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Something Weird this way comes

Posted: Fri Apr 08, 2011 1:01 pm
by neufer
http://www.universetoday.com/84688/particle-physicists-see-something-little-that-could-be-really-big/ wrote: Particle Physicists See Something Little That Could be Really Big
by Nancy Atkinson on April 7, 2011

<<Physicists from Fermilab have seen a “bump” in their data that could indicate a brand new particle unlike any ever seen before. If verified, this could re-write particle physics as we know it. “Essentially, the Tevatron has seen evidence for a new particle, 150 times mass of proton, that doesn’t behave like a standard Higgs particle,” said physicist Brian Cox on Twitter. “If this stands up to scrutiny and more data (there is not yet enough data for a “discovery”), then it is RIP Standard Model.”

“It was hard for us to not go crazy when we saw the results,” said Viviana Cavaliere from the University of Illinois (UIUC), one of the 500-member team working with the CDF particle detector at Fermi National Accelerator Laboratory in Batavia, Illinois, speaking on a webcast on April 6. “But for now, we need to stay focused on what we do know.”

The result comes from CDF’s (the Collider Detector at Fermilab) analysis of billions of collisions of protons and antiprotons produced by Fermilab’s Tevatron collider. In high energy collisions, subatomic particles can be detected that otherwise can’t be seen. Physicists try to identify the particles they see by studying the combinations of more-familiar particles into which they decay, while trying to find new particles, such as the theoretical Higgs Boson which is predicted by the Standard Model of particle physics.

The Standard Model contains a description of the elementary particles and forces inside atoms which make up everything around us. The model has been successful at making predictions that have been subsequently verified. There are sixteen named particles in the Standard Model, and the last particles discovered were the W and Z bosons in 1983, the top quark in 1995, and the tauon neutrino in 2000. But most physicists agree the Standard Model is probably not the final word in particle physics.

The researchers at Fermilab were searching for collisions that produced a W boson, which weighs about 87 times as much as a proton, as well as some other particles that disintegrate into two sprays of particles called “jets,” which are produced when a collision scatters out a particle called a quark.

Instead, they saw about 250 events which indicate a new particle weighing about 150 times as much as a proton, the team said at the webcast from Fermilab and in their paper on arXiv.

The researchers estimate the statistical chances of random jets or jet pairs from other sources producing a fake signal that strong at 1 in 1300.

The Standard Model does not predict anything like what was seen in the CDF experiment, and since this particle has not been seen before and appears to have some strange properties, the physicists want to verify and retest before claiming a discovery.

“If it is not a fluctuation, it is a new particle,” Cox said.

The Tevatron accelerator at Fermilab is scheduled to be shut down later this year, due to lack of funding and because of sentiments that it would be redundant to the Large Hadron Collider.>>
http://news.sciencemag.org/sciencenow/2011/04/fermilab-physicists-see-somethin.html?rss=1 wrote: Fermilab Physicists See Something Weird ...
by Adrian Cho on 6 April 2011, 5:50 PM | Permanent Link | 4 Comments

<<The particle physics world is abuzz with the news that researchers at the United States's sole particle physics lab may have spotted a weird particle unlike any seen before. That prospect is so tantalizing it garnered coverage in The New York Times. However, the experimenters who made the measurements caution that the supposed signal could also be a product of unidentified inaccuracies in their modeling of their incredibly complex particle detector. Physicists would also have trouble explaining how they missed the particle before.

"I'm kind of surprised that [The New York Times] wrote about it; it must have been a slow news day," says Robert Roser, co-spokesperson for the 500-member team working with the CDF particle detector at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, which made the observation. Still, he says, it's possible that the scientists have seen a new particle.

The result comes from CDF's analysis of billions of collisions of protons and antiprotons produced by Fermilab's Tevatron collider. According to Einstein's theory of relativity, energy equals mass, so those high-energy collisions can blast into fleeting existence massive subatomic particles not seen in the everyday world. Physicists then try to identify those particles by studying the combinations of more-familiar particles into which they decay.

In this case, experimenters searched for collisions that produced a particle called a W boson, which weighs about 87 times as much as a proton, and some other particle that disintegrates into two sprays of particles called "jets." A jet arises when a collision kicks out a particle called a quark. A quark cannot exist on its own, but must be bound to other quarks or an antiquark. So the energetic quark quickly rips more quarks and antiquarks out of the vacuum of empty space, and they instantaneously form particles called mesons, each containing a quark and an antiquark. From the energies and momenta of the two jets, researchers can infer the mass of the particle that produced them.

Shifting through their data, CDF researchers see about 250 events in which the jets seem to come from a particle weighing about 160 times as much as a proton, the team reports in a paper posted yesterday to the arXiv preprint server and in a talk today at Fermilab. The researchers estimate the statistical chances of random jets or jet pairs from other sources producing a fake signal that strong at one in 1300. "There's a lot of buzz here," says Joseph Lykken, a theorist at Fermilab who was not involved in the work. "I've gotten a lot of questions in that hallway."

