Effect Of Pair Creation Research Articles

Effects of pair creation on the expansion of vacuum bubbles

The real-time behavior of true-vacuum bubbles nucleated in the false-vacuum background is studied in a λϕ 4 theory. Classically, the bubble expansion rate has been known to approach the velocity of light asymptotically. A quantum effect, creation of Higgs and fermion pairs, is studied by a semiclassical method, and is shown to lead to a slower expansion rate. Within the thin-wall approximation, several possible asymptotic behaviors are examined. A solution that behaves like the classical one but with different coefficients is shown to be stable. The first-order corrections to the coefficients are calculated approximately. The created Higgs pairs are found to remain inside the bubble and carry an energy of approximately 10 −3 λ of the energy released from the false vacuum. The fermions that are massless in the false vacuum go out of the bubble and have energy ∼10 −3 g 2, where g is the Yukawa coupling constant. It is shown that the resulting asymptotic state is Lorentz invariant.

Even more about gauge theories in 1 + 1 dimensions

It is shown that the properly defined background electric field in 1 + 1 dimensional quantum electrodynamics is not limited in magnitude by pair creation effects. Furthermore, the inequivalence of the axial gauge and the Coulomb gauge is pointed out. Applications to quantum chromodynamics are discussed.

Some problems of pulsar physics or I'm madly in love with electricity

Some current topics in the theory of pulsar magnetospheres and their emission are reviewed. The mode of plasma supply and its consequences for structure of planetary and stellar magnetospheres is discussed. In the pulsar case, the plasma is supplied by electrical forces, in contrast to all other known examples. The resulting theories of particle acceleration along polar field lines are then reviewed, and the total energization of the charge separated plasma is summarized, when pair creation is absent. The effects of pair creation are reviewed using models of the resulting steady and unsteady flows, when the polar zones of the pulsar emit either electrons or ions. The application of these theories of acceleration and plasma supply to pulsars is discussed, with particular attention paid to the total amount of electron-positron plasma created and its momentum distribution. Qualitative agreement is shown between the spatial structure of the relativistically outflowing plasma described in one version of these models and the morphology of pulsar wave forms. Various aspects of radiation emission and transport are summarized, based on the polar current flow model with pair creation, and the phenomenon of marching subpulses is discussed. The corotation beaming and the relativistically expanding current sheet models for pulsar emission are also discussed briefly, and the paper concludes with a brief discussion of the relation between the theories of polar flow with pair plasma and the problem of the energization of the Crab Nebula.

Contrast in computerized transverse axial tomography of brain

A study of 'contrast' in photon transmission tomography of the brain is presented. Quantitative evaluation of linear attenuation coefficients due to photoelectric. Compton and pair creation effects suggests that the use of photons of a few MeV considerably improves the contrast between white and grey brain matter. The patient dose at different photon energies is calculated.

Problem of Intense Magnetic Field in Gravitational Collapse

Electron Dirac and Schwinger magnetic moments behavior in magnetic fields during gravitational collapse, discussing electron pair creation effects