Observation of pentaquarks

[lajoswinkler]

http://arxiv.org/abs/1507.03414

Observations of exotic structures in the J/Èp channel, that we refer to as pentaquark-charmonium states, in Λ0b→J/ÈK−p decays are presented. The data sample corresponds to an integrated luminosity of 3/fb acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis is performed on the three-body final-state that reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J/Èp mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380±8±29 MeV and a width of 205±18±86 MeV, while the second is narrower, with a mass of 4449.8±1.7±2.5 MeV and a width of 39±5±19 MeV. The preferred JP assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.

This has been a fruitful day for natural sciences.

[LittleBlueGaming]

http://press.web.cern.ch/press-releases/2015/07/cerns-lhcb-experiment-reports-observation-exotic-pentaquark-particles

Just saw this, sounds exciting but I really have no idea what it implies.

[Specialist290]

Looks like we have two new threads on the same bit of news. Merging

[magnemoe]

http://press.web.cern.ch/press-releases/2015/07/cerns-lhcb-experiment-reports-observation-exotic-pentaquark-particles

Just saw this, sounds exciting but I really have no idea what it implies.

That is the problem, few know.

How stable are they for one, my guess is that they don't last very long.

[K^2]

How stable are they for one, my guess is that they don't last very long.

They are all excited states which decay via strong interaction, so yeah, extremely unstable.

[PB666]

They are all excited states which decay via strong interaction, so yeah, extremely unstable.

That particular pentaquark type also has an anti-quark (as part of a pair) so . . . . . . .

[K^2]

That particular pentaquark type also has an anti-quark

Any pentaquark will have an anti-quark. That's required by color-neutrality rule. The fact that it's a cc-bar makes it a little less stable than one expects with a mismatched anti-quark, that's true. But even the best case, which is probably a p + K (uddds-bar) pentaquark (totally guessing here), the life time will be extremely short. Even À+, which is ud-bar, which is as good as it gets for a meson, has a half-life of only 29ns. And that thing is almost 10 times lighter than a proton. The resonances that have been detected are more than 4 times heavier.

[WinkAllKerb'']

(plox don't poo that's fast and that's small can't see it so much it's small and decay even faster ... agree ... so boring @k^2 ... universe related reverse the time scale ...)

Edited July 18, 2015 by WinkAllKerb''
that's multithread ... bah nevermind ... the matricial matrix don't care ...

[PakledHostage]

I stumbled on this video a moment ago and thought I'd share it: