Featured Research

from universities, journals, and other organizations

Is It Or Isn't It? Pentaquark Debate Heats Up

Date:
May 3, 2005
Source:
Thomas Jefferson National Accelerator Facility
Summary:
New data from the Department of Energy's Jefferson Lab shows the pentaquark doesn't appear in one place it was expected. The result contradicts earlier findings in this same region and adds to the controversy over whether research groups from around the world have caught a glimpse of the so-called pentaquark, a particle built of five quarks.

New data from Jefferson Lab shows the θ+ pentaquark doesn't appear in one place it was expected. The result contradicts earlier findings in this same region and adds to the controversy over whether research groups from around the world have caught a glimpse of a pentaquark, a particle built of five quarks.
Credit: Image : JLab

New data from the Department of Energy's Jefferson Lab shows the pentaquark doesn't appear in one place it was expected. The result contradicts earlier findings in this same region and adds to the controversy over whether research groups from around the world have caught a glimpse of the so-called pentaquark, a particle built of five quarks.

Researchers in Jefferson Lab's CEBAF Large Acceptance Spectrometer (CLAS) collaboration took data with a high energy photon beam on a liquid hydrogen target. In a similar experiment conducted by the SAPHIR collaboration at the ELectron Stretcher Accelerator (ELSA) in Bonn, Germany, a signal revealing a pentaquark was observed. However, the Jefferson Lab team, whose data contained two orders of magnitude better statistics, found no evidence of the pentaquark. Raffaella De Vita, a staff scientist at Italy's Istituto Nazionale di Fisica Nucleare in Genova and a Jefferson Lab CLAS collaboration member, presented the preliminary results in a post-deadline talk at the American Physical Society's (APS) April Meeting, Session B4 on April 16.

What the Jefferson Lab CLAS collaboration data shows is that in this particular channel there is no pentaquark at a level of precision at least 50 times higher than the published SAPHIR result. The CLAS researchers in this analysis will take another round of data in 2006 to look for the pentaquark in a different channel and at higher energies.

Jefferson Lab researchers are currently in the midst of several dedicated hunts for the pentaquark, including an experiment repeating Jefferson Lab's original pentaquark search with much higher statistics. That data is still being analyzed, and researchers expect to present the results later this year.

The first pentaquark sighting was announced by SPring-8 researchers in the spring of 2003, and the same year, Jefferson Lab, ITEP and ELSA researchers announced that they, too, may have spotted tantalizing hints of the particle in data previously taken in other experiments. For instance, the SAPHIR collaboration's evidence of the Theta-plus pentaquark came from data they took in 1997/98 and indicated a pentaquark mass of 1540 MeV (million electron volts). Several experiments since then have backed up these early sightings, while others have failed to confirm the sightings.

Most ordinary matter is built of quarks. They're usually found in twos (as particles called mesons) and threes (as particles called baryons, such as protons and neutrons). While the pentaquark's five-quark configuration is not forbidden by the theory of the strong interaction, finding one would be the first sighting of an exotic baryon.



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. "Is It Or Isn't It? Pentaquark Debate Heats Up." ScienceDaily. ScienceDaily, 3 May 2005. <www.sciencedaily.com/releases/2005/05/050502203532.htm>.
Thomas Jefferson National Accelerator Facility. (2005, May 3). Is It Or Isn't It? Pentaquark Debate Heats Up. ScienceDaily. Retrieved August 22, 2014 from www.sciencedaily.com/releases/2005/05/050502203532.htm
Thomas Jefferson National Accelerator Facility. "Is It Or Isn't It? Pentaquark Debate Heats Up." ScienceDaily. www.sciencedaily.com/releases/2005/05/050502203532.htm (accessed August 22, 2014).

Share This




More Matter & Energy News

Friday, August 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. Video provided by Reuters
Powered by NewsLook.com
Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. Video provided by Newsy
Powered by NewsLook.com
Researcher Testing on-Field Concussion Scanners

Researcher Testing on-Field Concussion Scanners

AP (Aug. 19, 2014) Four Texas high school football programs are trying out an experimental system designed to diagnose concussions on the field. The technology is in response to growing concern over head trauma in America's most watched sport. (Aug. 19) Video provided by AP
Powered by NewsLook.com
Green Power Blooms as Japan Unveils 'hydrangea Solar Cell'

Green Power Blooms as Japan Unveils 'hydrangea Solar Cell'

AFP (Aug. 19, 2014) A solar cell that resembles a flower is offering a new take on green energy in Japan, where one scientist is searching for renewables that look good. Duration: 01:29 Video provided by AFP
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