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Physicists pore over data hinting at mystery particle

March 30, 2005
Courtesy of the U.S. Dept. of Energy
and World Science staff

A new sub­a­tom­ic par­t­i­cle may be found, if in­tri­guing new da­ta from the Fer­mi Na­t­ional Ac­cel­er­a­tor Lab­o­r­a­to­ry in Bat­avia, Ill., is con­firmed, phys­i­cists say.

The par­t­i­cle is not part of the “s­tan­dard mod­el” of phys­ics that forms the gen­er­ally ac­cept­ed pic­ture of the bas­ic un­its of mat­ter and their in­ter­ac­tions. As such, the find­ing could up­end the stand­ard mod­el, some phys­i­cists said.

As it stands, re­search­ers re­ported, the da­ta in­di­cate that there is only a one in 1,375 chance that the find­ings are a sta­tis­ti­cal fluke. The sci­en­tists said they plan to re­peat the ex­pe­ri­ments with at least twice as much da­ta in or­der to get a bet­ter sense of wheth­er they have dis­cov­ered some­thing.

It’s not the much-an­ti­cipated “Higgs Boson,” a hy­po­thet­i­cal par­t­i­cle that would help com­plete the Stand­ard Mod­el, re­search­ers said, at least not in its tra­di­tion­al form. The Higgs would ex­plain why oth­er par­t­i­cles have mass or weight.

The find­ings come from an in­terna­t­ional col­la­bora­t­ion of sci­en­tists work­ing at the par­t­i­cle col­lider in Ba­ta­via, Ill. Mem­bers of the Col­lider De­tec­tor at Fer­milab, or CDF, col­la­bora­t­ion proj­ect were smash­ing to­geth­er pro­tons, sub­a­tom­ic par­t­i­cles that sit at the cores of at­oms, and an­ti­pro­tons, ex­ot­ic par­t­i­cles that are like pro­tons but with op­po­site elec­tri­cal charge.

An un­usu­ally high num­ber of col­li­sions re­sulted in a spe­cif­ic set of byprod­ucts, the in­ves­ti­ga­tors found. These byprod­ucts con­sisted of a par­t­i­cle known as a W bos­on, along with two hadronic jets, beams of par­t­i­cles. Calculations show these col­li­sion prod­ucts sug­gest that after the collision there briefly ap­peared a new par­t­i­cle es­ti­mat­ed to weigh about 140 GeV/c², about half­way be­tween the weight of an at­om of sil­ver and that of an at­om of gold.

The re­sult has been sub­mit­ted to the re­search jour­nal Phys­i­cal Re­view Let­ters. Re­search­ers at the Large Had­ron Col­lider, the world’s larg­est par­t­i­cle smash­er, out­side of Ge­ne­va, Switz­er­land, are ex­pected to al­so check their da­ta for sig­nals of the par­t­i­cle.

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A new subatomic particle may be found, if intriguing new data from the Fermi National Accelerator Laboratory is confirmed, physicists say. The particle is not part of the “standard model” of physics that forms the generally accepted picture of the basic units of matter and their interactions. As such, the finding could upend the standard model, some physicists said. As it stands, researchers reported, the data indicate that there is only a one in 1,375 chance that the findings are a statistical fluke. The scientists said they plan to repeat the experiments with at least twice as much data in order to get a better sense of whether they have discovered something. It’s not the much-anticipated “Higgs Boson,” a hypothetical particle that is supposed to help complete the Standard Model, researchers said, at least not in its traditional form. The Higgs would explain why other particles have mass or weight. The findings come from an international collaboration of scientists working at the particle collider in Batavia, Ill. Members of the Collider Detector at Fermilab, or CDF, collaboration project were smashing together protons, subatomic particles that sit at the cores of atoms, and antiprotons, exotic particles that are like protons but with opposite electrical charge. An unusually high number of collisions resulted in a specific set of byproducts, the investigators found. These byproducts consisted of a particle known as a W boson, along with two hadronic jets, beams of particles. These collision products are best explained by the fleeting existence of a new particle estimated to weigh about 140 GeV/c2, about halfway between the weight of an atom of silver and that of an atom of gold. The result has been submitted to the research journal Physical Review Letters. Researchers at the Large Hadron Collider, the world’s largest particle smasher, outside of Geneva, Switzerland, are expected to also check their data for signals of the particle.