Where is the Cosmic Antimatter?
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Matter and antimatter are basically almost identical (but for their opposite charges). How come there is practically no antimatter in the Universe? If matter and antimatter were once equally abundant, how come they did not annihilate each other? How come we are here? The baryon (proton plus neutron) to photon ratio. Ribbons in the sky? Almost complete annihilation.Keywords:
Annihilation
Our universe could be the mirror image of an antimatter universe extending backwards in time before the Big Bang. So claim physicists in Canada.
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We present some initial results of a detailed calculation of the cosmological $\ensuremath{\gamma}$-ray spectrum from matter-antimatter annihilation in the universe. The similarity of the calculated spectrum with the present observations of the $\ensuremath{\gamma}$-ray background spectrum above 1 MeV suggests that such observations may be evidence of the existence of antimatter on a large scale in the universe.
Annihilation
Scale factor (cosmology)
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We have studied big bang nucleosynthesis in the presence of regions of antimatter. Depending on the distance scale of the antimatter region, and thus the epoch of their annihilation, the amount of antimatter in the early universe is constrained by the observed abundances. Small regions, which annihilate after weak freezeout but before nucleosynthesis, lead to a reduction in the ${}^{4}\mathrm{He}$ yield, because of neutron annihilation. Large regions, which annihilate after nucleosynthesis, lead to an increased ${}^{3}\mathrm{He}$ yield. Deuterium production is also affected but not as much. The three most important production mechanisms of ${}^{3}\mathrm{He}$ are (1) photodisintegration of ${}^{4}\mathrm{He}$ by the annihilation radiation, (2) ${p}^{4}\mathrm{He}$ annihilation, and (3) ${n}^{4}\mathrm{He}$ annihilation by ``secondary'' antineutrons produced in ${}^{4}\overline{\mathrm{He}}$ annihilation. Although ${p}^{4}\mathrm{He}$ annihilation produces more ${}^{3}\mathrm{He}$ than the secondary ${n}^{4}\mathrm{He}$ annihilation, the products of the latter survive later annihilation much better, since they are distributed further away from the annihilation zone. Our results are in qualitative agreement with similar work by Rehm and Jedamzik, but we get a larger ${}^{3}\mathrm{He}$ yield.
Annihilation
Photodisintegration
Big Bang nucleosynthesis
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The means of detecting the presence of antimatter in the universe are discussed. Both direct, annihilation processes, and indirect, cosmic ray particles, were analyzed. All results were negative and it was concluded that no antimatter exists, if the universe is in fact symmetric. If the universe is not symmetric then matter and antimatter are well separated from each other.
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We introduce a new dynamical group whose coadjoint action on its momentum space takes account of matter-antimatter symmetry on pure geometrical grounds. According to this description the energy and the spin are unchanged under matter-antimatter symmetry. We recall that the antichron components of the Poincaré group, ruling relativistic motions of a mass-point particle, generate negative energy particles. The model with two twin universes, inspired by Sakharov's one, solves the stability issue. Positive and negative energy particles motions hold in two distinct folds. The model is extended to charged particles. As a result, the matter-antimatter duality holds in both universes.
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The universe we see gives every sign of being composed of matter. This is considered a major unsolved problem in theoretical physics. Using the mathematical modeling based on the algebra ${\bf{T}} := {\bf{C}}\otimes{\bf{H}}\otimes{\bf{O}}$, an interpretation is developed that suggests that this seeable universe is not the whole universe; there is an unseeable part of the universe composed of antimatter galaxies and stuff, and an extra 6 dimensions of space (also unseeable) linking the matter side to the antimatter - at the very least.
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In this paper, Diract equation solutions are discussed in quantum field theory. It is our viewthat vacuum can be defined as sea that be filled with pairs of negative energy electron and postiveenergy positron and pairs of negative energy position and positive energy electron. According to theexact experiments that position mass is 0.998 times as heavy as electron mass, we assume thatnegative energy position in vacuum can be translated to position electron in universe When it onlyabsorb positive energy, which is two times as big as that of electric energy. Proton is also thus, or invacuum negative energy proton and antiproton can be translated to proton and antiproton in universeif it only absorb positive energy, which is two times as big as that of it electric energy. In this paper,we construct matter and antimatter symmetric universe model basing on this paper, supposition, and itexplain the origin of universe in essence comparing with well-known big burst universe model.
Negative mass
Antiproton
Zero-energy universe
Antiparticle
Negative energy
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We consider a simple model in which the matter-antimatter asymmetry of the universe is brought about by an effective two-particle interaction that violates baryon-number conservation as well as $\mathrm{CP}$ invariance. The particle fields participating in the interaction are quantized, and their time development in an isotropically expanding universe is found to all orders in the coupling constant. Pair production by the asymmetric interaction, as well as symmetric production by the gravitational field of the expanding universe, appear simultaneously in the solution. Taking an initial state in which no particles participating in the asymmetric interaction are present, we find the created baryon-number density. We consider in more detail the case when the matter-antimatter asymmetry is produced during a stage when the radius of the universe is small with respect to its present value. We make numerical estimates of the created matter-antimatter asymmetry, and put limits on possible values of the parameters of this model.
Baryon asymmetry
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Matter-antimatter annihilation is discussed as a means of rocket propulsion. The feasibility of different means of antimatter storage is shown to depend on how annihilation rates are affected by various circumstances. The annihilation processes are described, with emphasis on important features of atom-antiatom interatomic potential energies. A model is developed that allows approximate calculation of upper and lower bounds to the interatomic potential energy for any atom-antiatom pair. Formulae for the upper and lower bounds for atom-antiatom annihilation cross-sections are obtained and applied to the annihilation rates for each means of antimatter storage under consideration. Recommendations for further studies are presented.
Annihilation
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