
LHCb experiment reports observation of exotic pentaquark particles - suprgeek
http://press.web.cern.ch/press-releases/2015/07/cerns-lhcb-experiment-reports-observation-exotic-pentaquark-particles
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filmor
The two most interesting links from the article:

\- [http://lhcb-public.web.cern.ch/lhcb-
public/Welcome.html#Pent...](http://lhcb-public.web.cern.ch/lhcb-
public/Welcome.html#Penta) (LHCb website)

\- [http://arxiv.org/abs/1507.03414](http://arxiv.org/abs/1507.03414) (paper)

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ChikkaChiChi
Will this have an impact on the Standard Model? If so, does this have any
ramifications on proving or disproving any particular quantum theories?

~~~
jessriedel
No. This is analogous to finding a new molecule in chemistry, or a new isotope
in nuclear physics. None of the fundamental constituents are different,
they've just been been combined in a new way. (In fairness, this combination
is a lot more novel than most new molecules or isotopes.) In principle, the
existence of these pentaquarks could have been definitively calculated from
first principles if we had sufficient computing power, just as for all
molecules, but this is infeasible.

~~~
ISL
It's more than that; the mass and properties of a pentaquark will tell us a
lot about the underlying properties of the strong force. People have been
trying to predict the pentaquark masses and lifetimes for many years.

Computations of low-energy strong-force interactions are significantly more
difficult than electromagnetism. As far as I know, the proton binding energy
has not yet been calculated with confidence, though it should happen in the
next decade or two.

If the result holds up, this will count as one of LHC's major discoveries.

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betatim
A little history on previous pentaquark discoveries
[http://link.springer.com/article/10.1140%2Fepjh%2Fe2012-2003...](http://link.springer.com/article/10.1140%2Fepjh%2Fe2012-20032-0)

~~~
jcr
Unfortunately, that paper is pay-walled by springer.com.

On the bright side, the author of that paper, Kenneth H. Hicks, has provided
three different explanations of pentaquarks here:

[http://plato.phy.ohiou.edu/~hicks/thplus.html](http://plato.phy.ohiou.edu/~hicks/thplus.html)

They are a bit dated due to the news today, but they're helpful.

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espinchi
> "More precisely the states must be formed of two up quarks, one down quark,
> one charm quark and one anti-charm quark."

It blows my mind

~~~
ars
I find most interesting that the charm and anti-charm do not annihilate. That
would not happen with non-quark particles.

~~~
wickedshimmy
They can annihilate -- but annihilation channels are OZI-suppressed because of
gluon effects in e.g. charmonium (the J/psi, a famously narrow resonance,
which was one of the final states of the decay that produced this signal). The
same mechanism is likely in play here as well (it is an artifact of QCD) --
the idea is that hadronization can be energetically favorable to annihilation:
since the gluons carry a strong charge (color), they participate in the
interaction and can nucleate a light q/q-bar pair rather than requiring an
additional (virtual) gluon to couple to the annihilation vertex.

(Also it does happen with non-quark particles as well! Positronium for
example, is an electron-positron bound states -- we just see more stable
hadron particles like this because QCD has Weird Maths).

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lucianp
I think the submission should link to the actual press release:
[http://press.web.cern.ch/press-releases/2015/07/cerns-
lhcb-e...](http://press.web.cern.ch/press-releases/2015/07/cerns-lhcb-
experiment-reports-observation-exotic-pentaquark-particles)

~~~
dang
Ok, URL changed from
[http://www.interactions.org/cms/?pid=1034868](http://www.interactions.org/cms/?pid=1034868),
which is a copy of this.

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naturalethic
Whatever

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soulsurfer
Ingress Agents already know that as exotic matter (XM) ;-)

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Create
people at cern have forgotten long ago:

“Scientists study the world as it is, engineers create the world that never
has been.” – Theodore von Kármán

Gell Mann and Zweig among others proposed the imaginary concept of quarks (or
partons, Feynman's Dolly) to do something about all those particles that kept
popping up in accelerators. There was a time, when a particle was a run-of-
the-mill cookie-cutter thesis.

~~~
Coding_Cat
And before that, water was made out of "water", wood was made out of "wood",
and the world was a much simpler place. Your point being?

