CERN LHC News & Discoveries

[PlanetFrnd]

Big things happening at CERN this year...

I thought I already posted something somewhere else about experimental findings at CERN that showed neutrinos moving faster than light (mid-Nov) and this week experimental data showed particle decay potentially of the elusive Higgs Boson... a theoretical "missing particle," if you will, which gives particles their mass... very cool stuff this year...

Higgs boson discovery:

http://www.scientificamerican.com/article.cfm?id=cern-physicists-find-hint-of-higgs-2011-12

CERN physicists find hint of Higgs boson
Tuesday, December 13, 2011

These red lines show how the LHC's Atlas experiment registered the arrival of four particles called muons. They could have been the byproducts of a short-lived Higgs boson--or they could have been more humdrum events. CERN's LHC particle accelerator will continue smashing protons into each other to spot the statistical significance that means the Higgs really has been found.
(Credit: CERN)

Researchers at the CERN particle accelerator have found "intriguing hints" of the Higgs boson, a moment of major progress in years of previously unfruitful searching for the elusive subatomic particle.

The search for the Higgs boson is the top priority of CERN's massive and expensive Large Hadron Collider near Geneva, Switzerland. Its Atlas experiment showed a statistically suspicious increase in activity that indicates the Higgs could be pinned down with a mass of 126 giga-electron-volts, and showing some important agreement, its independent CMS experiment found a possible result nearby at 124GeV.

"We observe an excess of events around mass of about 126 GeV," CERN physicist and Atlas leader Fabiola Gianotti said in slides presented today at a CERN seminar to physicists who applauded her results. That equates to about 212 quintillionths of a gram; by comparison, a proton is more than 100 times lighter with a mass of 0.938GeV...

http://www.economist.com/node/21541797

The Higgs boson
Fantasy turned reality
Those searching for the Higgs boson may at last have cornered their quarry

Dec 14th 2011 | from the print edition

WELL, they've found it. Possibly. Maybe. Pinning down physicists about whether they have actually discovered the Higgs boson is almost as hard as tracking down the elusive subatomic beast itself. Leon Lederman, a leading researcher in the field, once dubbed it the "goddamn" particle, because it has proved so hard to isolate. That name was changed by a sniffy editor to the "God" particle, and a legend was born. Headline writers loved it. Physicists loved the publicity. CERN, the world's biggest particle-physics laboratory, and the centre of the hunt for the Higgs, used that publicity to help keep the money flowing.

And this week it may all have paid off. On December 13th two of the researchers at CERN's headquarters in Geneva announced to a breathless world something that looks encouragingly Higgsy.

The Higgs boson, for those who have not been paying attention to the minutiae of particle physics over the past few years, is a theoretical construct dreamed up in 1964 by a British researcher, Peter Higgs (pictured above), and five other, less famous individuals. It is the last unobserved piece of the Standard Model, the most convincing explanation available for the way the universe works in all of its aspects except gravity (which is dealt with by the general theory of relativity).

The Standard Model (see table) includes familiar particles such as electrons and photons, and esoteric ones like the W and Z bosons, which carry something called the weak nuclear force. Most bosons are messenger particles that cement the others, known as fermions, together. They do so via electromagnetism and the weak and strong nuclear forces. The purpose of the Higgs boson, however, is different. It is to inculcate mass into those particles which weigh something. Without it, or something like it, some of the Standard Model's particles that actually do have mass (particularly the W and Z bosons) would be predicted to be massless. Without it, in other words, the Standard Model would not work.

The announcement, by Fabiola Gianotti and Guido Tonelli - the heads, respectively, of two experiments at CERN known as ATLAS and CMS - was that both of their machines have seen phenomena which look like traces of the Higgs...

And some background from 1999

http://www.scientificamerican.com/article.cfm?id=what-exactly-is-the-higgs

What exactly is the Higgs boson? Have physicists proved that it really exists?
October 21, 1999 | 20

Stephen Reucroft in the Elementary Particle Physics group at Northeastern University gives this introductory reply: "Over the past few decades, particle physicists have developed an elegant theoretical model (the Standard Model) that gives a framework for our current understanding of the fundamental particles and forces of nature. One major ingredient in this model is a hypothetical, ubiquitous quantum field that is supposed to be responsible for giving particles their masses (this field would answer the basic question of why particles have the masses they do--or indeed, why they have any mass at all). This field is called the Higgs field. As a consequence of wave-particle duality, all quantum fields have a fundamental particle associated with them. The particle associated with the Higgs field is called the Higgs boson...

