How Pentaquarks May Lead To the Discovery of New Fundamental Physics

StartsWithABang writes: Over 100 years ago, Rutherford's gold foil experiment discovered the atomic nucleus. At higher energies, we can split that nucleus apart into protons and neutrons, and at still higher ones, into individual quarks and gluons. But these quarks and gluons can combine in amazing ways: not just into mesons and baryons, but into exotic states like tetraquarks, pentaquarks and even glueballs. As the LHC brings these states from theory to reality, here's what we're poised to learn, and probe, by pushing the limits of quantum chromodynamics.

Comments

Re:ask slashdot

[Anonymous Coward]

How does this relate to string theory ?

It doesn't.

This is real science.

Actually, you CAN'T do that

[wonkey_monkey]

At higher energies, we can split that nucleus apart into protons and neutrons, and at still higher ones, into individual quarks

In one sense that seems to be something you really can't do. The force between free quarks increases with distance to about 10,000N, then remains constant (no, I have no idea how this makes any sense, but it's what I read). Any force sufficient to tear two quarks apart is sufficient to generate new quarks which then bind with the "free" quarks. So you never see quarks by themselves.

IANAP, though. Does the above really mean that if you had two free quarks separated by a kilometre or a light year, that there would still be that constant 10,000N force between them?

Re:Actually, you CAN'T do that

[Carewolf]

At higher energies, we can split that nucleus apart into protons and neutrons, and at still higher ones, into individual quarks

In one sense that seems to be something you really can't do. The force between free quarks increases with distance to about 10,000N, then remains constant (no, I have no idea how this makes any sense, but it's what I read). Any force sufficient to tear two quarks apart is sufficient to generate new quarks which then bind with the "free" quarks. So you never see quarks by themselves.

IANAP, though. Does the above really mean that if you had two free quarks separated by a kilometre or a light year, that there would still be that constant 10,000N force between them?

Plus that we are not even sure quarks are individual things. They might just be eigenvalues of particle properties, nice to calculate on, but not necessarily anything real in themselves.

Re:Actually, you CAN'T do that

[K. S. Kyosuke]

Any force sufficient to tear two quarks apart is sufficient to generate new quarks which then bind with the "free" quarks.

Sounds like the War on Terrorism in a microscopic edition. Fractal universe confirmed!

Re:Actually, you CAN'T do that

[Anonymous Coward]

The top quark can exist without hadronizing, so the properties of "naked" quarks can be studied. Not sure if just an eigenvector can explain that.

Re:Actually, you CAN'T do that

[fizassist]

In one sense that seems to be something you really can't do. The force between free quarks increases with distance to about 10,000N, then remains constant (no, I have no idea how this makes any sense, but it's what I read).

IAAP, and you can "separate" a nucleon into constituent quarks in a sense. You're right in that you can't take them a kilometer apart because of the range behavior of the strong nuclear force that you cite. Instead, you create extremely high energy density region that makes the nucleons lose their identity, and the constituent quarks are free to interact with each other (a Quark-Gluon Plasma). This is done by colliding heavy ions, which creates a high energy density region that has some extent to it (as opposed to proton-proton collisions). The quarks can then "condense" out of this plasma into exotic things like pentaquarks.

Re:Actually, you CAN'T do that

[ceoyoyo]

You can't ever get two quarks very far apart. That property arises because the gluon, the force carrier for the strong force, has a strong charge of it's own. That's as if photons were electrically charged. When two quarks exchange virtual gluons the gluons exchange virtual gluons with everything around as well. The bigger the distance between the quarks, the more space for colour charged gluons between them, so the stronger the force.

When you pull two quarks further and further apart, at some point it's energetically favourable for a couple of virtual quarks to pop into existence and you end up with a couple of mesons instead of two free quarks. That's what happens in accelerators: nobody ever sees quarks, they see sprays of particles that indicate a hadron was blown apart and the constituent quarks then reformed into hadrons.

It's called colour confinement: https://en.wikipedia.org/wiki/...

Re:Actually, you CAN'T do that

[Anonymous Coward]

"You can't ever get two quarks very far apart. That property arises because the gluon, the force carrier for the strong force, has a strong charge of it's own. "

If you tried to separate "it" from "is", will the force generate new apostrophes?

Re:Actually, you CAN'T do that

[ultranova]

The force between free quarks increases with distance to about 10,000N, then remains constant (no, I have no idea how this makes any sense, but it's what I read).

According to Wikipedia it's because gluons, which mediate the Strong Force interaction between quarks, also feel said force themselves (that is, they carry color charge(. So rather than disperse with distance like, say, photons do, they tend to stick together and form "ropes".

So it's analogous to how a flashlight loses power faster than a laser.

Re:Actually, you CAN'T do that

[Khashishi]

What is a real individual thing? In the end, if we can model it and we can measure it, it's about as real as anything in our world can be.

Re:Actually, you CAN'T do that

[hawkfish]

"You can't ever get two quarks very far apart. That property arises because the gluon, the force carrier for the strong force, has a strong charge of it's own. "

If you tried to separate "it" from "is", will the force generate new apostrophes?

Pedantry AND wit - what is /. coming to?

Re:Actually, you CAN'T do that

[HiThere]

No, because sometimes several different models will fit all the available information. E.g., I prever the EGW multi-world interpretation of quantum physics, but the Copenhagen interpretation fits all the data just as well, and so do a few others...including such useless ones as "SuperPredestinationsim", "Solipsism", and "God is doing at all, and fudges things whenever he notices you're doing an experiment".

