The Naked Scientists-June 2012

After lunch there was a discussion group with Dr Jonathon Hays. Proton mass comes from the strong force. Energy stored gets bigger and bigger as the quarks are moved apart. If it can become big enough more quarks are produced. If energy is left over you get mass. If the Higgs hadn’t been discovered it might have meant that fundamental particles weren’t fundamental. On average 3 quarks will result in a proton or neutron being formed. The quarks which determine the quantum numbers of hadrons are called valence quarks; apart from these, any hadron may contain an indefinite number of virtual (or sea) quarks, antiquarks, and gluons which do not influence its quantum numbers.
There are two families of hadrons: baryons, with three valence quarks, and mesons, with a valence quark and an antiquark.
The most common baryons are the proton and the neutron, the building blocks of the atomic nucleus. Van der Waals forces are attractive or repulsive forces between molecules. Gluons are the forces between quarks. A neutron can decay into a proton but not vice versa unless a proton interacts with a photon but if the neutron is in the nucleus with a proton, the proton can decay. Neutron numbers have to increase with increasing proton number (in larger nuclei) to stop the nucleus breaking apart due to proton repulsion. Higher and higher energies are required to probe a nucleus. At lower energies it appears like a solid sphere.

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