Crashing debut of an exotic heavy particle?A high-speed positron positron: see antiparticle.
Subatomic particle having the same mass as an electron but with an electric charge of +1 (an electron has a charge of −1). It constitutes the antiparticle (see antimatter) of an electron. , the antimatter antimatter: see antiparticle.
Substance composed of elementary particles having the mass and electric charge of ordinary matter (such as electrons and protons) but for which the charge and related magnetic properties are opposite in sign. counterpart of an electron, smashes head-on into an onrushing proton. It penetrates the particle, striking one of the proton's constituent quarks; then, picking up an enormous amount of momentum from the struck quark, it rebounds nearly straight back.
Such spectacular events are rare among the thousands of positron-proton collisions monitored at the HERA particle accelerator particle accelerator, apparatus used in nuclear physics to produce beams of energetic charged particles and to direct them against various targets. Such machines, popularly called atom smashers, are needed to observe objects as small as the atomic nucleus in studies in Hamburg, Germany. Most of the time, the particles either miss or merely glance off each other.
Nonetheless, collisions in which positrons are sharply deflected seem to occur more frequently than expected, based on the standard model of particle physics particle physics
or high-energy physics
Study of the fundamental subatomic particles, including both matter (and antimatter) and the carrier particles of the fundamental interactions as described by quantum field theory. . The standard model represents the current theoretical understanding of the fundamental particles and the forces of nature (SN: 7/1/95, p. 10).
Members of the large international team operating the H1 detector at HERA observed 12 high-momentum events in 3 years' worth of data, whereas theory would predict only 4.7 such events. Independently, the physicists operating the ZEUS detector at HERA obtained comparable results. Each group describes its findings in separate papers submitted for publication to Zeitschrift fur Physik.
"It might be that what we are seeing is some statistical fluctuation," says ZEUS team member Malcolm Derrick of Argonne (Ill.) National Laboratory. "On the other hand, both experiments independently see an excess, so we have some confidence that maybe it's a real effect."
The findings, if confirmed, suggest the existence of new particles or forces that are not part of the standard model. One possibility is that a positron may merge briefly with a quark, creating a particle that theorists call a leptoquark. This particle would then decay and spit out Verb 1. spit out - spit up in an explosive manner
cough out, cough up, expectorate, spit up, spit out - discharge (phlegm or sputum) from the lungs and out of the mouth
2. a positron.
Alternatively, "the underlying effect might not be the formation of a new particle but the action of a new force that causes a stronger interaction between the positron and the quark than anything in the standard model," says physicist David J David J. Haskins (b. April 24, 1957, in Northampton, England) is a British alternative rock musician. He was the bassist for the seminal gothic rock band Bauhaus. Life and work . Miller of University College London “UCL” redirects here. For other uses, see UCL (disambiguation).
University College London, commonly known as UCL, is the oldest multi-faculty constituent college of the University of London, one of the two original founding colleges, and the first British .
A third possibility is that quarks are themselves made up of still smaller building blocks. Last year, physicists at the Fermi National Accelerator Laboratory Fermi National Accelerator Laboratory (Fermilab), physical science research center located near Batavia, Ill., est. 1968 as the National Accelerator Laboratory, renamed 1974 in honor of Enrico Fermi. It was built on the site of the former village of Weston. in Batavia, Ill., detected a subtle effect hinting at such a quark substructure substructure /sub·struc·ture/ (-struk-chur) the underlying or supporting portion of an organ or appliance; that portion of an implant denture embedded in the tissues of the jaw.
n. in debris scattered from high-energy collisions between protons and antiprotons (SN: 2/17/96, p. 102). However, subsequent analysis showed it was possible to explain the results in terms of conventional theory.
Which interpretation, if any, proves correct depends on future research. "As we collect more data, we'll find out whether our initial results hold up," Derrick says. The researchers expect to double the number of observations during 1997.
"The [high-momentum] events are so spectacular that we can see them immediately when they occur," Derrick adds. "We don't have to collect all the data before analyzing them." Stay tuned!