![]() AntiprotonĪs was written, a particle and its antiparticle have the same mass as one another but opposite electric charge and other differences in quantum numbers. There is currently no experimental evidence that proton decay occurs. It must be added some theories have suggested that protons are, in fact, unstable with a very long half-life (~10 30years) and that they decay into leptons. Thus, the decay would violate the conservation of the baryon number. Since the proton is the lightest particle among all baryons, the hypothetical products of its decay would have to be non-baryons. This principle provides the basis for the stability of the proton. ![]() On the other hand, the following reaction (proton-antiproton pair production) does conserve B and does occur if the incoming proton has sufficient energy (the threshold energy = 5.6 GeV):Īs indicated, B = +2 on both sides of this equation.įrom these and other reactions, the conservation of the baryon number has been established as a basic principle of physics. This reaction does not conserve the baryon number since the left side has B =+2, and the right has B =+1. The sum of the baryon number of all incoming particles is the same as the sum of the baryon numbers of all particles resulting from the reaction.įor example, the following reaction has never been observed:Įven if the incoming proton has sufficient energy and charge energy and is conserved. The law of conservation of baryon number states that: Baryon number is a generalization of nucleon number, conserved in non-relativistic nuclear reactions and decays. The decay of proton is also associated with the law of conservation of baryon number. Free protons are found naturally in many situations (e.g., they make up 90% of cosmic rays) in which energies or temperatures are high enough to separate them from electrons, for which they have some affinity. The free proton (a proton not bound to nucleons or electrons) is a stable particle that has not been observed to break down spontaneously to other particles. It must be noted that gluons are inherently massless and possess energy. Mass is primarily a measure of the energies of the quark motion and the quark-binding fields of any real object. Noteworthy, because most of your mass is due to the protons and neutrons in your body, your mass (and therefore your weight on a bathroom scale) comes primarily from the gluons that bind the constituent quarks together rather than from the quarks themselves. The quarks of the neutron are held together by gluons, the exchange particles for the strong nuclear force. Like the proton, most of the mass (energy) of the neutron is in the form of the strong nuclear force energy (gluons). The mass of the proton is 938.272 MeV/c 2, whereas the mass of the three quarks is only about 12 MeV/c 2 (only about 1% of the mass-energy of the neutron). The proton has a quark composition of uud, and so its charge quantum number is: This fundamental interaction governs the behavior of the quarks that make up the individual protons and neutrons. Protons and neutrons are bound together within the nucleus through a strong force. Inside the protons and neutrons, we find true elementary particles called quarks. ![]() Protons and neutrons also have their structure.
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