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Nucleon constituents

by mathman
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mathman
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Jan15-13, 03:35 PM
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I understand that nucleons (protons and neutrons) consist of 3 valence quarks and a sea of other stuff, virtual quark-antiquark pairs and gluons. Question: are the virtual quarks only up and down or may there be heavier quarks?
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fzero
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Jan15-13, 08:05 PM
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Quote Quote by mathman View Post
I understand that nucleons (protons and neutrons) consist of 3 valence quarks and a sea of other stuff, virtual quark-antiquark pairs and gluons. Question: are the virtual quarks only up and down or may there be heavier quarks?
All flavors contribute because of [itex]g\leftrightarrow q\bar{q}[/itex] processes. A quick search didn't turn up any sort of canonical reference, but http://cerncourier.com/cws/article/cern/29441 explains some experimental measurements related to the strange component of the proton.
mfb
#3
Jan16-13, 09:12 AM
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This pdg review has (predicted) parton distribution functions on page 12. Heavier quarks are suppressed, but they are present.

mathman
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Jan16-13, 03:38 PM
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Nucleon constituents

Quote Quote by fzero View Post
All flavors contribute because of [itex]g\leftrightarrow q\bar{q}[/itex] processes. A quick search didn't turn up any sort of canonical reference, but http://cerncourier.com/cws/article/cern/29441 explains some experimental measurements related to the strange component of the proton.
I would guess that it is possible that the other heavier quarks may be present, but the experiments might be difficult. Maybe LHC might find something?
Bill_K
#5
Jan16-13, 03:55 PM
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Naturally if you hit a proton hard enough, heavy quarks will be produced. I thought your question was, is there a significant percentage of heavy quarks already in the proton. And to answer this, as described in the ref, you want to do low energy experiments with high accuracy.
mathman
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Jan17-13, 03:27 PM
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Quote Quote by Bill_K View Post
Naturally if you hit a proton hard enough, heavy quarks will be produced. I thought your question was, is there a significant percentage of heavy quarks already in the proton. And to answer this, as described in the ref, you want to do low energy experiments with high accuracy.
My confusion is how do you tell what was there already as compared to what happens when protons collide with something.
mfb
#7
Jan18-13, 09:05 AM
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With simulations - you cannot "see" this directly in detectors, you can just compare (statistical) experimental results with the simulated results.


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