Particle-antiparticle pairs

Other examples of ether are a superfluid of particle-antiparticle pairs [92], a fluid of stuff particles [26], and a variety of fluids [93-97]. From such fluids, electrodynamic and particle models easily follow see Thomson [98], Hofer [99], Marmanis [100], and Dmitriyev [101]. 

What can be tested As mentioned before, CPT invariance guarantees the equality of masses, charges and lifetimes of particles and antiparticles. This means that the experimental investigations of masses, charges, etc. of particle - antiparticle pairs are tests of CPT symmetry. Such experiments are not easy to do with the charged particles themselves (because of their interactions with stray fields). Comparison of neutral atom - antiatom pairs is much more convenient. In particular, the fine structure, hyperfine structure and Lamb shifts of atoms and antiatoms should be identical - and can be tested in laboratory. 

Positronium, being a readily available purely leptonic system and also a particle-antiparticle pair, has attracted considerable experimental interest over the years as a testing ground for the existence of exotic particles or couplings. The latter may perhaps manifest themselves in the decay properties of positronium, so that attempts have been made to observe forbidden modes. In particular, the longstanding discrepancy between the Michigan experimental value for oAo-ps and the results from QED calculations, described in subsection 7.1.1, has acted as a spur to such investigations. 

Consider, for example a finite number of fermion or particle-antiparticle pairs in a vacuum or particle-like environment as defined in Eq. (18) (cf. Cooper pairs in a superconductor. Using Eqs. (22) and (23), we obtain for the associated (many-body potential) energy... 

The reaction of Eq. (3.6.15) is also possible in the reverse direction, even if relatively infrequent this is particle-antiparticle pair creation. This possibility is what underlies the idea of vacuum polarization and small effects, like the Lamb shift in atomic spectra. Positrons are not that rare Many radioactive nuclei decay by positron emission—for instance, sodium-22 ... 

Electron-positron and proton-antiproton are particle-antiparticle pairs in which the members of each pair have the same masses but opposite charges. The neutrino and antineutrino are neutral particles that form another important particle-antiparticle pair. 

There is another alternative to SBBN which, although currently less favored, does have a venerable history BBN in the presence of a background of degenerate neutrinos. First, a brief diversion to provide some perspective. In the very early universe there were a large number of particle-antiparticle pairs of all kinds. As the baryon-antibaryon pairs... 

Giving a rigorous account of relativistic effects is now an important goal in theoretical and experimental studies because of recent progress made in experimental techniques and because of the accuracy currently achievable in measurements, e.g. in atomic and molecular spectroscopy, or in view of newly available laser techniques. Present accessible energies in heavy-ion accelerators allow a new generation of experiments with ultrarelativistic ions, which, for example, enable us to probe the structure of the vacuum via the electromagnetic particle-antiparticle pair creation. 

Indeed, as already pointed out, a relativistic theory describes both a particle and its antiparticle so that only the total charge of the system is conserved but not the number of particles. For physical systems in which no particle-antiparticle pairs are created we should add a constraint to take this fact into account. We shall elaborate more on this point in the next section. 

In this way all contributions to and 7 resulting from the virtual creation of particle-antiparticle pairs in the Furry picture defined by the KS potential (63) are suppressed. 

It is evident that self-organization and the emergence of dissipative structures on a Liouvillian meso-macroscopic level seem to support the use of general Jordan forms. At the same time, on the microscopic domain, we have pointed out the possibility to model (i) particle-antiparticle pairs via... 

Interaction with the vacuum (Fig. 3.5a). In contemporary physics theory, the perfect vacuum does not just represent nothing. The electric field of the vacuum itself fluctuates about zero and these instantaneous fluctuations influence the motion of any chaiged particle. When a strong electric field operates in a vacuum, the latter undeigoes a polarization (called vacuum polarizfition), which means a spontaneous creation of matter, and more specifically, of particle-antiparticle pairs. 

Table 3.1. Contributions of various physical effects (non-relativistic, Bieit, QED, and beyond QED, distinct physical contributions shown in bold) to the ionization energy and the dipole polarizability a of the helium atom, as well as comparison with the experimental values (all quantities are expressed in atomic units i.e.. e = 1. fi = 1, mo = 1- where iiiq denotes the rest mass of the electron). The first column gives the symbol of the term in the Breit-Pauli Hamiltonian [Eq. (3.72)] as well as of the QED corrections given order by order (first corresponding to the electron-positron vacuum polarization (QED), then, beyond quantum electrodynamics, to other particle-antiparticle pairs (non-QED) li,7T,. ..) split into several separate effects. The second column contains a short description of the effect. The estimated error (third and fourth columns) is given in parentheses in the units of the last figure reported. 

What about the creation of other (than e-p) particle-antiparticle pairs from the vacuum the larger the rest mass is, the more difficult it is to squeeze out the corresponding particle-antiparticle pair. And yet we have some tiny effect (see non-QED entry) corresponding to the creation of such pairs as muon-antimuon (jx), pion-antipion (tt), etc. This means that the helium atom is composed of the nucleus and the two electrons only, when we look at it within a certain approximation. To tell the truth, the atom contains also photons, electrons, positrons, muons, pions, and whatever you wish, but with a smaller and smaller probability of appearance. All that has only a minor effect of the order of something like the seventh significant figure (both for the ionization potential and for the polarizability). 

Hawking process Emission of particles by a black hole as a result of quantum-mechanical effects. The process was first suggested by Stephen Hawking. The gravitational field of the black hole causes production of particle-antiparticle pairs in the... 

At moderate energies photons do not interact with each other. A propagating photon can, however, convert into a (virtual) particle-antiparticle pair for very short times and distances as... 

Proton-nucleus collisions at high energies (5-20 GeV) create particle-antiparticle pairs, which then can be separated by charge in a magnetic field. (In particle physics, the usual units are GeV = lO eV for energy E, GeV/c for momentum p, and GeV/c for mass m. When expressed in natural units with h = I and c = 1, one gets for the total energy if = + rrf.)... 

Figure 2.2 A gas of electrons and positrons in equilibrium with radiation at very high temperatures. At temperatures over 10 K, particle-antiparticle pair creation and annihilation begins to occur and the total number of particles is no longer a constant. At these temperatures, electrons, positrons and photons are in the state called thermal radiation. The energy density of thermal radiation depends only on the temperature...

When we consider interconversion of particles and radiation, as in the case of particle-antiparticle pair creation and annihilation, the chemical potential of thermal photons becomes more significant (Fig. 11.4). Consider thermal photons in equilibrium with electron-positron pairs ... 

For reasons of symmetry we may assert that (ie+ = Pg-. Since = 0 we must conclude that for particle-antiparticle pairs that can be created by thermal photons Pe = Pe- = 0. 

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