So is it a done deal? Not quite, Lykken says. The analysis depends critically on physicists' understanding of jets, which are complex things. For example, the entire study grew out of an effort to spot events that produce two W bosons and one of the bosons produces a jet pair. So researcher must be absolutely sure that they haven't mistaken those two W events for ones containing a new particle. "The real question is how well do we understand that [background], not just theoretically, but in terms of how it will appear in the detector," Lykken says.

To have escaped notice until now, a new particle would also have to have some weird properties. For example, CDF researchers are searching for the long-sought Higgs boson, the key to physicists' understanding of mass, by looking for events in which it is produced along with a W boson and then decays into two jets specifically triggered by particles called bottom quarks. Those more-refined analyses have not seen the hypothetical new particle, so for some reason it must not decay into bottom quarks. Similarly, the hypothetical particle resembles the lighter W boson in its ability to decay into two jets. However, it apparently does not decay in the other ways that a W boson decays, or it would have been seen long ago.

Still, physicists say there's no reason to think that a wholly new type of particle won't have weird properties, Lykken says. And they expect the supposed signal to be confirmed or ruled out in short order. That's because CDF experimenters will soon analyze the other half of the data they've collected so far. More evidence will come from the Tevatron's other large particle detector, D0, which has generated a raw data set as big as CDF's. If the particle is really there, D0 should see it, too. If the signal is an artifact of the way CDF analyzes jets, then D0 would likely see nothing. "We understand that everybody is looking to us," says Dmitri Denisov, a physicist at Fermilab and co-spokesperson for the D0 team. "We hope that within a few weeks you'll be hearing from us.">>

Re: Something Weird this way comes

Posted: Sun Jul 24, 2011 3:44 pm
by neufer
http://www.bbc.co.uk/news/science-environment-14266358 wrote:
Higgs boson 'hints' also seen by US lab
By Paul Rincon Science reporter, BBC News, Grenoble : 24 July 2011

<<A US particle machine has seen possible hints of the Higgs boson, it has emerged, after reports this week of similar glimpses at Europe's Large Hadron Collider (LHC) laboratory. Researchers have been analysing data from the Tevatron machine near Chicago. The hints seen at the Tevatron are weaker than those reported at the LHC, but occur in the same "search region". Physicists have cautioned that these possible hints could disappear after further analysis. But researchers also say when the US and European results are taken together, they start to paint an "intriguing" picture. The results are being presented and discussed at the Europhysics conference in Grenoble, France.

The Tevatron and LHC machines work on similar basic principles, accelerating beams of particles to high energies around a tunnel before smashing them together. These collisions can generate new particles which can then be picked up by detectors built at the points where particle beams cross over. The LHC, which is housed in a 27km-long circular tunnel below the French-Swiss border, has two detectors looking for the Higgs: Atlas and CMS. Each is staffed by a different team of scientists. The Tevatron has a comparable arrangement, with two detectors called DZero and CDF.

On Friday, the Atlas and CMS teams reported finding what physicists call an "excess" of interesting particle events at a mass of between 140 and 145 gigaelectronvolts (GeV). The excess seen by the Atlas team has reached a 2.8 sigma level of certainty. A three-sigma result means there is roughly a one in 1,000 chance that the result is attributable to some statistical quirk in the data. Now, the US DZero and CDF experiments have also seen hints of something at about 140GeV.

Professor Stefan Soldner-Rembold, spokesperson for the DZero detector team, told BBC News: "There are some intriguing things going on around a mass of 140GeV. Professor Soldner-Rembold, from the University of Manchester in the UK, added: "There might be some picture emerging from the fog."

The Tevatron is also seeing the same type of interesting particle events as the LHC. In these events, one elementary particle "decays", or transforms, into another with a smaller mass. The interesting fluctuations seen at the Tevatron and the LHC are dominated by what might be the Higgs decaying into a pair of "W boson" particles. But the Tevatron results are currently at the one-sigma level of certainty - a lower level of statistical significance than those presented by the Atlas and CMS teams. Five-sigma is the level of certainty generally required for a formal discovery. At this significance level there is about a one in 1,000,000 chance that a bump in the data is just a fluke. However, says Professor Soldner-Rembold, the fact that teams working independently are now seeing similar phenomena point to an exciting possibility.

