Featured Research

from universities, journals, and other organizations

Clue to antimatter conundrum: Physicists find evidence for significant matter-antimatter asymmetry

Date:
May 21, 2010
Source:
DOE/Fermi National Accelerator Laboratory
Summary:
Scientists at Fermi National Accelerator Laboratory have announced that they have found evidence for significant violation of matter-antimatter symmetry in the behavior of particles containing bottom quarks beyond what is expected in the current theory, the Standard Model of particle physics. The new result indicates a one percent difference between the production of pairs of muons and pairs of antimuons in the decay of B mesons produced in high-energy collisions at Fermilab's Tevatron particle collider.

The DZero collaboration has found evidence for a new way in which elementary particles break the matter-antimatter symmetry of nature. This new type of CP violation is in disagreement with the predictions of the theoretical framework known as the Standard Model of particles and their interactions. The effect ultimately may help to explain why the universe is filled with matter while antimatter disappeared shortly after the big bang.
Credit: DZero collaboration

Scientists of the DZero collaboration at the Department of Energy's Fermi National Accelerator Laboratory have announced that they have found evidence for significant violation of matter-antimatter symmetry in the behavior of particles containing bottom quarks beyond what is expected in the current theory, the Standard Model of particle physics.

The new result, submitted for publication in Physical Review D by the DZero collaboration, an international team of 500 physicists, indicates a one percent difference between the production of pairs of muons and pairs of antimuons in the decay of B mesons produced in high-energy collisions at Fermilab's Tevatron particle collider.

The dominance of matter that we observe in the universe is possible only if there are differences in the behavior of particles and antiparticles. Although physicists have observed such differences (called "CP violation") in particle behavior for decades, these known differences are much too small to explain the observed dominance of matter over antimatter in the universe and are fully consistent with the Standard Model. If confirmed by further observations and analysis, the effect seen by DZero physicists could represent another step towards understanding the observed matter dominance by pointing to new physics phenomena beyond what we know today.

Using unique features of their precision detector and newly developed analysis methods, the DZero scientists have shown that the probability that this measurement is consistent with any known effect is below 0.1 percent (3.2 standard deviations).

"This exciting new result provides evidence of deviations from the present theory in the decays of B mesons, in agreement with earlier hints," said Dmitri Denisov, co-spokesperson of the DZero experiment, one of two collider experiments at the Tevatron collider. Last year, physicists at both Tevatron experiments, DZero and CDF, observed such hints in studying particles made of a bottom quark and a strange quark.

When matter and anti-matter particles collide in high-energy collisions, they turn into energy and produce new particles and antiparticles. At the Fermilab proton-antiproton collider, scientists observe hundreds of millions every day. Similar processes occurring at the beginning of the universe should have left us with a universe with equal amounts of matter and anti-matter. But the world around is made of matter only and antiparticles can only be produced at colliders, in nuclear reactions or cosmic rays. "What happened to the antimatter?" is one of the central questions of 21st-century particle physics.

To obtain the new result, the DZero physicists performed the data analysis "blind," to avoid any bias based on what they observe. Only after a long period of verification of the analysis tools, did the DZero physicists look at the full data set. Experimenters reversed the polarity of their detector's magnetic field during data collection to cancel instrumental effects.

"Many of us felt goose bumps when we saw the result," said Stefan Soldner-Rembold, co-spokesperson of DZero. "We knew we were seeing something beyond what we have seen before and beyond what current theories can explain."

The precision of the DZero measurements is still limited by the number of collisions recorded so far by the experiment. Both CDF and DZero therefore continue to collect data and refine analyses to address this and many other fundamental questions.

"The Tevatron collider is operating extremely well, providing Fermilab scientists with unprecedented levels of data from high energy collisions to probe nature's deepest secrets. This interesting result underlines the importance and scientific potential of the Tevatron program," said Dennis Kovar, Associate Director for High Energy Physics in DOE's Office of Science.

The DZero result is based on data collected over the last eight years by the DZero experiment: over 6 inverse femtobarns in total integrated luminosity, corresponding to hundreds of trillions of collisions between protons and antiprotons in the Tevatron collider.

"Tevatron collider experiments study high energy collisions in every detail, from searches for the Higgs boson, to precision measurement of particle properties, to searches for new and yet unknown laws of nature. I am delighted to see yet another exciting result from the Tevatron," said Fermilab Director Pier Oddone.

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, operated under contract by Fermi Research Alliance, LLC.


Story Source:

The above story is based on materials provided by DOE/Fermi National Accelerator Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. The D0 Collaboration: V.M. Abazov, et al. Evidence for an anomalous like-sign dimuon charge asymmetry. Physical Review D, 2010; (submitted) [link]

Cite This Page:

DOE/Fermi National Accelerator Laboratory. "Clue to antimatter conundrum: Physicists find evidence for significant matter-antimatter asymmetry." ScienceDaily. ScienceDaily, 21 May 2010. <www.sciencedaily.com/releases/2010/05/100520212139.htm>.
DOE/Fermi National Accelerator Laboratory. (2010, May 21). Clue to antimatter conundrum: Physicists find evidence for significant matter-antimatter asymmetry. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2010/05/100520212139.htm
DOE/Fermi National Accelerator Laboratory. "Clue to antimatter conundrum: Physicists find evidence for significant matter-antimatter asymmetry." ScienceDaily. www.sciencedaily.com/releases/2010/05/100520212139.htm (accessed October 2, 2014).

Share This



More Matter & Energy News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Japan Looks To Faster Future As Bullet Train Turns 50

Japan Looks To Faster Future As Bullet Train Turns 50

Newsy (Oct. 1, 2014) Japan's bullet train turns 50 Wednesday. Here's a look at how it's changed over half a century — and the changes it's inspired globally. Video provided by Newsy
Powered by NewsLook.com
US Police Put Body Cameras to the Test

US Police Put Body Cameras to the Test

AFP (Oct. 1, 2014) Police body cameras are gradually being rolled out across the US, with interest surging after the fatal police shooting in August of an unarmed black teenager. Duration: 02:18 Video provided by AFP
Powered by NewsLook.com
Raw: Japan Celebrates 'bullet Train' Anniversary

Raw: Japan Celebrates 'bullet Train' Anniversary

AP (Oct. 1, 2014) A ceremony marking 50 years since Japan launched its Shinkansen bullet train was held on Wednesday in Tokyo. The latest model can travel from Tokyo to Osaka, a distance of 319 miles, in two hours and 25 minutes. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Robotic Hair Restoration

Robotic Hair Restoration

Ivanhoe (Oct. 1, 2014) A new robotic procedure is changing the way we transplant hair. The ARTAS robot leaves no linear scarring and provides more natural results. Video provided by Ivanhoe
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins