Exotic Pentaquark Particle


Does the Particle known as the Pentaquark Exist?


The OLD version of this page is linked here.


At the American Physical Society meeting held during April 16-19, 2005, the CLAS collaboration presented results for one out of a series of high-statistics experiments. This one was expected to show evidence for the pentaquark, but surprisingly, no evidence was found. This contradicts an earlier low-statistics measurement, and shows the importance of getting high statistics. The CLAS detector at Thomas Jefferson National Accelerator Laboratory is perhaps the only place in the world that can acquire this quantity of data for this photoproduction reaction. This is a prime example of the scientific method at work (results must be reproducible at high statistics before they are accepted).

However, the existence of the pentaquark is still an open question. There are many other experiments with positive evidence for the "Theta" pentaquark. Now the task of proving the existence of the "Theta" will be more difficult. Stay tuned as progress continues.

The following links may be useful for more information:

News Release from Jefferson Lab (Word document) .

Explanation for the general public.

Explanation for the general scientist.

Explanation for physicists .

Article from Science Magazine, Nov. 2004 (pdf file) .

Article from Physics World Magazine, 2005 (pdf file) .



Other useful links:

R. DeVita's presentation at the American Physical Society meeting (Tampa, FL, 2005): PDF

Earlier analysis presented at the International Conference on Hadron Spectroscopy (2003): PDF




Last modified: April 15, 2005
Kenneth Hicks