The existence of the Higgs boson was first proposed in the 1960s by Edinburgh University physicist Peter Higgs. The boson helps confer the property of mass on all other particles through their interaction with something called the Higgs field. The efforts put into finding the boson relate to its status as the last missing piece in the the Standard Model - the most widely accepted theory of particle physics. The Standard Model is a framework that explains how the known sub-atomic particles interact with each other. If the Higgs boson is not found, physicists would have to find some other mechanism to explain where particles get their mass. >>

Re: Something Weird this way comes

Posted: Sun Jul 24, 2011 4:19 pm
by bystander
Higgs Boson

Particle Physicists Report Possible Hints of Long-Sought Higgs Boson
Science NOW | Adrian Cho | 2011 July 22

Collider sees tantalizing hint of Higgs
Nature News | Geoff Brumfiel | 2011 July 22

Physicists find hints of a light Higgs boson in LHC data
ars technica | John Timmer | 2011 July 23

Tevatron experiments close in on favored Higgs mass range
Fermilab | 2011 July 21

The trivial Higgs boson: first evidences from LHC - P Cea, L Cosmai
Xi-sub-b Baryon

Fermilab experiment discovers a heavy relative of the neutron
Fermilab | 2011 July 20

Physicists Confirm Existence of New Particle
Wired Science | Duncan Geere, Wired UK | 2011 July 21

Tevatron produces neutron-like particle with strange, bottom quarks
ars technica | John Timmer | 2011 July 22

Xi baryons

Xi-sub-b Baryon

Posted: Sun Jul 24, 2011 5:40 pm
by neufer
bystander wrote:
Fermilab experiment discovers a heavy relative of the neutron

<<Scientists of the CDF collaboration at the Department of Energy’s Fermi National Accelerator Laboratory announced the observation of a new particle, the neutral Xi-sub-b. This particle contains three quarks: a strange quark, an up quark and a bottom quark (s-u-b). While its existence was predicted by the Standard Model, the observation of the neutral Xi-sub-b is significant because it strengthens our understanding of how quarks form matter. Fermilab physicist Pat Lukens, a member of the CDF collaboration, presented the discovery at Fermilab on Wednesday, July 20.

The neutral Xi-sub-b is the latest entry in the periodic table of baryons. Baryons are particles formed of three quarks, the most common examples being the proton (two up quarks and a down quark) and the neutron (two down quarks and an up quark). The neutral Xi-sub-b belongs to the family of bottom baryons, which are about six times heavier than the proton and neutron because they all contain a heavy bottom quark. The particles are produced only in high-energy collisions, and are rare and very difficult to observe.

Although Fermilab’s Tevatron particle collider is not a dedicated bottom quark factory, sophisticated particle detectors and trillions of proton-antiproton collisions have made it a haven for discovering and studying almost all of the known bottom baryons. Experiments at the Tevatron discovered the Sigma-sub-b baryons in 2006, observed the Xi-b-minus baryon in 2007, and found the Omega-sub-b in 2009. The lightest bottom baryon, the Lambda-sub-b, was discovered at CERN. Measuring the properties of all these particles allows scientists to test and improve models of how quarks interact at close distances via the strong nuclear force, as explained by the theory of quantum chromodynamics (QCD). Scientists at Fermilab and other DOE national laboratories use powerful computers to simulate quark interactions and understand the properties of particles comprised of quarks.

Once produced, the neutral Xi-sub-b travels a fraction of a millimeter before it decays into lighter particles. These particles then decay again into even lighter particles. Physicists rely on the details of this series of decays to identify the initial particle. The complex decay pattern of the neutral Xi-sub-b has made the observation of this particle significantly more challenging than that of its charged sibling (Xi-b-minus). Combing through almost 500 trillion proton-antiproton collisions produced by Fermilab's Tevatron particle collider, the CDF collaboration isolated 25 examples in which the particles emerging from a collision revealed the distinctive signature of the neutral Xi-sub-b. The analysis established the discovery at a level of 7 sigma. Scientists consider 5 sigma the threshold for discoveries.

CDF also re-observed the already known charged version of the neutral Xi-sub-b in a never before observed decay, which served as an independent cross-check of the analysis. The newly analyzed data samples offer possibilities for further discoveries.>>

Re: Something Weird this way comes

Posted: Mon Jul 25, 2011 2:40 pm
by neufer
http://en.wikipedia.org/wiki/Higgs_boson wrote: <<As of May 2011, the Higgs boson has yet to be confirmed experimentally, despite large efforts invested in accelerator experiments at CERN and Fermilab. In April 2011, there were suggestions in the media that evidence for the Higgs boson might have been discovered at the Large Hadron Collider (LHC) in Geneva, Switzerland. however these had been debunked by mid May. In regard to these rumors Jon Butterworth, a member of the High Energy Physics group on the Atlas experiment, stated they were not a hoax, but were based on unofficial, unreviewed results and that the scientific process requires prudence before making any conclusion.

Prior to the year 2000, the data gathered at the LEP collider at CERN allowed an experimental lower bound to be set for the mass of the Standard Model Higgs boson of 114.4 GeV/c2 at 95% confidence level. The same experiment has produced a small number of events that could be interpreted as resulting from Higgs bosons with mass just above said cutoff—around 115 GeV—but the number of events was insufficient to draw definite conclusions. The LEP was shut down in 2000 due to construction of its successor, the Large Hadron Collider (LHC) which is expected to be able to confirm or reject the existence of the Higgs boson. Full operational mode was delayed until mid-November 2009, because of a serious fault discovered with a number of magnets during the calibration and startup phase.

