Particle Physicists Put the Squeeze on the Higgs Boson; Look for Conclusive Results in 2012

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With “freshly squeezed” plots from the latest data garnered by two particle physics experiments, teams of scientists from the Large Hadron Collider at CERN, the European Center for Nuclear Research, said Tuesday they had recorded “tantalizing hints” of the elusive subatomic particle known as the Higgs Boson, but cannot conclusively say it exists … yet. However, they predict that 2012 collider runs should bring enough data to make the determination.

“The very fact that we are able to show the results of very sophisticated analysis just one month after the last bit of data we used has been recorded is very reassuring,” Dr. Greg Landsberg, physics coordinator for the Compact Muon Solenoid (CMS) detector at the LHC told Universe Today. “It tells you how quick the turnaround time is. This is truly unprecedented in the history of particle physics, with such large and complex experiments producing so much data, and it’s very exciting.”

For now, the main conclusion of over 6,000 scientists on the combined teams from CMS and the ATLAS particle detectors is that they were able to constrain the mass range of the Standard Model Higgs boson — if it exists — to be in the range of 116-130 GeV by the ATLAS experiment, and 115-127 GeV by CMS.

The Standard Model is the theory that explains the interactions of subatomic particles – which describes ordinary matter that the Universe is made of — and on the whole works very well. But it doesn’t explain why some particles have mass and others don’t, and it also doesn’t describe the 96% of the Universe that is invisible.

In 1964, physicist Peter Higgs and colleagues proposed the existence of a mysterious energy field that interacts with some subatomic particles more than others, resulting in varying values for particle mass. That field is known as the Higgs field, and the Higgs Boson is the smallest particle of the Higgs field. But the Higgs Boson hasn’t been discovered yet, and one of the main reasons the LHC was built was to try to find it.

To look for these tiny particles, the LHC smashes high-energy protons together, converting some energy to mass. This produces a spray of particles which are picked up by the detectors. However, the discovery of the Higgs relies on observing the particles these protons decay into rather than the Higgs itself. If they do exist, they are very short lived and can decay in many different ways. The problem is that many other processes can also produce the same results.

How can scientists tell the difference? A short answer is that if they can figure out all the other things that can produce a Higgs-like signal and the typical frequency at which they will occur, then if they see more of these signals than current theories suggest, that gives them a place to look for the Higgs.

The experiments have seen excesses in similar ranges. And as the CERN press release noted, “Taken individually, none of these excesses is any more statistically significant than rolling a die and coming up with two sixes in a row. What is interesting is that there are multiple independent measurements pointing to the region of 124 to 126 GeV.”

“This is very promising,” said Landsberg, who is also a professor at Brown University. “This shows that both experiments understand what is going on with their detectors very, very well. Both calibrations saw excesses at low masses. But unfortunately the nature of our process is statistical and statistics is known to play funny tricks once in a while. So we don’t really know — we don’t have enough evidence to know — if what we saw is a glimpse of the Higgs Boson or these are just statistical fluctuations of the Standand Model process which mimic the same type of signatures as would come if the Higgs Boson is produced.”

Landsberg said the only way to cope with statistics is to get more data, and the scientists need to increase the size of the data samples considerably in order to definitely answer the question on whether the Higgs Boson exists at the mass of 125 GeV or any mass range which hasn’t been excluded yet.

The good news is that loads of data are coming in 2012.

“We hope to quadruple the data sample collected this year,” Landsberg said. “And that should give us enough statistical confidence to essentially solve this puzzle and tell the world whether we saw the first glimpses of the Higgs Boson. As the team showed today, we will keep increasing until we reach a level of statistical significance which is considered to be sufficient for discovery in our field.”

Landsberg said that within this small range, there is not much room for the Higgs to hide. “This is very exciting, and it tells you that we are almost there. We have enough sensitivity and beautiful detectors; we need just a little bit more time and a little more data. I am very hopeful we should be able to say something definitive by sometime next year.”

So the suspense is building and 2012 could be the year of the Higgs.

More info: CERN press release, ArsTechnica

Neutrinos Still Breaking Speed Limits

Particle Collider

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New test results are in from OPERA and it seems those darn neutrinos, they just can’t keep their speed down… to within the speed of light, that is!

report released in September by scientists working on the OPERA project (Oscillation Project with Emulsion-tracking Apparatus) at Italy’s Gran Sasso research lab claimed that neutrinos emitted from CERN 500 miles away in Geneva arrived at their detectors 60 nanoseconds earlier than expected, thus traveling faster than light. This caused no small amount of contention in the scientific community and made news headlines worldwide – and rightfully so, as it basically slaps one of the main tenets of modern physics across the face.