 

[PlanetFrnd]

On the neutrino discoveries:

http://www.nytimes.com/2011/09/23/science/23speed.html?_r=1&ref=space

September 22, 2011
Tiny Neutrinos May Have Broken Cosmic Speed Limit

By DENNIS OVERBYE

Roll over, Einstein?

The physics world is abuzz with news that a group of European physicists plans to announce Friday that it has clocked a burst of subatomic particles known as neutrinos breaking the cosmic speed limit - the speed of light - that was set by Albert Einstein in 1905.

If true, it is a result that would change the world. But that "if" is enormous.

Even before the European physicists had presented their results - in a paper that appeared on the physics Web site arXiv.org on Thursday night and in a seminar at CERN, the European Center for Nuclear Research, on Friday - a chorus of physicists had risen up on blogs and elsewhere arguing that it was way too soon to give up on Einstein and that there was probably some experimental error. Incredible claims require incredible evidence.

"These guys have done their level best, but before throwing Einstein on the bonfire, you would like to see an independent experiment," said John Ellis, a CERN theorist who has published work on the speeds of the ghostly particles known as neutrinos.

According to scientists familiar with the paper, the neutrinos raced from a particle accelerator at CERN outside Geneva, where they were created, to a cavern underneath Gran Sasso in Italy, a distance of about 450 miles, about 60 nanoseconds faster than it would take a light beam. That amounts to a speed greater than light by about 0.0025 percent (2.5 parts in a hundred thousand)...

http://www.nytimes.com/2011/11/19/s...n-second-experiment-opera-scientists-say.html

November 18, 2011
Scientists Report Second Sighting of Faster-Than-Light Neutrinos

By DENNIS OVERBYE

Few scientists are betting against Einstein yet, but the phantom neutrinos of Opera are still eluding explanation.

Two months after scientists reported that they had clocked subatomic particles known as neutrinos going faster than the speed of light, to the astonishment and vocal disbelief of most of the world's physicists, the same group of scientists, known as Opera, said on Friday that it had performed a second experiment that confirmed its first results and eliminated one possible explanation for how the experiment could have gone wrong.

But the group admitted that many questions remain. "This is not the end of the story," said Antonio Ereditato of the University of Bern in Switzerland, the spokesman for the collaboration, explaining that physicists would not accept the result that neutrinos could go faster than light until other experiments had come up with the same conclusion. "We are convinced, but that is not enough in science," he said.

Other physicists said they remained skeptical that the universe was about to be overturned.

The speed of light was established as the cosmic speed limit, at least for ordinary matter in ordinary space, in 1905 by Albert Einstein?s theory of relativity (now known as special relativity), foreclosing the possibility of time travel into the past or of timely travel to other stars.

Neutrinos, though ghostly in many regards - they are able to traverse planets and walls of lead like light through a window, and to shape-shift from one of three varieties of the particle to another along the way - are part of the universe, and so there was no reason to expect that Einstein's stricture should not apply to them as well...

 

[Buckeye Maniac]

Correct me if I'm wrong, but didn't CERN recant their claims of a faster than light neutrino after discovering a mistake?

 

[PlanetFrnd]

Correct me if I'm wrong, but didn't CERN recant their claims of a faster than light neutrino after discovering a mistake?

Haven't seen that, but could be...

 

[Buckeye Maniac]

Haven't seen that, but could be...

Turns out it was another group claiming it's wrong:

GENEVA ? Scientists studying the same neutrino particles that colleagues say appear to have traveled faster than light rejected the startling finding this weekend, saying their tests had shown it must be wrong.
The September announcement of the faster-than-light finding, backed up last week after new studies, caused a furor in the scientific world, as it seemed to suggest that Albert Einstein's ideas on relativity, and much of modern physics, were based on a mistaken premise.

LINK






As you posted, CERN claims to have done it again.