At the Fermilab Tevatron, there are ongoing experiments searching for the Higgs boson. As of July 2010, combined data from CDF and DØ experiments at the Tevatron were sufficient to exclude the Higgs boson in the range between 158 GeV/c2 and 175 GeV/c2 at the 95% confidence level. Further analysis of the same data, as of March 2011, have since extended the excluded region to the range between 156 GeV/c2 and 183 GeV/c2, at the 90% confidence level. Data collection and analysis in search of Higgs are intensifying since March 30, 2010 when the LHC began operating at 3.5 TeV and is rapidly approaching in its design range of 7 TeV, well above that at which detection should occur.

It may be possible to estimate the mass of the Higgs boson indirectly. In the Standard Model, the Higgs boson has a number of indirect effects; most notably, Higgs loops result in tiny corrections to masses of W and Z bosons. Precision measurements of electroweak parameters, such as the Fermi constant and masses of W/Z bosons, can be used to constrain the mass of the Higgs. As of 2006, measurements of electroweak observables allowed the exclusion of a Standard Model Higgs boson having a mass greater than 285 GeV/c2 at 95% CL, and estimated its mass to be 129+74−49 GeV/c2 (the central value corresponds to approximately 138 proton masses). As of August 2009, the Standard Model Higgs boson is excluded by electroweak measurements above 186 GeV at 95% CL. However, it should be noted that these indirect constraints make the assumption that the Standard Model is correct. One may still discover a Higgs boson above 186 GeV if it is accompanied by other particles between Standard Model and GUT scales.

Media have speculated that there already exists potential evidence, but to date no such evidence has convinced the physics community.

In a 2009 preprint, it was suggested (and reported under headlines such as Higgs could reveal itself in Dark-Matter collisions) that the Higgs boson might not only interact with the above-mentioned particles of the Standard model of particle physics, but also with the mysterious WIMPs ("weakly interacting massive particles") of the Dark matter, playing a most-important role in recent astrophysics. In this case, it is natural to augment the above Feynman diagrams by terms representing such an interaction. In principle, a relation between the Higgs particle and the Dark matter would be "not unexpected", since, (i), the Higgs field does not directly couple to the quanta of light (i.e. the photons), while at the same time, (ii), it generates mass. However, "dark matter" is a metonym for the discrepancy between the apparent observed mass of the universe and that given by the Standard Model and is not a component of any known theory of physics. Consequently, the usefulness of this conjecture is limited.

Barring discovery during current intensive efforts, it may be sometime after the end of the current physics fill at the LHC in 2011 and some further months or years of analysis of the collected data before scientists can confidently believe that the Higgs boson does or does not exist. Nonetheless, the LHC detected possible signs of the particle in July 2011, a finding repeated shortly thereafter by researchers at the Tevatron. They reported "interesting particle events at a mass of between 140 and 145 GeV".>>
http://www.bbc.co.uk/news/science-environment-14266358 wrote:
Higgs boson 'hints' also seen by US lab
By Paul Rincon Science reporter, BBC News, Grenoble : 24 July 2011

<<On Friday, the [Fermilab Tevatron] Atlas and CMS teams reported finding what physicists call an "excess" of interesting particle events at a mass of between 140 and 145 gigaelectronvolts (GeV). The excess seen by the Atlas team has reached a 2.8 sigma level of certainty. A three-sigma result means there is roughly a one in 1,000 chance that the result is attributable to some statistical quirk in the data. Now, the US DZero and CDF experiments have also seen hints of something at about 140GeV. Professor Stefan Soldner-Rembold, spokesperson for the DZero detector team, told BBC News: "There are some intriguing things going on around a mass of 140GeV. Professor Soldner-Rembold, from the University of Manchester in the UK, added: "There might be some picture emerging from the fog." >>
http://www.universetoday.com/84688/particle-physicists-see-something-little-that-could-be-really-big/ wrote: Particle Physicists See Something Little
That Could be Really Big
by Nancy Atkinson on April 7, 2011

<<Physicists from Fermilab have seen a “bump” in their data that could indicate a brand new particle unlike any ever seen before. If verified, this could re-write particle physics as we know it. “Essentially, the Tevatron has seen evidence for a new particle, 150 times mass of proton, that doesn’t behave like a standard Higgs particle,” said physicist Brian Cox on Twitter. “If this stands up to scrutiny and more data (there is not yet enough data for a “discovery”), then it is RIP Standard Model.” “It was hard for us to not go crazy when we saw the results,” said Viviana Cavaliere from the University of Illinois (UIUC), one of the 500-member team working with the CDF particle detector at Fermi National Accelerator Laboratory in Batavia, Illinois, speaking on a webcast on April 6. “But for now, we need to stay focused on what we do know.”>>

Re: Something Weird this way comes

Posted: Mon Jul 25, 2011 8:34 pm
by bystander
Asymmetric quarks defy standard model of physics
Nature News | Ron Cowen | 2011 July 23
Particle collisions hint at existence of undiscovered gluon.

