Register by Sept. 5 for LHC start-up pajama party

Office of Communication Director Judy Jackson advertises Fermilab's upcoming Pajama Party

Celebrate the start up of the Large Hadron Collider at Fermilab's Pajama Party. At 1:30 a.m. on Wednesday, Sept. 10, Fermilab will host a pajama party at the LHC Remote Operations Center to watch the first beam circulate in the LHC. Breakfast will be served following the LHC start-up. You may wear pajamas. All employees must register by 5 p.m. on Friday, Sept. 5, to attend.

Fermilab physicists discover "doubly strange" particle

The DZero collaboration discovered the Omega-sub-b, a particle made of three quarks. The short-lived particle travels about a milimeter before it decays into lighter particles.

Physicists of the DZero experiment at the U.S. Department of Energy's Fermi National Accelerator Laboratory have discovered a new particle made of three quarks, the Omega-sub-b (Ω_b). The particle contains two strange quarks and a bottom quark (s-s-b). It is an exotic relative of the much more common proton and weighs about six times the proton mass.

The discovery of the doubly strange particle brings scientists a step closer to understanding exactly how quarks form matter and to completing the "periodic table of baryons." Baryons (derived from the Greek word "barys," meaning "heavy") are particles that contain three quarks, the basic building blocks of matter. The proton comprises two up quarks and a down quark (u-u-d).

Combing through almost 100 trillion collision events produced by the Tevatron particle collider at Fermilab, the DZero collaboration found 18 incidents in which the particles emerging from a proton-antiproton collision revealed the distinctive signature of the Omega-sub-b. Once produced, the Omega-sub-b travels about a millimeter before it disintegrates into lighter particles. Its decay, mediated by the weak force, occurs in about a trillionth of a second.

Theorists predicted the mass of the Omega-sub-b baryon to be in the range of 5.9 to 6.1 GeV/c². The DZero collaboration measured its mass to be 6.165 ± 0.016 GeV/c². The particle has the same electric charge as an electron and has spin J=1/2.

The Omega-sub-b is the latest and most exotic discovery of a new type of baryon containing a bottom quark at the Tevatron particle collider at Fermilab. Its discovery follows the observation of the Cascade-b-minus baryon (Ξ_b-), first observed by the DZero experiment in 2007, and two types of Sigma-sub-b baryons (Σ_b), discovered by the CDF experiment at Fermilab in 2006.

"The observation of the doubly strange b baryon is yet another triumph of the quark model," said DZero cospokesperson Dmitri Denisov, of Fermilab. "Our measurement of its mass, production and decay properties will help us to better understand the strong force that binds quarks together."

According to the quark model, invented in 1961 by theorists Murray Gell-Mann and Yuval Ne'eman as well as George Zweig, the four quarks, up, down, strange and bottom, can be arranged to form 20 different spin-1/2 baryons. Scientists now have observed 13 of these combinations.

"The measurement of the mass of the Omega-sub-b provides a great test of computer calculations using lattice quantum chromodynamics," said Fermilab theorist Andreas Kronfeld. "The discovery of this particle is an example of all the wonderful results pouring out of accelerator laboratories over the past few years."

Read the full release.

The Standard Model and beyond: new physics search

New physics
describes any discovery that goes beyond the Standard Model of particle interactions and the 12 elementary particles that combine to create other particles. The only elementary particle predicted by this theory and not yet found is the Higgs boson, thought to impart mass to all other particles. A discovery of any other elementary particle would fall into the category of new physics, including finding multiple Higgs boson particles of different masses.

Other new physics phenomena predicted include: extra dimensions of space; supersymmetry, the existence of a heavier, undiscovered superpartner for every known particle; a dark-matter particle that serves as an invisible type of gravity accounting for about 25 percent of the universe's mass and influencing the formation and motion of galaxies; quark-gluon plasma, created when nuclear material melts at temperatures reminiscent of the Big Bang; and new forces of nature.

New physics searches try to explain mass hierarchy of particle types, why 96 percent of the universe is not made up of matter but comprised of theorized dark energy and dark matter and the dominance of matter over antimatter.

Why we want to find new physics
Finding new physics would change our understanding of science and the universe and could lead to breakthroughs in research and technology as happened with the discovery of the Theory of Relativity and Quantum Mechanics.

The Standard Model is the current theory of the subatomic particles that make up all matter we see and feel and the forces of nature that determine the behavior of these particles. This serves as a guidebook of the building blocks of the universe.

The LHC and Tevatron both search for the Higgs boson. The Tevatron can only find the Higgs if it lies in a specific energy range. The LHC, with seven times the energy of the Tevatron, can search for the Higgs in all the energy ranges where theories predict the Higgs might reside. Both experiments also look for signs of new physics, including extra dimensions.