 

[AKAK]

There are a number of questions about the result (obviously) and both the OPERA guys and others are trying to recreate them with some different measurement systems. I think right now the biggest issue is a possible issue with the GPS synchronzation as part of the timing measurement, so, they're trying to do it with fiber optics as well (in addition). And like the linked articel there, there are a number of questions as to why the neutrinos didn't "behave" as anticipated. I think they want to work out the timing issues first though.

 

[muffler dragon]

This is intellectual porn if I do say so myself.

 

[buckeyegrad]

Correct me if I'm wrong, but didn't CERN recant their claims of a faster than light neutrino after discovering a mistake?

My understanding, and it comes from a radio interview I heard with a Harvard physicist, is that the original paper published by CERN doubted their own findings, but they couldn't find a mistake in their design or measurements. The paper was asking the scientific community to look over their study for errors they may be missing.

 

[scooter1369]

I think CERN discovered the Higgs-Boson next week.

 

[AKAK]

Higgs Boson?

 

[PlanetFrnd]

Been away a while - Higgs was a nice birthday surprise :cheers:

http://www.economist.com/node/21558254

The Higgs boson
Science's great leap forward
After decades of searching, physicists have solved one of the mysteries of the universe

Jul 7th 2012 - from the print edition

HISTORICAL events recede in importance with every passing decade. Crises, political and financial, can be seen for the blips on the path of progress that they usually are. Even the horrors of war acquire a patina of unreality. The laws of physics, though, are eternal and universal. Elucidating them is one of the triumphs of mankind. And this week has seen just such a triumphant elucidation.

On July 4th physicists working in Geneva at CERN, the world?s biggest particle-physics laboratory, announced that they had found the Higgs boson (see article). Broadly, particle physics is to the universe what DNA is to life: the hidden principle underlying so much else. Like the uncovering of DNA?s structure by Francis Crick and James Watson in 1953, the discovery of the Higgs makes sense of what would otherwise be incomprehensible. Its significance is massive. Literally. Without the Higgs there would be no mass. And without mass, there would be no stars, no planets and no atoms. And certainly no human beings. Indeed, there would be no history. Massless particles are doomed by Einstein?s theory of relativity to travel at the speed of light. That means, for them, that the past, the present and the future are the same thing.

Deus et CERN

Such power to affect the whole universe has led some to dub the Higgs "the God particle". That, it is not. It does not explain creation itself. But it is nevertheless the most fundamental discovery in physics for decades...

http://www.economist.com/node/21558248

The Higgs boson
Gotcha!
The hunt for physics?s most elusive quarry is over

Jul 7th 2012 - from the print edition

"WE HAVE a discovery." Rolf Heuer, the director-general of CERN, was in no doubt. He left none of the wiggle-room with which physicists often hedge their announcements when he summed up the results of his organisation's search for the Higgs boson. These were presented in detail on July 4th by Joe Incandela and Fabiola Gianotti, the leaders of the two experiments that have been looking for the elusive particle. CMS, run by Dr Incandela, and ATLAS, run by Dr Gianotti, are fitted to the Large Hadron Collider (LHC), the principal piece of equipment at Europe's main particle-physics laboratory, near Geneva, which CERN runs. Both have found conclusive evidence for a particle of the right type and mass to be the Higgs. If it is not actually the Higgs, that will be the biggest upset in physics for a century.

It has taken five decades, billions of dollars and millions of man-hours. But, at long last, Peter Higgs, a British physicist (pictured above), and four other, less well-known individuals - Francois Englert, Gerald Guralnik, Tom Kibble and Carl Hagen - can crack open a bottle of champagne. They are the ones who, in 1964, plucked what has come to be known (unfairly in some eyes) as the Higgs boson from formulae they were working on to fix a niggle in quantum theory. Another co-originator, Robert Brout, died last year.