Newly released observations of the top quark — the heaviest of all known fundamental particles — could topple the standard model of particle physics. Data from collisions at the Tevatron particle accelerator at Fermilab in Batavia, Illinois, hint that some of the top quark's interactions are governed by an as-yet unknown force, communicated by a hypothetical particle called the top gluon. The standard model does not allow for such a force or particle.
Hint of Higgs, but little more
Nature News | Geoff Brumfiel | 2011 July 25
No signs of exotic new physics have yet emerged from Europe's giant particle accelerator.

When its experiments started in earnest earlier this year, many scientists hoped that the world's most powerful collider would turn up new particles, additional dimensions and perhaps even a small black hole or two. But beyond a handful of unusual events, the latest data from the Large Hadron Collider (LHC) are frustratingly ordinary.
Physicists closing in on 'God particle' (update)
PhysOrg | AFP | 2011 July 25
Experiments at the world's biggest atom smasher have yielded tantalising hints that a long-sought sub-atomic particle truly exists, with final proof likely by late 2012, physicists said Monday.

"We know everything about the Higgs boson except whether it exists," said Rolf Heuer, director general of the European Organisation for Nuclear Research (CERN).

"We can settle this Shakespearean question -- to be or not to be -- by the end of next year," he told journalists at a webcast press conference at CERN headquarters in Geneva.

Researchers at the US Department of Energy's Fermilab, meanwhile, also reported telltale signs of the elusive particle, heating up a longstanding rivalry between the two high-energy physics laboratories.
Should we worry about what the LHC is not finding?
New Scientist | Richard Webb | 2011 July 25
The Higgs boson is still missing – but perhaps we should be more worried about what else the Large Hadron Collider hasn't found yet.

That's the main message to come out of a conference in Grenoble, France, this week, where physicists have gathered to chew over the first results from the world's most muscular particle smasher, sited at CERN near Geneva, Switzerland.

Finding the Higgs would complete the "standard model", our best stab yet at explaining the fundamental particles and forces of nature. But we already know that some weighty questions, such as the relationship between the strengths of different forces in the cosmos, or the nature of the dark matter thought to make up about three-quarters of its mass, lie beyond the standard model's scope. To answer these questions, physicists look to a grander construction known as supersymmetry.

Supersymmetry proposes that every particle predicted by the standard model has a meatier cousin that turns up only at extremely high energies. But the LHC has not found any such super-particles. "Squarks" and "gluinos", partners of the standard-model quarks and gluons, have been ruled out at energies up to 1 teraelectronvolts (TeV), according to an analysis of the LHC's first year of collisions.

No simple models

That is just the range in which the simplest family of supersymmetric models predicts these particles should be found. More energies and more complex models remain to be explored, but "the air is getting thin for supersymmetry", says Guido Tonelli of the LHC's CMS collaboration. At the same time, there is no sign yet of gravitons – particles that transmit gravity and are essential for a quantum theory of the force – below an energy of 2 TeV.

The missing particles leave some physicists wondering whether they have been asking the right questions up to now. But Rolf-Dieter Heuer, CERN's director general, counsels against hasty conclusions. With the machine still ramping up to full power, the LHC has produced just one-thousandth of the data it eventually should deliver. "Something will come," he says. "We just have to be patient."

In the case of the Higgs boson, at least, he's confident that something will come sooner rather than later. The LHC has already found the first tantalising glimpses of what might turn out to be this elusive particle, but more findings are needed to confirm or deny its existence. "We will have answered the Higgs's Shakespeare question – to be or not to be – by the end of next year," Heuer predicts.
Sometimes You Feel Like A Quark… And Sometimes You Don’t
Universe Today | Tammy Plotner | 2011 July 25

Hint of Higgs Boson? 'God Particle' Buzz Rises
Live Science | Stephanie Pappas | 2011 July 25

Physicists excited by hints of Higgs boson existence
PhysOrg | University of Birmingham | 2011 July 26

Flurry of New Results Narrow Range for Higgs
Discovery News | Jennifer Ouellette | 2011 July 26

Re: Something Weird this way comes

Posted: Tue Jul 26, 2011 7:13 pm
by bystander
Don't have all the information? In the quantum world, that doesn't matter
PhysOrg | Miranda Marquit | 2011 July 26
When it comes to the rules of the quantum world, it seems that almost everything goes against intuition. In the case of the way ignorance of the whole implies ignorance of at least one of its parts, the situation seems to be counterintuitive. "When viewed in a classical sense, you would be inclined to think that a strong ignorance of the whole has to be accompanied by significant ignorance of at least one of its parts," Stephanie Wehner tells PhysOrg.com. "However, this conjecture turns out to be false in quantum theory."

Wehner is a scientist at the National University of Singapore. She worked with Thomas Vidick at the University of California at Berkeley to examine the role of ignorance in quantum theory. Their work can be read in Physical Review Letters: “Does Ignorance of the Whole Imply Ignorance of the Parts? Large Violations of Noncontextuality in Quantum Theory.”

