Featured Research

from universities, journals, and other organizations

HAPPEx Results Hint At Strangely Magnetic Proton

Date:
May 14, 2005
Source:
Thomas Jefferson National Accelerator Facility
Summary:
New results from research performed at the Department of Energy's Jefferson Lab hint that strange quarks may contribute to the proton's magnetic moment.

New results from research performed at the Department of Energy's Jefferson Lab hint that strange quarks may contribute to the proton's magnetic moment. If confirmed by data to be taken later this year, these surprising results would indicate that strange quarks in the proton's quark-gluon sea contribute to at least one of the proton's intrinsic properties. The HAPPEx results strengthen the trend found by the SAMPLE experiment at MIT-Bates and the A4 experiment at the Mainz Laboratory in Germany. Results are being presented by University of Massachusetts at Amherst Physicist Krishna Kumar at the APS (American Physical Society) April Meeting Plenary Session Q0.00003.

Kumar is a Jefferson Lab user and a co-spokesperson on the Hall A Proton Parity Experiment (HAPPEx). The experiment measures the neutral weak force between a beam of electrons and target nuclei at a length scale of around one femtometer (roughly the size of a proton or neutron). These measurements will help physicists learn about the strong force that binds up and down quarks into protons and neutrons (nucleons) and the up, down and strange quark contributions to the nucleon's charge and current distributions.

In the experiment, HAPPEx researchers sent a polarized beam of electrons into hydrogen and Helium-4 nuclei. The researchers alternated the electron beam's polarization (spin) throughout the experiment. The electromagnetic force is mirror-symmetric (the electrons' spin will not affect the number of electrons scattered), while the weak force is not (electrons polarized one way will interact differently than electrons spinning oppositely). So measuring the fractional difference in the number of scattered electrons due to the beam's changing polarization allowed the researchers to calculate the neutral weak force.

According to Kumar, the results indicate that the strange quark contribution to the nucleon's charge and current distribution is zero within the sensitivity of each measurement. "However, there seems to be a trend towards a positive (non-zero) value for the average contribution of strange quarks to the proton's magnetic moment. If confirmed with more precise measurements, such a conclusion would be surprising and exciting," Kumar notes.

The HAPPEx experiments took data in June and July of 2004, and the final results are being prepared for submission to Physical Review Letters. Kumar says the next stage of HAPPEx may provide further insight. "The HAPPEx measurements will be repeated with higher precision later this year. A statistically significant measurement of a strange quark contribution to the charge and current distributions may be within reach," Kumar says.

Data from several recent experiments, including SLAC's (the Stanford Linear Accelerator Center) E158, the SAMPLE experiment at MIT-Bates, the A4 experiment at the Mainz Laboratory in Germany, and the G-Zero experiment at Jefferson Lab are beginning to shed further light on the weak interaction.

A white paper of this talk is available in the APS April Meeting 2005 Press Room.

###

Thomas Jefferson National Accelerator Facility's (Jefferson Lab's) basic mission is to provide forefront scientific facilities, opportunities and leadership essential for discovering the fundamental structure of nuclear matter; to partner in industry to apply its advanced technology; and to serve the nation and its communities through education and public outreach. Jefferson Lab is a Department of Energy Office of Science research facility managed by the Southeastern Universities Research Association.


Story Source:

The above story is based on materials provided by Thomas Jefferson National Accelerator Facility. Note: Materials may be edited for content and length.


Cite This Page:

Thomas Jefferson National Accelerator Facility. "HAPPEx Results Hint At Strangely Magnetic Proton." ScienceDaily. ScienceDaily, 14 May 2005. <www.sciencedaily.com/releases/2005/05/050513225657.htm>.
Thomas Jefferson National Accelerator Facility. (2005, May 14). HAPPEx Results Hint At Strangely Magnetic Proton. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2005/05/050513225657.htm
Thomas Jefferson National Accelerator Facility. "HAPPEx Results Hint At Strangely Magnetic Proton." ScienceDaily. www.sciencedaily.com/releases/2005/05/050513225657.htm (accessed October 21, 2014).

Share This



More Health & Medicine News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How Nigeria Beat Its Ebola Outbreak

How Nigeria Beat Its Ebola Outbreak

Newsy (Oct. 20, 2014) The World Health Organization has declared Nigeria free of Ebola. Health experts credit a bit of luck and the government's initial response. Video provided by Newsy
Powered by NewsLook.com
Another Study Suggests Viagra Is Good For The Heart

Another Study Suggests Viagra Is Good For The Heart

Newsy (Oct. 20, 2014) An ingredient in erectile-dysfunction medications such as Viagra could improve heart function. Perhaps not surprising, given Viagra's history. Video provided by Newsy
Powered by NewsLook.com
Ebola Worries End for Dozens on U.S. Watch Lists

Ebola Worries End for Dozens on U.S. Watch Lists

Reuters - US Online Video (Oct. 20, 2014) Forty-three people who had contact with Thomas Eric Duncan, the first person diagnosed with Ebola in the U.S., were cleared overnight of twice-daily monitoring after 21 days of showing no symptoms. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
CDC Calls for New Ebola Safety Guidelines

CDC Calls for New Ebola Safety Guidelines

AP (Oct. 20, 2014) Centers for Disease Control and Prevention Director Dr. Tom Frieden laid out new guidelines for health care workers when dealing with the deadly Ebola virus including new precautions when taking off personal protective equipment. (Oct. 20) Video provided by AP
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


Health & Medicine

Mind & Brain

Living & Well

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