New particle turns up in Japan

Physicsweb ^ | Nov 14, 2003 | Belle Dumé

[Diddley]

The Belle collaboration at the KEK laboratory in Japan has discovered a new sub-atomic particle which it is calling the "X(3872)". The particle does not fit into any known particle scheme and theorists are speculating that it might be a hitherto unseen type of meson that contains four quarks (arxiv.org/abs/hep-ex/0309032; Phys. Rev. Lett. to be published).

The discovery has been confirmed by the CDF collaboration at Fermilab in the US, where the new particle is being called the "mystery meson". Mesons are particles that contain a quark and an antiquark that are held together by the strong nuclear force.

Since there are six different "flavours" of quark - up, down, strange, charm, bottom and top - it is possible to form a large number of different mesons.

The Belle team measured the decay of B-mesons - mesons that contain a bottom quark - produced in electron-positron collisions at the KEK B-factory in Japan. The team plotted the number of candidate events for B mesons against mass and observed a significant spike in the distribution at 0.775 GeV. This corresponds to a mass of nearly 3872 MeV. The particle decayed almost immediately into other, longer lived particles.

The KEK team says that the mass of this new meson is higher than theoretical predictions. Moreover, the way in which it decays also differs from theory. One possibility is that current models of the strong force need to be modified. Alternatively it could be that X(3872) is the first example of a "molecular state" meson that contains two quarks and two antiquarks.

Until recently particle physicists had only ever detected particles that contain two or three quarks. However, in the past year evidence has emerged for another four-quark particle known as the Ds(2317) and a five-quark particle known as the pentaquark.

Author Belle Dumé is Science Writer at PhysicsWeb

[general_re]

New particle turns up in Japan

Ah, well - that's my fault. I must have left it in my hotel room the last time I went to Japan on business. Sorry about that.

[BostonianRightist]

I think I understood 4 of those sentences!

[Virginia-American]

Diddley: Thanks.

PH: Ping the science crew.

[Diddley]

[2]
I'd put in for a claim if I were you. :-)

[demkicker]

Bump to the Mensa crowd....

[Paul Atreides]

It's 'cause you don't eat right.

[jwalburg]

Eating subatomic particles in sushi may be harmful to your health says CDC.

[William Tell]

general_re said: "I must have left it in my hotel room the last time I went to Japan on business."

You must be running about a quark low, then.

[Paul Atreides]

Who stranded me in Japan?

[WackyKat]

They should name it the "Fugu"

[P.O.E.]

Yatta?

[Diddley]

I find the wit of FReepers to be hilarious. :-)

[BMC1]

HUH??????? What did she say and what thehell is it?

[general_re]

I think the cleaning lady must have swiped it. I tried calling about it, but the manager said that nobody had returned it to the desk. Now somebody's found my particle, and claimed it for themselves - I'm calling my lawyer first thing on Monday, that's for sure...

[general_re]

It's 'cause you don't eat right.

I think it was the wasabi. Or maybe the sake. I always misplace stuff after having one too many of those...

[William Tell]

general_re said: "I think the cleaning lady must have swiped it."

If you're feeling energetic, you might check to see if there were any anti-quarks in the area at the time it disappeared.

[AmericanVictory]

In the hunting of this quark, did they hunt it with railway shares and hot buttered toast?

[Diddley]

They looked up, they looked down. They looked at the bottom and the top, but strangely, they were charmed (and they created a mess on it).

[GeronL]

LOST: Particle from Ennis Texas. May wander long distances. Has protons and neutrons. Reward if found and returned safely