“Originally, we were motivated to study this problem from a cryptographic perspective,” Wehner explains. “However, we soon found that our exploration had implications for understanding the fundamentals of how quantum states work.”

Wehner and Vidick set out to see about exposing ignorance in cases of quantum communication. “Our problem can most easily be described by an example.” Wehner says. “Let’s say that you study a book that has two pages: one and two. You are going to sit an exam in this class, and you only had a small amount of time to study. You don’t know everything that is on page one and page two. Can I point to a page that you don’t know, thereby exposing your ignorance? Classically, this is indeed true: For example, if you only know the information on page one, I can point to page two and expose your ignorance. I can catch you.”

Classically, this scenario makes sense. Ignorance of the whole does imply ignorance about at least one of the parts. However, in the quantum world, it doesn’t work this way. “Quantumly, there is no way for me to expose your ignorance in this way. If I challenge you, you can guess the information – even if you don’t know it all – almost perfectly. It’s very counterintuitive.”

Wehner points out that the result has some strong implications for our understanding of the quantum world. “We haven’t really fully explored this effect yet. There are many weird quantum effects we still know little about, but this one is particularly intriguing as it deals with the basic question of how knowledge itself behaves in a quantum world.”

She goes on to point out that this research says something about fundamental differences in classical versus quantum knowledge. “It really makes a difference if the memory you have is classical or quantum. We are merely at the beginning of understanding these differences.”

Wehner says that she is planning to look more closely at the structure of quantum states. “Our example demonstrates that this effect can be rather dramatic. But does it always have to be this way? And, how do we tell?”

Additionally, Wehner would like to be able to design an experiment that would show this effect, since she and Vidick approached it theoretically. “In the end,” she admits, “our paper probably raises more questions than it answers. But it offers a good place to start, and a good beginning towards a deeper understanding of what distinguishes quantum from classical knowledge.”

Does Ignorance of the Whole Imply Ignorance of the Parts?
Large Violations of Noncontextuality in Quantum Theory
- Thomas Vidick, Stephanie Wehner

Calamities of Nature: The Higgs Boson (2011 July 27)

Posted: Wed Jul 27, 2011 4:47 am
by bystander

Re: Something Weird this way comes

Posted: Wed Jul 27, 2011 5:03 am
by Beyond
:lol: Isn't that the way it is with just about everything :?:

The first cartoon, that is, not the second one you added after i posted.

Caltech: A Hint of Higgs: An Update from the LHC

Posted: Tue Aug 16, 2011 3:09 am
by bystander
A Hint of Higgs: An Update from the LHC
California Institute of Technology | Marcus Woo | 2011 Aug 15
The physics world was abuzz with some tantalizing news a couple of weeks ago. At a meeting of the European Physical Society in Grenoble, France, physicists—including some from Caltech—announced that the latest data from the Large Hadron Collider (LHC) might hint at the existence of the ever-elusive Higgs boson.

According to the Standard Model, the remarkably successful theory of how all the fundamental particles interact, the Higgs boson is responsible for endowing every other particle with mass. And as the last remaining particle pr edicted by the Standard Model yet to be detected, its discovery is one of the chief goals of the LHC, the most powerful particle accelerator on Earth and perhaps the most complex scientific endeavor ever attempted.

Sitting underground near Geneva, Switzerland, the LHC accelerates protons around a ring almost five miles wide to nearly the speed of light, producing two proton beams that careen toward each other. Most of the protons just keep on going past each other, but a small fraction of them collide, creating other particles in the process. But these particles are fleeting, decaying into lighter particles before they can be detected. The challenge for physicists is to pick out hints of new, exotic physics from the flurry of newly minted particles. By sifting through the data, they hope to tease out signs that some of these particles are Higgs bosons.

The LHC is equipped with several detectors, but the ones that are the largest and are going after the Higgs are called ATLAS (A Toroidal LHC Apparatus) and the Compact Muon Solenoid (CMS); Caltech plays a prominent role in the latter. Both experiments recently reported what physicists are calling "excess events." That is, the LHC appears to have created slightly more events than would be expected if the Higgs does not exist. The bump occurred in the region between 130 and 150 gigaelectron volts (GeV—a unit of energy that is also a unit of mass, via E = mc2, where the speed of light, c, is set to a value of one), which is the expected mass range of the Higgs. But the data are not yet statistically significant enough to be called a definite signal, let alone a discovery of the Higgs particle, says Harvey Newman, professor of physics.

There are two possible explanations for these results, he says. The bump in the data could just be background events due to some unknown source or it could be the first signs of the Higgs. "One could speculate that it's an unusual statistical fluctuation," he says. "But I don't think so."

The LHC is now operating with 7 teraelectron volts (TeV, a thousand times higher than a GeV) of energy at the center of mass between the two proton beams, and may increase to 8 TeV next year (the maximum energy is 14 TeV, which will be reached by 2014).

