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If matter and antiMatter will annihilate each other after coming into contact,how can a meson come into existence?
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Matter-antiMatter annihilation,Mesons?
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Mesons are made up of a quark and an antiquark, and have a temporary existence, in the same way that positronium exists temporarily. A neutral pion, for example, self-annihilates into two photons in 10-16 sec. "Charmonium", a combination of a charmed quark and antiquark, is especially interesting because it can exist in several well-defined states analogous to atomic levels.
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It is also very misleading to say "matter and antimatter annihilate each other!" Remember that there are MANY types of antimatter. Antielectrons, anti-up quarks, etc.
So if you have a bound state made up of a down quark and an anti-strange quark (the simplest example being a meson called a "Kaon"), then the down and anti-strange quarks will NOT annihilate each other, despite the matter and antimatter nature of the particles! What happens instead is that the strange quark in the Kaon will decay.
Strictly speaking, I should say that the PROBABILITY of Kaon decay through annihilation is vanishingly small. So "annihilation" is not the only (or most important) way for mesons to decay.
So if you have a bound state made up of a down quark and an anti-strange quark (the simplest example being a meson called a "Kaon"), then the down and anti-strange quarks will NOT annihilate each other, despite the matter and antimatter nature of the particles! What happens instead is that the strange quark in the Kaon will decay.
Strictly speaking, I should say that the PROBABILITY of Kaon decay through annihilation is vanishingly small. So "annihilation" is not the only (or most important) way for mesons to decay.
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You mean for example just a pair of up quark and antiquark will annihilate each other?
Or the above annihilation is the most probable?
Or the above annihilation is the most probable?
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Shyan said:
an up - anti-up quark bound state is (for example) the neutral pion - the quarks there will annihilate into 2 photons. This is the dominant channel for the neutral pion to decay.
You can compute the time it will take this annihilation to happen from the time the meson is formed - this is the "lifetime" of the particle. The computed time agrees excellently with experiment.
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No,I meant,Do you mean that only quark-antiquark pairs which of the same type annihilate?The example being up-antiup quark pair.
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Shyan said:
to leading order, yes. it turns out that different quarks can annihilate each other, but it must go through a quantum correction, which makes it a much rarer event, and therefore much less important.
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Your post was just disappointing iam.You really could explain.
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Its my first time encountering one of them and also hearing your second sentence.What does it mean?Is it a proverb or idiom or sth?
smith345
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Antiparticles look and behave just like their corresponding matter particles, except they have opposite charges. For instance, a proton is electrically positive whereas an antiproton is electrically negative. Gravity affects matter and antimatter the same way because gravity is not a charged property and a matter particle has the same mass as its antiparticle.
smith345
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antiparticles are produced in pairs in high-energy proton-antiproton collisions. This computer representation shows the decay products of the short-lived candidate particle produced in a collision. The decay products are used to identify the B_s mesons produced in the collision. (Courtesy of DZero collaboration)