The discovery puts the finishing flourish on the Standard Model, the best explanation to date for how the universe works - except in the domain of gravity, which is governed by the general theory of relativity. The model comprises 17 particles. Of these, 12 are fermions such as quarks (which coalesce into neutrons and protons in atomic nuclei) and electrons (which whizz around those nuclei). They make up matter. A further four particles, known as gauge bosons, transmit forces and so allow fermions to interact: photons convey electromagnetism, which holds electrons in orbit around atoms; gluons link quarks into protons and neutrons via the strong nuclear force; W and Z bosons carry the weak nuclear force, which is responsible for certain types of radioactive decay. And then there is the Higgs...

http://www.economist.com/blogs/graphicdetail/2012/07/daily-chart-1

Daily chart
Worth the wait
Jul 4th 2012, 13:24 by The Economist online

A timeline of the Standard Model of particle physics
ON JULY 4th researchers at CERN, Europe's main particle-physics lab, confirmed their discovery of something that looks very much like the Higgs boson. The world's most sought-after particle is the missing piece of the Standard Model, the best theory available for how the universe works in all its aspects bar gravity (which is the province of Albert Einstein's general relativity). The model divides elementary particles into two classes. First, there are the fermions, a group comprising quarks (like those which make up protons and neutrons in atomic nuclei) and leptons (such as electrons that orbit these nuclei, and ghostly neutrinos). Then there are the bosons: gauge bosons, which carry forces of nature that allow the fermions to interact, and the Higgs boson, whose role is to endow the others with mass. The concept of the Higgs was introduced in 1964, so it has taken physicists 48 years to go from idea to observation. None of the model's 16 other particles was as elusive. Indeed, as our chart shows, the muon and the tau were discovered before anyone had predicted their existence. Both are leptons, heavier versions of the familiar electron, the first elementary particle to be observed, by J.J. Thomson, a Briton, in 1897. Though the notion of a unit of negative charge had been around since the 1830s, a firmer prediction was made in 1881 by a German scientist, Hermann von Helmholz. The positron, the electron's antimatter twin (not included in our chart, since in terms of the Standard Model, particles and their antiversions are two sides of a single coin) popped out of an equation in 1928; it popped up in an experiment four years later.

 

[PlanetFrnd]

I'm a junkie for this stuff:

http://www.economist.com/blogs/babbage/2012/12/higgs-boson

The Higgs boson
Double trouble
Dec 16th 2012, 13:34 by J.P.

AS DISCOVERIES go, that of the Higgs boson is as big as they get. Much of modern physics hinges on the particle, first predicted 48 years ago by Peter Higgs, a Briton, and independently by two other teams of theorists, and finally observed earlier this year at CERN, Europe's main particle-physics laboratory, outside Geneva (earning the seven leading experimenters a $3m prize earlier this week from a Russian internet mogul). Paradoxically, however, many boffins would rather Dr Higgs's prediction not be borne out to the letter. The latest results from ATLAS, one of the two experiments spearheading the Higgs hunt at CERN, offers the contrarians a glint of hope.

The reason the Higgs is imperative is that without it, or something like it, to give mass to other particles, the entire elaborate mathematical edifice erected over the past four decades to describe the most fundamental constituents of reality would topple. The reason many physicists would prefer it to differ from what Dr Higgs and the others postulated is that this would give them an inkling of where the successor to the Standard Model, as that venerable theory is known, might be hiding.

For all its explanatory power, the Standard Model leaves some big questions, like why the universe is made of matter, unanswered. Theorists have plenty of ideas which explain everything the model does, and more. But if observations conform precisely to its predictions, they have no way of telling which of these ideas reflects reality. For that, they need data at odds with the reigning theory.

On December 13th ATLAS obliged - sort of. An unstable beast, the Higgs cannot be observed directly. Instead, physicists look for telltale patterns left in the detector by longer-lived particles it decays into. Theory allows for a number of distinct decay modes, as the patterns are called. For example, the Higgs can break up into two photons or into two heavier particles called Z bosons, among other possibilities. By measuring the energy of these daughter particles, scientists can, by dint of Albert Einstein's famous equation E=mc2, work backwards to determine the mass of the parent. When ATLAS researchers did this with their latest batch of data, instead of both modes pointing to the same mass of around 125 giga-electron-volts (GeV), the esoteric unit used to weigh subatomic particles, they yielded two, slightly different masses: 123.5GeV for the Zs and 126.6Gev for the photons.

The difference is about three times the ATLAS detector's resolution of 1GeV or so. The odds that the result is down to chance are around one in 100, well below the exacting one-in-3.5m standard particle physicists have set themselves to claim a discovery, but enough to stoke speculation...

 

[AKAK]

You can't prove the Higgs doesn't exist!