Physicists will continue to ramp up the LHC, boosting it to higher energies and increasing the number of collisions to improve the chances of producing Higgs bosons. With several times more particle interactions, the physicists are continuing to close in on the Higgs, as well as other new particles and interactions. There's a chance that by the end of next year, they may determine, once and for all, whether the Higgs exists.

Searching for SUSY

If it turns out that the Higgs does not exist, then physicists will have to do some serious rethinking about the Standard Model. "But even if the Higgs exists, the Standard Model still has fundamental problems," Newman says. For example, the theory is not self-consistent. "The most natural way to solve these problems," he says, "is with supersymmetry."

Evidence for supersymmetry, abbreviated SUSY ("soosie"), is also something that physicists had anticipated at the LHC. The theory proposes that each fundamental particle has a supersymmetric partner—for example, a quark's partner is called a "squark." There are many versions of the theory, from simple toy models to subtler ones. So far, however, the LHC hasn't detected any signs of supersymmetry. "Many of the models we're excluding are toy models," says Maria Spiropulu, an associate professor of physics. So even though people might be disappointed, it's way too early to rule out the theory. "Some people get depressed that SUSY is being excluded. But it's quite the opposite—we're confirming that nature is much more subtle than what the obvious thing would be."

Caltech at the LHC

Spiropulu and Newman, who are now at the LHC working on the latest data run, lead the Caltech team of 40 physicists, students, and engineers that's part of the CMS collaboration. Spiropulu, who joined the faculty in 2008, is an expert on devising ways to discover exotic phenomena beyond the Standard Model, such as theories of supersymmetry that predict particles of dark matter, the mysterious stuff that makes up almost a quarter of the universe.

When Newman arrived at Caltech in the 1980s, he did a lot of the groundwork in designing the crystal detectors that are now used in CMS. He also developed the worldwide grid of networks and data centers that stores and processes the flood of data coming from the LHC. With the LHC generating gigabytes of data per second, no single site can hold all the information, so the data is handled in a distributed fashion at hundreds of sites throughout the world, including Caltech’s Center for Advanced Computing Research, where the first university-based center for LHC data analysis was invented. Newman’s team also runs the transatlantic network that links the LHC to the United States, allowing data to flow between Europe and North America. His team, together with Steven Low, professor of computer science and electrical engineering, developed the state-of-the-art applications for transferring data over long distances, enabling terabytes of data to stream between sites at speeds of up to the 100 gigabits per second. Newman and engineer Philippe Galvez also developed a system called Enabling Virtual Organizations, an internet-based tool that helps physicists and scientists from other fields communicate and collaborate from anywhere in the world.

According to Newman and Spiropulu, the Caltech team consists of experts in everything from the detector and data analysis to how new phenomena might manifest themselves at the LHC. Because the group is involved in so many aspects of CMS, Caltech is making a particularly significant contribution, Spiropulu says. "We are one of the leading groups in the U.S.—and I would say also in the entire CMS collaboration."

Undergraduates are also a critical part of the team. In the last two years, there have been a total of 24 students from the Summer Undergraduate Research Fellowships (SURF) and Minority Undergraduate Research Fellowships (MURF) programs, as well as from programs at CERN (the European Organization for Nuclear Research, the site of the LHC). This year, four SURF students are spending their summer at the LHC. "Caltech students can really 'do things' from an early age—at a level one rarely sees elsewhere," Newman says.

Re: Caltech: A Hint of Higgs: An Update from the LHC

Posted: Tue Aug 16, 2011 3:43 am
by neufer
bystander wrote:A Hint of Higgs: An Update from the LHC
California Institute of Technology | Marcus Woo | 2011 Aug 15
Click to play embedded YouTube video.
Searching for SUSY

If it turns out that the Higgs does not exist, then physicists will have to do some serious rethinking about the Standard Model. "But even if the Higgs exists, the Standard Model still has fundamental problems," Newman says. For example, the theory is not self-consistent. "The most natural way to solve these problems," he says, "is with supersymmetry." Evidence for supersymmetry, abbreviated SUSY ("soosie"), is also something that physicists had anticipated at the LHC. The theory proposes that each fundamental particle has a supersymmetric partner—for example, a quark's partner is called a "squark." There are many versions of the theory, from simple toy models to subtler ones. So far, however, the LHC hasn't detected any signs of supersymmetry. "Many of the models we're excluding are toy models," says Maria Spiropulu, an associate professor of physics. So even though people might be disappointed, it's way too early to rule out the theory. "Some people get depressed that SUSY is being excluded. But it's quite the opposite—we're confirming that nature is much more subtle than what the obvious thing would be."

