Large Hadron Collider discovers new pentaquark particle

I think it's really something when new particles or their signatures pop-up for real after being predicted by models.
http://www.bbc.com/news/science-environment-33517492

 

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Me two.

 

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Except it wasn't expected: “I was not expecting this. It’s of kind of amazing—not many physicists can say they helped discover a new state of matter at my age.”
http://www.symmetrymagazine.org/article/july-2015/lhc-physicists-discover-five-quark-particle

One has to wonder what other unexpected quark states might arise when pb-pb collisions start in the fall. stable strange quark matter (sqm)? some models predict these to be sufficiently stable to engage in continuous fusion, growing larger.

 

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Agreed. and still much more to be discovered I would suggest.

 

Except it wasn't expected, nor was it predicted.

“We didn’t go out looking for a pentaquark,” Stone says, “It’s a particle that found us.” http://www.symmetrymagazine.org/article/july-2015/lhc-physicists-discover-five-quark-particle

 

Which part of "it was first predicted to exist in the 1960s" are you having trouble with?

 

http://arxiv.org/abs/1507.03414

The more stable of the two pentaquarks hangs around only about 1/400th time of the J/Ψ meson (light-quark analogue: \(\rho^0\)). Or roughly as long as the \(\eta_c\) meson (light-quark analog: \(\pi^0\)).

 

The part where the quarks were first predicted to exist in the 1960s, which is the part you are having difficulty with. Gellman was not predicting pentaquark combinations.

 

very unstable. needs a strange quark to stabilize it for longer half-life.

 

"In 1964, two physicists - Murray Gell Mann and George Zweig - independently proposed the existence of the subatomic particles known as quarks."
"This model also allowed for other quark states, such as the pentaquark. This purely theoretical particle was composed of four quarks and an antiquark (the anti-matter equivalent of an ordinary quark)."
(From the link in the OP.)

"Gell-Mann predicted that some known particles, such as the pion, were made up of two quarks, and others, such as the proton and neutron, were made up of three quarks. But he also postulated that particles made up of four or five quarks could exist."

 

"postulated" but not predicted. These have more robust theory for their predictions since. To quote again from the researcher: "I was not expecting this." What part of "not expecting this" do you not understand?

 

They didn't do the experiment to specifically look for a pentaquark, they just happened to find one co-incidentally.

That doesn't mean that they didn't expect it to exist.

 

There must be something to this stuff.

 

For a theoretical model postulated and predicted is the same thing. The prediction is derived from the model. The standard model has great predictive power. That's what sweetpea is commenting about.

 

Yes, I did mean it in that sense.

From rpenner's link...

My bold
So I'm understanding that to mean pentaquarks were proposed, postulated or predicted in 1979 for some models.
Now a pair have been found in an experiment not actually conducted to look for pentaquarks.

 

Question. Not to fear monger, but sites have been going on and on that this is very similar to the theoretical and theoretically dangerous strangelet. Do they have any relation? Would Pb - Pb collisions be unpredictable as well creating a bit of chaos?

 

Would the discovery of the pentaquark give credence to theories such as these?


New solutions for the color-flavor locked strangelets
Prof. Guang Xiong Peng, Xin Jian Wen and Yuede Chen (2005)
A paper reporting that the charge of color-flavor locked strangelets can be positive, negative, or
nearly neutral.
http://arxiv.org/abs/hep-ph/0512112
see also:
http://arxiv.org/abs/hep-ph/0612253

 

Maybe rpenner will consider your query? That would be cool. Anyway ..... Looking at the cite base for both papers I noted that 0612253 is cited, [13], in this review of LHC safety. Page 9.
http://arxiv.org/abs/0806.3414
So the authors of the review include the results from 0612253 in the analysis. rpenner is an expert on the LHC safety details. Which I now realize rpenner has already made a comment.

 

I don't see his comment. Once again total layman just looking for some information to calm myself against those whom create fear and worry

 

The pentaquark is a very rare, unstable ( \( \Gamma^{-1} \approx 1.7 \times 10^{-23} \, \textrm{s}\) ) resonance involving massively unstable ( \( \Gamma^{-1} \approx 2.0 \times 10^{-13} \, \textrm{s, based on} \, \Lambda_{c}^{+}\)) heavy charmed quarks and antiquarks. The corresponding phenomena seems unrelated to even potential stabilization of strange quark matter when strange quarks are also unstable ( \( \Gamma^{-1} \approx 2.6 \times 10^{-10} \, \textrm{s, based on} \, \Lambda^{0}\)) and it seems unlikely that the mechanism that stabilizes down ( \( \Gamma^{-1} \approx 8.8 \times 10^{+2} \, \textrm{s, based on} \, n\)) quarks in some nuclei is one that will scale to span the greater mass difference.

In other words, a rare instability 13 orders of magnitude less stable than naked strange quarks is not conceivably related to a hypothetical mechanism for suppressing strange decay in a manner similar to neutrons, 13 orders of magnitude more stable. Extrapolation over 25-26 orders of magnitude isn't justified by any relevant calculation.

In addition to the facts that color-flavor locked strangelets are first order approximations to bulk matter in a realm where analytic continuous matter distributions have not had much success and that even Peng's model says the ground state (most stable solution) of strangelets is positive, and therefore non-dangerous, these models are speculative in the extreme with respect to small baryon numbers, and small baryon numbers is exactly what heavy ion fireballs get you.

Finally, the valance quarks of the pentaquark are 4 of matter and 1 of anti-matter. Antimatter doesn't make your bound system more stable.