Of course the scientists at OPERA were well aware of this, and didn’t make such a proclamation lightly; over two years of repeated research was undergone to make sure that the numbers were accurate… as well as could be determined, at least. And they were more than open to having their tests replicated and the results reviewed by their peers. In all regards their methods were scientific yet skepticism was widespread… even within OPERA’s own ranks.

One of the concerns that arose regarding the discovery was in regards to the length of the neutrino beam itself, emitted from CERN and received by special detector plates at Gran Sasso. Researchers couldn’t say for sure that any neutrinos detected were closer to the beginning of the beam versus the end, a disparity (on a neutrino-sized scale anyway) of 10.5 microseconds… that’s 10.5 millionths of a second! And so in October, OPERA requested that proton pulses be resent – this time lasting only 3 nanoseconds each.

The OPERA Neutrino Detector

The results were the same. The neutrinos arrived at Gran Sasso 60 nanoseconds earlier than anticipated: faster than light.

The test was repeated – by different teams, no less – and so far 20 such events have been recorded. Each time, the same.

Faster. Than light.

What does this mean? Do we start tearing pages out of physics textbooks? Should we draw up plans for those neutrino-powered warp engines? Does Einstein’s theory of relativity become a quaint memento of what we used to believe?

Hardly. Or, at least, not anytime soon.

OPERA’s latest tests have managed to allay one uncertainty regarding the results, but plenty more remain. One in particular is the use of GPS to align the clocks at the beginning and end of the neutrino beam. Since the same clock alignment system was used in all the experiments, it stands that there may be some as-of-yet unknown factor concerning the GPS – especially since it hasn’t been extensively used in the field of high-energy particle physics.

In addition, some scientists would like to see more results using other parts of the neutrino detector array.

Of course, like any good science, replication of results is a key factor for peer acceptance. And thus Fermilab in Batavia, Illinois will attempt to perform the same experiment with its MINOS (Main Injector Neutrino Oscillation Search) facility, using a precision matching OPERA’s.

MINOS hopes to have its independent results as early as next year.

No tearing up any textbooks just yet…

 

Read more in the Nature.com news article by Eugenie Samuel Reich. The new result was released on the arXiv preprint server on November 17. (The original September 2011 OPERA team paper can be found here.)

Special Relativity May Answer Faster-than-Light Neutrino Mystery

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Oh, yeah. Moving faster than the speed of light has been the hot topic in the news and OPERA has been the key player. In case you didn’t know, the experiment unleashed some particles at CERN, close to Geneva. It wasn’t the production that caused the buzz, it was the revelation they arrived at the Gran Sasso Laboratory in Italy around 60 nanoseconds sooner than they should have. Sooner than the speed of light allows!

Since the announcement, the physics world has been on fire, producing more than 80 papers – each with their own opinion. While some tried to explain the effect, others discredited it. The overpowering concensus was the OPERA team simply must have forgotten one critical element. On October 14, 2011, Ronald van Elburg at the University of Groningen in the Netherlands put forth his own statement – one that provides a persuasive point that he may have found the error in the calculations.

To get a clearer picture, the distance the neutrinos traveled is straightforward. They began in CERN and were measured via global positioning systems. However, the Gran Sasso Laboratory is located beneath the Earth under a kilometre-high mountain. Regardless, the OPERA team took this into account and provided an accurate distance measurement of 730 km to within tolerances of 20 cm. The neutrino flight time is then measured by using clocks at the opposing ends, with the team knowing exactly when the particles left and when they landed.

But were the clocks perfectly synchronized?

Keeping time is again the domain of the GPS satellites which each broadcasting a highly accurate time signal from orbit some 20,000km overhead. But is it possible the team overlooked the amount of time it took for the satellite signals to return to Earth? In his statement, van Elburg says there is one effect that the OPERA team seems to have overlooked: the relativistic motion of the GPS clocks.

Sure, radio waves travel at the speed of light, so what difference does the satellite position make? The truth is, it doesn’t.. but the time of flight does. Here we have a scenario where one clock is on the ground while the other is orbiting. If they are moving relative to one another, this calculation needs to be included in the findings. The orbiting probes are positioned from West to East in a plane inclined at 55 degrees to the equator… almost directly in line with the neutrino flight path. This means the clock on the GPS is seeing the neutrino source and detector as changing.

“From the perspective of the clock, the detector is moving towards the source and consequently the distance travelled by the particles as observed from the clock is shorter,” says van Elburg.

