Featured Research

from universities, journals, and other organizations

NuTeV Anomaly Helps Shed Light On Physics Of The Nucleus

Date:
July 9, 2009
Source:
DOE/Thomas Jefferson National Accelerator Facility
Summary:
A new calculation clarifies the complicated relationship between protons and neutrons in the atomic nucleus and offers a fascinating resolution of the famous NuTeV Anomaly.

A new calculation clarifies the complicated relationship between protons and neutrons in the atomic nucleus and offers a fascinating resolution of the famous NuTeV Anomaly.

The calculation, published in the journal Physical Review Letters on June 26, was carried out by a collaboration of researchers from the Department of Energy's Thomas Jefferson National Accelerator Facility, Tokai University and the University of Washington. It grew out of attempts to make sense of the complex environment found in the nucleus of the atom.

The calculation began with the EMC Effect, a famous result in the world of nuclear physics that showed that the structures of protons and neutrons in a nucleus are different from protons and neutrons found outside a nucleus.

"I was at CERN when the EMC Effect was discovered more than 20 years ago," said Anthony Thomas, Jefferson Lab Chief Scientist and an author on the paper. "It's such a fundamental piece of information about the structure of nuclei that I wanted to understand it."

Thomas and his colleagues, Ian Cloët, a JSA Thesis prize winner in 2008, and Wolfgang Bentz, a long term visitor at Jefferson Lab in 2008, had theorized that the internal structures of protons and neutrons are modified by the presence of other protons and neutrons inside the nucleus.

Meanwhile, another landmark result, the NuTeV Anamoly, provided Thomas and his colleagues with another puzzle regarding the nucleus. Experimenters at Fermilab's NuTeV (Neutrinos at the Tevatron) experiment sent a beam of neutrinos into a steel target and measured the ratio of two types of subatomic particles - neutrinos and muons - that emerged. They found that about one percent fewer neutrino-target collisions produced neutrinos than predicted by the Standard Model.

"Many people were convinced that they had discovered evidence for physics beyond the Standard Model," said Thomas.

He and his colleagues pored over the experimental information and began applying their theories for the EMC Effect to it. They found that one common assumption that was used in the analysis of the NuTeV data involved a correction for a natural imbalance in the number of protons and neutrons in the nucleus of iron, the most common element in NuTeV's steel target.

"The correction made for the extra neutrons involved a subtraction of the structure function of the extra neutrons," Cloët explained. "But according to our theoretical model of the EMC Effect, those extra neutrons generate a force that subtly changes the structure of every proton and neutron in the nucleus."

The theorists went further, combining this newly discovered effect with another correction for the difference in masses of different quarks in the protons and neutrons (charge symmetry violation). When they applied the two corrections to the NuTeV analysis, they found that the experiment showed excellent agreement with the Standard Model.

As a consequence, the NuTeV result may now be interpreted as providing crucial evidence for the idea that the structure of a proton or neutron is fundamentally modified when it is bound in a nucleus.

"Now, the next thing is to carry out an experiment to test this explanation directly," Thomas said. "You can make measurements that directly test whether it's right or wrong."

This research was funded by the Office of Nuclear Physics within the Department of Energy's Office of Science. Jefferson Lab is managed and operated by Jefferson Science Associates, LLC, for the Department of Energy.


Story Source:

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


Journal Reference:

  1. I. C. Cloët, W. Bentz, and A. W. Thomas. Isovector EMC Effect and the NuTeV Anomaly. Phys. Rev. Lett., 102, 252301 (2009) [4 pages] DOI: 10.1103/PhysRevLett.102.252301

Cite This Page:

DOE/Thomas Jefferson National Accelerator Facility. "NuTeV Anomaly Helps Shed Light On Physics Of The Nucleus." ScienceDaily. ScienceDaily, 9 July 2009. <www.sciencedaily.com/releases/2009/06/090629132252.htm>.
DOE/Thomas Jefferson National Accelerator Facility. (2009, July 9). NuTeV Anomaly Helps Shed Light On Physics Of The Nucleus. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2009/06/090629132252.htm
DOE/Thomas Jefferson National Accelerator Facility. "NuTeV Anomaly Helps Shed Light On Physics Of The Nucleus." ScienceDaily. www.sciencedaily.com/releases/2009/06/090629132252.htm (accessed April 17, 2014).

Share This



More Matter & Energy News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) — After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) — German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. Video provided by Newsy
Powered by NewsLook.com
Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

TheStreet (Apr. 16, 2014) — The Porsche Spyder 918 proves that, in an automotive world obsessed with fuel efficiency, the supercar is not dead. Porsche North America CEO Detlev von Platen attributes the brand's consistent sales growth -- 21% in 2013 -- with an investment in new technology and expanded performance dynamics. The hybrid Spyder 918 has 887 horsepower and 944 lb-ft of torque, but it can run 18 miles on just an electric charge. The $845,000 vehicle is not a consumer-targeted vehicle but a brand statement. Video provided by TheStreet
Powered by NewsLook.com
Industry's Optimism Shines At New York Auto Show

Industry's Optimism Shines At New York Auto Show

Newsy (Apr. 16, 2014) — After seeing auto sales grow last month, there's plenty for the industry to celebrate as it rolls out its newest designs. Video provided by Newsy
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:
from the past week

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