CERN particle research center near Geneva and the Gran Sasso Laboratory in central Italy.

A total of 15,000 beams of neutrinos — tiny particles that pervade the cosmos — were fired over a period of 3 years from CERN toward Gran Sasso 730 (500 miles) km away, where they were picked up by giant detectors.

Light would have covered the distance in around 2.4 thousandths of a second, but the neutrinos took 60 nanoseconds — or 60 billionths of a second — less than light beams would have taken.

“It is a tiny difference,” said Ereditato, who also works at Berne University in Switzerland, “but conceptually it is incredibly important. The finding is so startling that, for the moment, everybody should be very prudent.”

Ereditato declined to speculate on what it might mean if other physicists, who will be officially informed of the discovery at a meeting in CERN on Friday, found that OPERA’s measurements were correct.

“I just don’t want to think of the implications,” he told Reuters. “We are scientists and work with what we know.”

Much science-fiction literature is based on the idea that, if the light-speed barrier can be overcome, time travel might theoretically become possible.

The existence of the neutrino, an elementary sub-atomic particle with a tiny amount of mass created in radioactive decay or in nuclear reactions such as those in the Sun, was first confirmed in 1934, but it still mystifies researchers.

It can pass through most matter undetected, even over long distances, and without being affected. Millions pass through the human body every day, scientists say.

To reach Gran Sasso, the neutrinos pushed out from a special installation at CERN — also home to the Large Hadron Collider probing the origins of the universe — have to pass through water, air and rock.

The underground Italian laboratory, some 120 km (75 miles) to the south of Rome, is the largest of its type in the world for particle physics and cosmic research.

Around 750 scientists from 22 different countries work there, attracted by the possibility of staging experiments in its three massive halls, protected from cosmic rays by some 1,400 metres (4,200 feet) of rock overhead.