CERN: ATLAS & CMS experiments present Higgs search status

Posted: Wed Dec 14, 2011 1:14 am
by bystander
ATLAS and CMS experiments present Higgs search status
CERN Press Release | 2011 Dec 13
In a seminar held at CERN today, the ATLAS and CMS experiments presented the status of their searches for the Standard Model Higgs boson. Their results are based on the analysis of considerably more data than those presented at the summer conferences, sufficient to make significant progress in the search for the Higgs boson, but not enough to make any conclusive statement on the existence or non-existence of the elusive Higgs. The main conclusion is that the Standard Model Higgs boson, if it exists, is most likely to have a mass constrained to the range 116-130 GeV by the ATLAS experiment, and 115-127 GeV by CMS. Tantalising hints have been seen by both experiments in this mass region, but these are not yet strong enough to claim a discovery.

Higgs bosons, if they exist, are very short lived and can decay in many different ways. Discovery relies on observing the particles they decay into rather than the Higgs itself. Both ATLAS and CMS have analysed several decay channels, and the experiments see small excesses in the low mass region that has not yet been excluded.

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. It's far too early to say whether ATLAS and CMS have discovered the Higgs boson, but these updated results are generating a lot of interest in the particle physics community.

"We have restricted the most likely mass region for the Higgs boson to 116-130 GeV, and over the last few weeks we have started to see an intriguing excess of events in the mass range around 125 GeV," explained ATLAS experiment spokesperson Fabiola Gianotti."This excess may be due to a fluctuation, but it could also be something more interesting. We cannot conclude anything at this stage. We need more study and more data. Given the outstanding performance of the LHC this year, we will not need to wait long for enough data and can look forward to resolving this puzzle in 2012."

"We cannot exclude the presence of the Standard Model Higgs between 115 and 127 GeV because of a modest excess of events in this mass region that appears, quite consistently, in five independent channels," explained CMS experiment Spokesperson, Guido Tonelli. "The excess is most compatible with a Standard Model Higgs in the vicinity of 124 GeV and below but the statistical significance is not large enough to say anything conclusive. As of today what we see is consistent either with a background fluctuation or with the presence of the boson. Refined analyses and additional data delivered in 2012 by this magnificent machine will definitely give an answer."

Over the coming months, both experiments will be further refining their analyses in time for the winter particle physics conferences in March. However, a definitive statement on the existence or non-existence of the Higgs will require more data, and is not likely until later in 2012.

The Standard Model is the theory that physicists use to describe the behaviour of fundamental particles and the forces that act between them. It describes the ordinary matter from which we, and everything visible in the Universe, are made extremely well. Nevertheless, the Standard Model does not describe the 96% of the Universe that is invisible. One of the main goals of the LHC research programme is to go beyond the Standard Model, and the Higgs boson could be the key.

A Standard Model Higgs boson would confirm a theory first put forward in the 1960s, but there are other possible forms the Higgs boson could take, linked to theories that go beyond the Standard Model. A Standard Model Higgs could still point the way to new physics, through subtleties in its behaviour that would only emerge after studying a large number of Higgs particle decays. A non-Standard Model Higgs, currently beyond the reach of the LHC experiments with data so far recorded, would immediately open the door to new physics, whereas the absence of a Standard Model Higgs would point strongly to new physics at the LHC's full design energy, set to be achieved after 2014. Whether ATLAS and CMS show over the coming months that the Standard Model Higgs boson exists or not, the LHC programme is opening the way to new physics.

Further Information:

ATLAS: http://www.atlas.ch/news/2011/status-re ... -2011.html
CMS: http://cms.web.cern.ch/news/cms-search- ... 0-and-2011

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ATLAS and CMS experiments present Higgs search status
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Re: Something Weird this way comes

Posted: Wed Feb 15, 2012 1:44 am
by bystander
Turning up the heat to find the Higgs and other new physics
Science & Technology Facilities Council | 2012 Feb 13
CERN has announced (13 February 2012) that the Large Hadron Collider (LHC) will run with a beam energy of 4 TeV this year. This is 0.5 TeV higher than in 2010 and 2011.

The LHC's excellent performance in 2010 and 2011 has brought tantalising hints of new physics, with scientists on two of the LHC's four experiments now focussed on a window of just 16GeV in which the Higgs boson can exist.

By increasing the beam energy in 2012, the aim is to deliver as much data as possible before the LHC goes into a long shutdown in November 2012 to prepare for higher energy running. This additional data will enable scientists to either confirm that the Higgs boson exists or to rule out the existence of a Standard Model Higgs. The data target for 2012 is 15 inverse femtobarns for ATLAS and CMS, the two experiments that looking for evidence of the Higgs boson. This is a factor of three higher than in 2011. The additional beam energy and data will also benefit the ALICE and LHCb experiments as they increase our understanding of quark-gluon plasmas and antimatter.

The LHC is due to resume operating in March after its annual winter break, and run through to November. There will then be a long technical stop of around 20 months, with the LHC restarting close to its full design energy late in 2014 and operating for physics at the new high energy in early 2015.

Further information is available on the CERN website.

LHC to Crank Up Collision Energies for 2012
Discovery News | Ian O'Neill | 2012 Feb 14