According to the news source, he means shorter than the distance measured in the reference frame on the ground and the OPERA team overlooks this because it thinks of the clocks as on the ground not in orbit. Van Elburg calculates that it should cause the neutrinos to arrive 32 nanoseconds early. But this must be doubled because the same error occurs at each end of the experiment. So the total correction is 64 nanoseconds, almost exactly what the OPERA team observes.

Is this the final answer for traveling faster than the speed of light? No. It’s just another possible answer to explain a new riddle… and a confirmation of a new revelation.

Original Story Source: Technology Review News Release. For Further Reading: Can apparent superluminal neutrino speeds be explained as a quantum weak measurement?.

Particle Physics and Faster-Than-Light Neutrinos…Discuss.

On September 22, an international team of researchers working on the OPERA project at the Gran Sasso research facility released a paper on some potentially physics-shattering findings: beams of neutrinos that had traveled from the CERN facility near Geneva to their detector array outside of Rome at a speed faster than light. (Read more about this here and here.) Not a great deal faster, to be sure – only 60 nanoseconds faster than expected – but still faster. There’s been a lot of recoil from the scientific community about this announcement, and rightly so, since if it does end up being a legitimate finding then it would force us to rework much of what we have come to know about physics ever since Einstein’s theory of relativity.

Of course, to those of us not so well-versed in particle physics *raises hand* a lot of this information can quickly become overwhelming, to say the least. Thankfully the folks at Sixty Symbols have recorded this interview with two astrophysicists at the UK’s University of Nottingham. It helps explain some of the finer points of the discovery, what it means and what the science community in general thinks about it. Check it out!

Thanks to Dan Satterfield for posting this at his Wild Wild Science blog.

Faster Than The Speed Of Light… OPERA Update

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A few days ago, the physics world was turned upside down at the announcement of “faster than the speed of light”. The mighty neutrino has struck again by breaking the cosmic speed limit and traveling at a velocity 20 parts per million above light speed. To absolutely verify this occurrence, collaboration is needed from different sources and we’re here to give you the latest update.

“This result comes as a complete surprise,” said OPERA spokesperson, Antonio Ereditato of the University of Bern. “After many months of studies and cross checks we have not found any instrumental effect that could explain the result of the measurement. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation.”

Since the OPERA measurements go against everything we think we know, it’s more important than ever to verify its findings through independent research.

“When an experiment finds an apparently unbelievable result and can find no artifact of the measurement to account for it, it’s normal procedure to invite broader scrutiny, and this is exactly what the OPERA collaboration is doing, it’s good scientific practice,” said CERN Research Director Sergio Bertolucci. “If this measurement is confirmed, it might change our view of physics, but we need to be sure that there are no other, more mundane, explanations. That will require independent measurements.”

To get the job done, the OPERA Collaboration joined forces with CERN metrology experts and other facilities to establish absolute calibrations. There cannot be any error margin in parameters between the source and detector distances – and the neutrino’s flight time. In this circumstance, the measurements of the initial source of the neutrino beam and OPERA has an uncertainty value of 20 cm over the 730 km. The neutrino flight time has an accuracy of less than 10 nanoseconds, and was confirmed through the use of highly regarded GPS equipment and an atomic clock. Every care was given to ensure precision.

“We have established synchronization between CERN and Gran Sasso that gives us nanosecond accuracy, and we’ve measured the distance between the two sites to 20 centimetres,” said Dario Autiero, the CNRS researcher who will give this afternoon’s seminar. “Although our measurements have low systematic uncertainty and high statistical accuracy, and we place great confidence in our results, we’re looking forward to comparing them with those from other experiments.”

“The potential impact on science is too large to draw immediate conclusions or attempt physics interpretations. My first reaction is that the neutrino is still surprising us with its mysteries.” said Ereditato. “Today’s seminar is intended to invite scrutiny from the broader particle physics community.”

Original Story Source: CERN Press Release. For Further Reading: Measurement of the neutrino velocity with the OPERA detector in the CNGS beam.

Read our previous article on this paper.

Breaking the Speed of Light

Particle Collider

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It’s been a tenet of the standard model of physics for over a century. The speed of light is a unwavering and unbreakable barrier, at least by any form of matter and energy we know of. Nothing in our Universe can travel faster than 299,792 km/s (186,282 miles per second), not even – as the term implies – light itself. It’s the universal constant, the “c” in Einstein’s E = mc2, a cosmic speed limit that can’t be broken.

That is, until now.