Re:Actually, you CAN'T do that

[Spinalcold]

Interpretations of QM's is not science since they can not be tested (as of yet, I hope it can be some day). However the different models of atoms can and have been tested very well and QCD's has fit the data to an amazing precision. I'm sure there are competing theories but I have never heard of any that fit the data this well. btw, I'm a fan of the many worlds interpretation as well. Took me a long time to come around to it, thought it was just a curiosity at first, but eventually I saw the beauty of it. You don't need to add anything else to QMs it just pops right out of the science.

Re:Actually, you CAN'T do that

[TheTurtlesMoves]

IAAP and your mostly correct. However the force is no where near 10kN. However lets assume 1N, with 1m of seperation that is 1J of energy. Or enough energy to produce about a billion protons. So yea true separation distance are small before more quarks are created.

Re:Actually, you CAN'T do that

[tehcyder]

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Your ideas are intriguing to me and I wish to subscribe to your newsletter.

Re:Actually, you CAN'T do that

[smaddox]

The Everettian interpretation is certainly better than the Copenhagen interpretation, since it doesn't raise the measurement problem; however, it's no where near as simple (in the Occam's razor sort of way) as the Bohmian interpretation.

However, I think the history of physics should teach us that different interpretations are often different facets of the same thing. Compare Lagrangian and Hamiltonian mechanics, for example. They are both accurate (at least for our universe), but quite different in their approach and interpretation. However, they are unified in that they are dependent on conservation laws. A unified theory should be approachable from both directions, and possibly other directions as well. It also turns out that one is often easier to apply than the other in certain situations, and thus both approaches are useful.

Perhaps there is a bit of truth in each of the QM interpretations.

Not a summary

[dinfinity]

This is not a summary, but a teaser. Let's keep that kind of bullshit off Slashdot.

Actual summary:
"Recently, the existence of pentaquarks, predicted by quantum chromodynamics, was confirmed. This sortof validates quantum chromodynamics. [Intro to quantum chromodynamics]. We could find many more particles predicted by quantum chromodynamics in the future!"

Re:Not a summary

[NoNonAlphaCharsHere]

It's really irritating when you read these articles where the authors treat hypothetical particles and real particles interchangeably, worse when you get tables full of them intermixed.

Re:Not a summary

[tomxor]

...where the authors treat hypothetical particles and theoretical particles interchangeably...

FTFY

Re:Not a summary

[LaurenCates]

You got your hypothesis in my theory!

You got your theory in my hypothesis!

Alas, the end result isn't a Reese's cup.

Re:Not a summary

[cgold]

Scientists discover pentaquarks, and what happens next will blow your mind!

Re:Not a summary

[Coren22]

Mmmm Reese's.

Darn you!

Re:Not a summary

[Spinalcold]

This is a 9 Sigma result, far FAR higher than the Higgs. The summary is stating that exotic matter does exist but we don't know what kinds. Can glueballs exist? What other combinations are out there to be found?

Re:ask slashdot

[donaggie03]

Based on the the fact you called GP a "denier moron" it makes me wonder if you understand what the A in AGW stands for.

Re:ask slashdot

[LaurenCates]

Or maybe string cheese theory?

Mmmmm...string cheese...

Re:ask slashdot

[donaggie03]

Turns out it was *I* who didn't know what the A stood for. When I replied to your post I was thinking it stood for 'Anti' as in Anti-global-warming. Add that to the fact you called GP a denier moron and you can see my confusion. Note my emphasis was on your use of the word denier, not moron.

Re:Anyone know why this moron does this?

[hackwrench]

Some researcher connected a cow's brain to the internet and gave it a Slashdot account.

Re:Quantum Chromodynamics

[Anonymous Coward]

So the fuck what?

Re:A is for anthropocentric.

[hackwrench]

Like "Soylent Green is people" I thought everyone knew that.
http://muppet.wikia.com/wiki/F...

Re:Anyone know why this moron does this?

[Foobar of Borg]

Some researcher connected a cow's brain to the internet and gave it a Slashdot account.

Well, that would explain the editors...

Re:ask slashdot

[donaggie03]

Ok. I hope you feel better now.

I read all the words

[raxtich]

..but I have no idea what any of it means.

Re:Pentaquarks are for five cows.

[Killall -9 Bash]

THERE ARE NOT 5 QUARKS, BUT 20 QUARKS ROTATING THROUGH 4 24-HOUR DAYS IN THE 4 CORNER CUBE EARTH. SCIENCE EDUCATES YOU STUPID. YOU BELIEVE IN CHILD-KILLER GOD PARTICLE. LEAVE CHILD ALONE IN ROOM WITH GOD PARTICLE; CHILD DIES OF STARVATION. YOU CAN'T UNDERSTAND 20 QUARKS BECAUSE YOU THINK 1+1=2 INSTEAD OF 1+1=8. THIS IS WHY GOD EATS YOUR CHILDREN AND SHITS YOUR 5 QUARKS INTO SCHOOL KIDS FROM THE SCHOOLTEACHER'S DIRTY MOUTH.

Gadgets

[ChrisMaple]

Early discoveries and hypotheses on small stuff have led to immense improvements in chemistry and electronics, and the development of nuclear power. Is there even a hint of a notion that this sort of work is going to lead to something practical? If so, what?

Re:Anyone know why this moron does this?

[tehcyder]

Some researcher connected a cow's brain to the internet and gave it a Slashdot account.

Well, that would explain the editors...

Bit harsh on cows though.

"Individual Quarks"

[Pope Raymond Lama]

TFS lost me right there. There is No Such Thing(tm)