The word "annihilation" takes use informally for the interaction of two particles that are not mutual antiparticles – not charge conjugate. High-energy particle colliders produce annihilations where a wide variety of exotic heavy particles are created. ĭuring a low-energy annihilation, photon production is favored, since these particles have no mass. Hence, any set of particles may be produced whose total quantum numbers are also zero as long as conservation of energy, conservation of momentum, and conservation of spin are obeyed. Antiparticles have exactly opposite additive quantum numbers from particles, so the sums of all quantum numbers of such an original pair are zero. The total energy and momentum of the initial pair are conserved in the process and distributed among a set of other particles in the final state. Whereas the decay to two photons via a virtual top quark loop is only 0.2%, it is a distinct, clean signature in the detectors, and is carefully studied.In particle physics, annihilation is the process that occurs when a subatomic particle collides with its respective antiparticle to produce other particles, such as an electron colliding with a positron to produce two photons. The Higgs to WW or ZZ is via a virtual Higgs, since both of these pairs are more massive than a real Higgs at 125 GeV. The tau lepton has a mass of 1.8 GeV, and the charm (c) quark has a mass of 1.5 GeV, so these are next among the fermion-antifermion pairs. The next heaviest quark is the bottom at 4.2 GeV, so it decays to a pair of bottom (b) and anti-bottom quarks. The 125 GeV Higgs discovered is too light to decay to a pair of top (t) and anti-top quarks. The decay of a Higgs at 125 GeV is proportioned into the following channels: So a virtual particle of Mc^2 = 100 GeV can exist to transit about 2/1,000 of the size of a proton.) The distance that they can traverse is (h c)/(2 pi M c^2) or about (0.2 GeV f)/(Mc^2), where f is a fermi = 10^(-13) cm, and is about the diameter of a proton. (Virtual particles do not have the perfect combination of energy and momentum to become real particles, and exist by the Heisenberg Uncertainty Principal over times that are roughly h/(2 pi M c^2) where h is Planck’s constant and M is the mass of the virtual particle. At the mass of the detected Higgs at 125 GeV, the gluon gluon fusion is dominant, and the quark-quark and quark-antiquark collisions are about a tenth of that rate. In the lower right, a virtual W or Z boson decays to a real W or Z boson, respectively, with a real Higgs also. The ones that produce the Higgs are virtual, the escaping ones are real. In the lower left, gluons each produce a pair of top and anti-top quarks. The upper right is the creation and fusion of oppositely charged W’s to a neutral Higgs, or of neutral Z bosons to a Higgs. The upper left diagram is the fusion of gluons to produce a virtual top quark loop, which then produces a real Higgs. These are the dominant processes because the Higgs couples proportional to a particles’ mass, and favors the most massive particles which are the top quark at 174 GeV, the W boson at 80 GeV, and the Z boson at 91 GeV. The final particles are all real particles. In W or Z bremsstrahlung the intermediate W or Z are virtual. Here are Feynman diagrams of the various Higgs production processes. The quarks can also emit virtual W bosons, leading to a Higgs production process called W boson fusion. The main constituents are the valence quarks, the virtual gluons that they emit, and the quark-antiquark pairs that are formed from the virtual gluons, which also include strange and anti-strange quarks. This is called Feynman’s x, after Richard Feynman’s insightful treatment of parton kinematics and dynamics. However, each component of the proton or “parton” has its own distribution function of momentum as a function of its fraction ‘x’ of the proton’s momentum. So the final 14 TeV center of mass energy collisions might only produce new particles up to 5 TeV in mass or 2.5 TeV in pairs. At a high fraction of the proton’s momentum, a rule of thumb is to say that each valence quark might have about a third of the proton’s momentum to use in hard elementary particle collisions to produce a massive particle. Each proton has two valence up quarks and one valence down quark. First of all, the protons circulating in the LHC have to be considered as a bag of quark and gluon components.
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