An international team of scientists at the Gran Sasso research facility outside of Rome announced today that they have clocked neutrinos traveling faster than the speed of light. The neutrinos, subatomic particles with very little mass, were contained within beams emitted from CERN 730 km (500 miles) away in Switzerland. Over a period of three years, 15,000 neutrino beams were fired from CERN at special detectors located deep underground at Gran Sasso. Where light would have made the trip in 2.4 thousandths of a second, the neutrinos made it there 60 nanoseconds faster – that’s 60 billionths of a second – a tiny difference to us but a huge difference to particle physicists!

The implications of such a discovery are staggering, as it would effectively undermine Einstein’s theory of relativity and force a rewrite of the Standard Model of physics.

The OPERA Neutrino Detector. Credit: LGNS.

“We are shocked,” said project spokesman and University of Bern physicist Antonio Ereditato.

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

Neutrinos are created naturally from the decay of radioactive materials and from reactions that occur inside stars. Neutrinos are constantly zipping through space and can pass through solid material easily with little discernible effect… as you’ve been reading this billions of neutrinos have already passed through you!

The experiment, called OPERA (Oscillation Project with Emulsion-tRacking Apparatus) is located in Italy’s Gran Sasso facility 1,400 meters (4,593 feet) underground and uses a complex array of electronics and photographic plates to detect the particle beams. Its subterranean location helps prevent experiment contamination from other sources of radiation, such as cosmic rays. Over 750 scientists from 22 countries around the world work there.

Ereditato is confident in the results as they have been consistently measured in over 16,000 events over the past two years. Still, other experiments are being planned elsewhere in an attempt to confirm these remarkable findings. If they are confirmed, we may be looking at a literal breakdown of the modern rules of physics as we know them!

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

A preprint of the OPERA results will be posted on the physics website ArXiv.org.

Read more on the Nature article here and on Reuters.com.

UPDATE: The OPERA team paper can be found here.

 

 

Anti-hydrogen Captured, Held For First Time

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Can warp drive be far behind? A paper published in this week’s edition of Nature reports that for the first time, antimatter atoms have been captured and held long enough to be studied by scientific instruments. Not only is this a science fiction dream come true, but in a very real way this could help us figure out what happened to all the antimatter that has vanished since the Big Bang, one of the biggest mysteries of the Universe. “We’re very excited about the fact that we can actually now trap antimatter atoms long enough to study their properties and see if they’re very different from matter,” said Makoto Fujiwara, a team member from ALPHA, an international collaboration at CERN.

Antimatter is produced in equal quantities with matter when energy is converted into mass. This happens in particle colliders like CERN and is believed to have happened during the Big Bang at the beginning of the universe.

“A good way to think of antimatter is a mirror image of normal matter,” said team spokesman Jeffrey Hangst, a physicist at Aarhus University in Denmark. “For some reason the universe is made of matter, we don’t know why that is, because you could in principle make a universe of antimatter.”

In order to study antimatter, scientists have to make it in a laboratory. The ALPHA collaboration at CERN has been able to make antihydrogen – the simplest antimatter atom – since 2002, producing it by mixing anti- protons and positrons to make a neutral anti-atom. “What is new is that we have managed to hold onto those atoms,” said Hangst, by keeping atoms of antihydrogen away from the walls of their container to prevent them from getting annihilated for nearly a tenth of a second.

The antihydrogen was held in an ion trap, with electromagnetic fields to trap them in a vacuum, and cooled to 9 Kelvin (-443.47 degrees Fahrenheit, -264.15 degrees Celsius). To actually see if they made any antihydrogen, they release a small amount and see if there is any annihilation between matter and antimatter.

The next step for the ALPHA collaboration is to conduct experiments on the trapped antimatter atoms, and the team is working on a way to find out what color light the antihydrogen shines when it is hit with microwaves, and seeing how that compares to the colors of hydrogen atoms.

CERN Press release

ALPHA collaboration

Nature article.

LHC Sets Record for Particle Collisions, Marks “New Territory” in Physics

Event display of a 7 TeV proton collision recorded by ATLAS. Credit: CERN

Physicists at the CERN research center collided sub-atomic particles in the Large Hadron Collider on Tuesday at the highest speeds ever achieved. “It’s a great day to be a particle physicist,” said CERN Director General Rolf Heuer. “A lot of people have waited a long time for this moment, but their patience and dedication is starting to pay dividends.” Already, the instruments in the LHC have recorded thousands of events, and at this writing, the LHC has had more than an hour of stable and colliding beams.

This is an attempt to create mini-versions of the Big Bang that led to the birth of the universe 13.7 billion years ago, providing new insights into the nature and evolution of matter in the early Universe.
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