Particle Discovery Creates Buzz

It has been a long time since anew particle showed up and this may well be and surely must be a very lowprobability event.  My own ruminationssuggest that we are presently seeing the high energetic fraction of possibleparticles and that we could well have a wide range of possible particles todeal with.  We need to at least throw thedoor open.  It would be amusing todiscover many other particles hiding under the door mat.

We now have this presently uniqueobservation and we may wait a long time for a repetition.

At least particle physics isstill exciting.

Particle DiscoveryHas Physicists Abuzz

Clara Moskowitz, LiveScienceSenior Writer

Date: 06 April 2011Time: 03:17 PM ET

A proton-proton collision at the Large Hadron Collider particleaccelerator at CERN laboratory in Genevathat produced more than 100 charged particles. 

http://www.livescience.com/13594-physics-particle-discovery-fermilab.html

In a development physicists are calling "huge,""tantalizing" and "unexpected," researchers have measured asignal that could herald a new kind of particle or force of nature.

Yet the finding is not yet conclusive, and leaves many researchersskeptical.

The discovery comes from an atom smasher called the Tevatron at theFermilab physics laboratory in Batavia, Ill. Inside the acceleratorthere, particles are ramped up to near the speed of light as they race around a4 mile (6.3 km) ring. When two particles collide, they disintegrate into otherexotic particles in a powerful outpouring of energy. [WackyPhysics: The Coolest Little Particles in Nature]

Scientists analyzed thousands of these collisions, and found asuspicious pattern in about 250 more cases than predicted. In these instances,the products of the collision between a proton and itsantimatter partner,the antiproton, were different than expected.

Buzzing

"The whole physics world is buzzing with this result,"physicist David Kawall of the University of Massachusetts Amherst toldLiveScience.

The discovery, first reported in the NewYork Times, was announced online Tuesday (April 5) when the researchersposted a preview version of their research paper on the preprint site ArXiv.org.

"This is huge — an unexpected discovery which could completelytransform high-energy physics, and cosmology as well, as the two fields arejoined at the hip," astrophysicist Michael S. Turner, director of theKavli Institute for Cosmological Physics at The University of Chicago, wrote inan email to LiveScience. "But there is one big IF — if it holds up and isnot explained by standardmodel physics."

Many researchers echoed that caveat — the discovery could besignificant, but it's too soon to tell, because more data is required toconfirm that the Tevatron's pattern is more than just a statistical anomaly.

"The statistical significance of the signal is interesting, butnot compelling," said physicist Eugene W. Beier of the University of Pennsylvania."The experimenters need more data. If the signal does hold up at the fivestandard deviation level, it is an indication of something beyond the range ofwhat we expected."

The level of statistical significance in the data now is just overthree standard deviations, which means that the chance of it being a randomanomaly is less than 1 in 1,000. Thus, the finding is significant, and meritsinvestigation, but is not conclusive, researchers say. If enough furthermeasurements are made, and the pattern holds up to five standard deviations,more physicists would likely be convinced.

"I am not convinced," said Syracuse Universityphysicist Sheldon Stone. "It relies on a detailed estimate of thebackgrounds and small changes could wipe out the result."

Colliding matter and antimatter

The Tevatron has been colliding protons and antiprotons since the1980s, and has made many significant findings already, including the 1995discovery of the top quark, an exotic version of the fundamental particles thatmake up protons and neutrons.

"This tantalizing result from the CDF collaboration couldcertainly be game changing," said Gavin Salam, a physicist at the CERNresearch lab in Geneva, Switzerland. "If it isconfirmed, it would be the first time that a new particle was observed in acollider experiment since the top quark was discovered at Fermilab in1995."

In the new finding, scientists at the Tevatron's Collider Detector atFermilab (CDF) experiment found that the particle collisions produced ahigher-than-predicted incidence of a certain pattern of byproducts: one heavyparticle called a W boson, and two jets of lightweight particles with a totalenergy that was unexpected. 

The energy of the jets could indicate that they come from anever-before-seen subatomic particle, scientists say. One of the most avidlysought theoretical particles is the so-called Higgs boson, the particle thoughtto bestow mass on other particles. Yet the signal the Tevatron team found doesnot quite match what's expected for the Higgs.

"It would be nothing like a standard Higgs boson, as theproduction rate is far too high," said Rutgers Universityphysicist Matt Strassler. "Beyond that, it is hard to say; we simply don'thave enough information yet."

And because particles are tied to the forces of nature, the discoverycould even indicate a fundamental force in addition to the known four: gravity,electromagnetism, and the strong and weak nuclear forces.

"If this is in fact the first hint of new physics to be confirmedby other measurements with higher statistics, it would be very exciting,"said physicist Jamie Nagle of the Universityof Colorado, Boulder. "Exactly how excitingdepends on what new physics it turns out to be — which cannot be determinedfrom these results alone."

The finding could also be a vindication for the Tevatron, which isplanned to close in September 2011 for budget reasons. While it was once themost powerful particle accelerator on the planet, it has recently beensurpassed by the new LargeHadron Collider at CERN.

If the Tevatron's discovery represents a real event, and not a blip ofstatistics, it will likely also be seen in the LHC. Until then, many scientistssay they will reserve judgment.

For now, though, the excitement certainly continues.

"I have spent the better part of the day discussing the viabilityof these results and possible explanations with colleagues from around theworld," said Cornell University physicistCsaba Csaki. "If it indeed turns out to be the signal of a newparticle, it would be extremely important, potentially 'game-changing.' Howeverat this point I would be extremely cautious about declaring the discovery of anew particle. While the result should definitely be taken seriously, a lot morework has to be done before this can be accepted as a fact."

You can follow LiveScience senior writer Clara Moskowitz on Twitter @ClaraMoskowitz. For morescience news, follow LiveScience on twitter @livescience.