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Wild Bunch: First five-quark particle turns up
Science News ^ | Week of July 5, 2003 | Peter Weiss

Posted on 07/06/2003 9:15:04 PM PDT by js1138

Physicists on three international teams have recently spotted what's most likely a long-sought subatomic particle known as a pentaquark. It contains five components—four quarks and one antiquark—which are among the most fundamental bits of matter yet known. No subatomic particle detected previously contains more than three of those building blocks.

"After 30 years of failing to find any convincing evidence for something that ought to be there, this recent news is certainly met with excitement," says nuclear physicist Andrew M. Sandorfi of Brookhaven National Laboratory in Upton, N.Y.

Although unusually complex, the newfound particle fits within the prevailing theoretical framework of particle physics, known as the standard model. The newly detected bit may be just the first member of a family of pentaquark particles. The find also underscores the possibility of discovering particles with four or six quarks.

To fathom how five quark components can coexist within one particle, theorists expect to reconsider their models of the interactions among quarks and gluons, the particles that bind quarks together. For instance, it's possible that the fivefold structure is not a spherical lump but rather a moleculelike arrangement in which a so-called kaon, which is made of a quark and an antiquark, orbits a neutron, which is made of three quarks.

"Exactly what form of the theory makes it work now becomes very interesting," says theorist Peter D. Barnes of Los Alamos (N.M.) National Laboratory.

If the pentaquark can exist in labs today, it probably also was present in the very first, fiery moments of the universe, says Takashi Nakano of Osaka University, leader of the team that found the pentaquark at Japan's SPring-8 synchrotron in Hyogo.

The experiments that appear to have bagged the elusive pentaquark weren't designed to look for it. "This is an example of serendipity," says Kenneth H. Hicks of Ohio University in Athens. He's a member of both the SPring-8 team and a group at the Thomas Jefferson National Accelerator Facility in Newport News, Va., that has confirmed the SPring-8 finding.

In 1997, Russian theorist Dmitri Diakonov and his colleagues predicted the existence of a pentaquark with a mass about 50 percent heavier than that of a hydrogen atom. The theorists then urged the SPring-8 team to reexamine data from an experiment in 2001 that might have inadvertently made the particle when it had gamma rays striking a piece of plastic.

When Nakano, Hicks, and their coworkers combed that data, they in fact found signs for about 20 pentaquarks. The team is slated to present its evidence in an upcoming Physical Review Letters.

Inspired by the SPring-8 findings, researchers at the Jefferson lab and the Institute of Theoretical and Experimental Physics in Moscow double-checked old data from different sorts of particle collisions and netted their own pentaquark candidates.

Besides its unprecedented quark count, a pentaquark is unusual in that it includes an exotic antiquark, the so-called strange antiquark. The composite particle also contains two up quarks and two down quarks—the same ones found in ordinary matter.

Nakano says the SPring-8 team is now analyzing data from new collisions that were generated explicitly to make pentaquarks. The aim is to nail down the identity and properties of this new entity. Meanwhile, the Jefferson lab has approved an experiment intended to boost its pentaquark production 20-fold, Hicks says.


TOPICS: Extended News; News/Current Events
KEYWORDS: pentaquark; pentaquarks; physics; quark; quarks
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1 posted on 07/06/2003 9:15:05 PM PDT by js1138
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To: Admin Moderator
Title should be:

Wild Bunch: First five-quark particle turns up
2 posted on 07/06/2003 9:17:20 PM PDT by js1138
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To: balrog666; RadioAstronomer; Right Wing Professor; js1138; Junior; Condorman; Doctor Stochastic; ...
ping
3 posted on 07/06/2003 9:31:12 PM PDT by js1138
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To: js1138
Way cool! Thanks for the ping. :-)
4 posted on 07/06/2003 9:34:36 PM PDT by RadioAstronomer
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To: js1138; ChemDoc
**FYI**
5 posted on 07/06/2003 9:44:30 PM PDT by TwoStep (Ignorance can be cured, stupid is forever!)
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To: js1138
BTTT
6 posted on 07/06/2003 9:49:12 PM PDT by Fiddlstix (~~~ http://www.ourgangnet.net ~~~~~)
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To: js1138
Doesn't four quarks and one antiquark = 3 quarks?
7 posted on 07/06/2003 9:50:29 PM PDT by Consort
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To: js1138
And, of course, this all happened by chance after the Big Bang! Yeah!
8 posted on 07/06/2003 9:51:51 PM PDT by LiteKeeper
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To: js1138
....this recent news is certainly met with excitement...



And I thought I needed a life.
9 posted on 07/06/2003 9:57:16 PM PDT by taxcontrol
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To: js1138
BTTT
10 posted on 07/06/2003 9:58:26 PM PDT by patricia
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To: LiteKeeper
And, of course, this all happened by chance after the Big Bang! Yeah!

Just what is chance? After all, even probability is governed by laws. Ever seen a fractal or a Mandelbrot set?

Seemingly impossible order out of sheer chaos. Funny how the Mandelbrot set appears EVERYWHERE in nature; in the shape of the mountains, or a tree, or a leaf . . .

11 posted on 07/06/2003 10:20:11 PM PDT by The Shootist
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To: js1138
Nice. Theory predicts something rather weird. Then experiment finds weird thing.
12 posted on 07/06/2003 10:26:30 PM PDT by Doctor Stochastic (Vegetabilisch = chaotisch is der Charakter der Modernen. - Friedrich Schlegel)
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To: Consort
Doesn't four quarks and one antiquark = 3 quarks?

No, a particle and an antiparticle annihilate each other only if they're of the same type -- for example, an electron and a positron (anti-electron), but not a proton and a positron.

There are six kinds of quarks, called up, down, top, bottom, strange, and charm. Each type has its own antiquark.

The five constituents of this newly discovered particle are said to be two up quarks, two down quarks, and a strange antiquark. There is no matching quark-antiquark pair here.

13 posted on 07/06/2003 10:29:51 PM PDT by Mitchell
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To: The Shootist
Ever see Fibonacci's Golden Number in creation?
14 posted on 07/06/2003 10:38:23 PM PDT by LiteKeeper
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To: js1138; Physicist
OK, physicist, would you mind putting this in english for me, or is this as far as the translator goes?

Good find js1138, thanks for the ping!
15 posted on 07/06/2003 11:20:46 PM PDT by Aric2000 (If the history of science shows us anything, it is that we get nowhere by labeling our ignorance god)
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To: js1138
"Buffalo quark go round the outside, round the outside, round the outside."
16 posted on 07/06/2003 11:21:16 PM PDT by TheErnFormerlyKnownAsBig (Soccer Mom's flee the Rats for Bush in his flight suit: I call this the Moisture Factor. MF high!)
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To: Consort
When can I get a antiquark drive for by vehicle?
17 posted on 07/06/2003 11:25:09 PM PDT by DannyTN (Note left on my door by a pack of neighborhood dogs.)
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To: js1138
You know I think the Supreme Court is made of of 6 quarks and 3 antiquarks.
18 posted on 07/06/2003 11:26:35 PM PDT by DannyTN (Note left on my door by a pack of neighborhood dogs.)
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To: js1138
the Jefferson lab has approved an experiment intended to boost its pentaquark production 20-fold

NO good can come from this, I'm telling you.

The ruination of mankind, famine, pestilence, degradation and death, all can be traced back to the Pentaquark.

Yada,yada,yada....
19 posted on 07/07/2003 3:29:06 AM PDT by tet68
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P L A C E M A R K E R
20 posted on 07/07/2003 3:54:54 AM PDT by PatrickHenry (Felix, qui potuit rerum cognoscere causas.)
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