The discovery of the single top confirms important parameters of particle physics, including the total number of quarks, and has significance for the ongoing search for the Higgs particle at Fermilab’s Tevatron, currently the world’s most powerful operating particle accelerator.
Previously, top quarks had only been observed when produced by the strong nuclear force. That interaction leads to the production of pairs of top quarks. The production of single top quarks, which involves the weak nuclear force and is harder to identify experimentally, has now been observed, almost 14 years to the day of the top quark discovery in 1995.
Searching for single-top production makes finding a needle in a haystack look easy. Only one in every 20 billion proton-antiproton collisions produces a single top quark. Even worse, the signal of these rare occurrences is easily mimicked by other “background” processes that occur at much higher rates.
"Observation of the single top quark production is an important milestone for the Tevatron program," said Dr. Dennis Kovar, Associate Director of the Office of Science for High Energy Physics at the U.S. Department of Energy. "Furthermore, the highly sensitive and successful analysis is an important step in the search for the Higgs."
Discovering the single top quark production presents challenges similar to the Higgs boson search in the need to extract an extremely small signal from a very large background. Advanced analysis techniques pioneered for the single top discovery are now in use for the Higgs boson search. In addition, the single top and the Higgs signals have backgrounds in common, and the single top is itself a background for the Higgs particle.
To make the single-top discovery, physicists of the CDF and DZero collaborations spent years combing independently through the results of proton-antiproton collisions recorded by their experiments, respectively. Each team identified several thousand collision events that looked the way experimenters expect single top events to appear. Sophisticated statistical analysis and detailed background modeling showed that a few hundred collision events produced the real thing. On March 4, the two teams submitted their independent results to Physical Review Letters.
The two collaborations earlier had reported preliminary results on the search for the single top. Since then, experimenters have more than doubled the amount of data analyzed and sharpened selection and analysis techniques, making the discovery possible. For each experiment, the probability that background events have faked the signal is now only one in nearly four million, allowing both collaborations to claim a bona fide discovery that paves the way to more discoveries.
“I am thrilled that CDF and DZero achieved this goal,” said Fermilab Director Pier Oddone. “The two collaborations have been searching for this rare process for the last fifteen years, starting before the discovery of the top quark in 1995. Investigating these subatomic processes in more detail may open a window onto physics phenomena beyond the Standard Model.”
Kurt Riesselmann | EurekAlert!
Electronic evidence of non-Fermi liquid behaviors in an iron-based superconductor
11.12.2018 | Science China Press
Physicists edge closer to controlling chemical reactions
11.12.2018 | Moscow Institute of Physics and Technology
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.
Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...
New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals
Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.
Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.
Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...
10.12.2018 | Event News
06.12.2018 | Event News
03.12.2018 | Event News
11.12.2018 | Physics and Astronomy
11.12.2018 | Materials Sciences
11.12.2018 | Information Technology