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Albion
2010-Jun-01, 04:51 PM
A proton is comprised of two ups and a down quark of color red green and blue. When two protons are slammed together under pressure (in a star), how do those two protons "stick" together? Does the green quark in one proton combine using the strong force with the blue and red quark from the other proton? After the slamming together of two protons does one always decay to a neutron or do some of the proton proton combinations just break apart?

Secondly, the charm quark was found by locating a charm/anti-charm quark pair at 3.11 GeV. How can this be if the charm/anti-charm pair only add up to 2.54 GeV?

Thanks

trinitree88
2010-Jun-02, 03:30 PM
A proton is comprised of two ups and a down quark of color red green and blue. When two protons are slammed together under pressure (in a star), how do those two protons "stick" together? Does the green quark in one proton combine using the strong force with the blue and red quark from the other proton? After the slamming together of two protons does one always decay to a neutron or do some of the proton proton combinations just break apart?

Secondly, the charm quark was found by locating a charm/anti-charm quark pair at 3.11 GeV. How can this be if the charm/anti-charm pair only add up to 2.54 GeV?

Thanks

Albion. Good question.The proton is more than the three quarks. There are also colored gluons shuttling around exchanging the color force in quantum chromodynamics inside it's confines...(and slightly "outside"). So when they collide, the interaction is not just quark on quark, it's pretty messy, and is sometimes referred to as "hot quark soup". During the interaction, jets occur, with mesons and leptons created along with the charm/anticharm pair. So the energy you need in the collision for effective charm/anticharm production exceeds the rest-mass/energy in Mev/c2 by the average amount of messy side products (mesons/leptons) also produced. That's known as branching channels, and the hot quark soup has several different modes to interact in. The extra 0.57 Gev fills the bill for the debris in the interaction zone.
This is why they need to do multiple runs to refine their estimates of the rest masses of particles. Sometimes they have overlooked additional branching channels that use the energy of interaction. Eventually, their algorithms yield converging values for their data, and the confidence levels improve. As a theorist, I love the first indications of new stuff, but would go bonkers spending years refining the data. However, experimentalists need to be sure that they're not claiming confidence beyond their actual data, and happily carve out careers finding ever more precise information. Such is life in the world of physics, and ever will be. Pete

Albion
2010-Jun-04, 02:47 PM
Thanks!

That's exactly what I was looking for.

-Al

BigDon
2010-Jun-05, 09:46 PM
Of course as a layman of casual education all I heard from Trini's reply was something very much like a half overheard lecture at Hogwart's. :)