Why is there matter in the universe and not antimatter, its opposite?
Physicists at Fermi National Accelerator Laboratory, including John Ellison, a professor of physics at UC Riverside, have announced that they have found evidence for a significant violation of matter-antimatter symmetry in decays of B-mesons, which are exotic particles produced in high energy particle collisions.
To arrive at their result, the research team, known as the DZero collaboration, analyzed billions of proton-antiproton collisions at Fermilab's Tevatron particle collider, and found a 1 percent excess of pairs of muons over pairs of antimuons produced in the decays of B-mesons. Muons, which occur naturally in cosmic rays, are fundamental particles similar to electrons but 200 times heavier.
Ellison said this result is exciting and surprising since it is not predicted in the Standard Model, the comprehensive theory that explains the interactions between all fundamental elementary particles.
He explained that the dominance of matter we observe in the universe is possible only if there are differences, called "CP violation," in the behavior of particles and antiparticles.
"The reason this is important is that CP violation – the fact that physics does not look the same when particles and antiparticles are interchanged and all processes are mirror-reflected – is one of the three ingredients identified by Andrei Sakharov, the famous Soviet physicist and dissident, needed to explain the matter-antimatter asymmetry observed in our universe," Ellison said. "That the universe is completely dominated by matter is a mystery because the Big Bang theory predicts that there should have been equal amounts of matter and antimatter."
According to Ellison and his DZero peers, the explanation for the dominance of matter in the present day universe is that the CP violation treated matter and antimatter differently and allowed the early universe to evolve into a situation with matter dominating completely over antimatter.
"CP violation as predicted in the Standard Model has been observed before but at a level many orders of magnitude too small to explain the asymmetry," Ellison said. "This is the first evidence for anomalous CP violation. If confirmed by further measurements, this points to new physics phenomena in particle interactions that give rise to the matter-antimatter asymmetry, and may be another step forward in our understanding of why matter dominates over antimatter in the universe."
The DZero result is based on data collected over the last eight years by the DZero experiment at Fermilab. Besides Ellison, the UC Riverside co-authors of the paper, submitted for publication in Physical Review D, are Ann Heinson, Liang Li, Mark Padilla, and Stephen Wimpenny.
DZero is an international experiment of about 500 physicists from 86 institutions in 19 countries. It is supported by the U.S. Department of Energy, the National Science Foundation and a number of international funding agencies.
Fermilab is a national laboratory funded by the Office of Science of the U.S. Department of Energy.
The University of California, Riverside (www.ucr.edu) is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of about 18,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion.
A broadcast studio with fiber cable to the AT&T Hollywood hub is available for live or taped interviews. To learn more, call (951) UCR-NEWS.
Iqbal Pittalwala | EurekAlert!
A better way to weigh millions of solitary stars
15.12.2017 | Vanderbilt University
A chip for environmental and health monitoring
15.12.2017 | Friedrich-Alexander-Universität Erlangen-Nürnberg
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
15.12.2017 | Power and Electrical Engineering
15.12.2017 | Materials Sciences
15.12.2017 | Life Sciences