
Семинар 20 июня 2017. В. А. Березин. Phenomenology of cosmological particle creation, Dirac sea and all that.
20 июня 2017, в 12:45 Кафедра физики высоких энергий и элементарных частиц В. А. Березин (ИЯИ РАН, Москва) Phenomenology of cosmological particle creation, Dirac sea and all that Here we present a phenomenological model of cosmological particle creation which allows to avoid the "vicious circle" when the purely quantum treatment of the fields, which quanta are just the created particle, requires imposing definite boundary conditions, while the latter, in turn, requires solving the gravitational equations with the created particles together with the expectation values of these very fields as their source. We are using the hydrodynamical description of the created particles (in Eulerian coordinates) incorporating the "creation law" straight into the action integral with the corresponding Lagrange multiplier. Adopting the famous result that the particle production rate is proportional to the square of the Weyl tensor, we showed that this induces the appearance of conformal gravity action integral. It was tempting, then, to demand the local conformal invariance as the fundamental law. Such a requirement, as was shown, has very fargoing consequences. It concerns, first of all, the scalar field (terribly needed in the Standard Model). Writing for the scalar field the simplest possible action (kinetic + mass terms only) we showed that the local conformal invariance requires introduction of the curvature scalar and, at the same time, the identification of this field with one of the possible conformal factors, and such an identification induces the selfinteraction arising from the mass term and playing the role of the quintessence. Thus, we have got the WeylEinstein  dilaton gravity with the cosmological term almost for nothing. Then, we considered the vacuum equations in our model. It is shown that, beside the "empty vacuum" (i.e., no particles and no particle creation) which is rather poor, there may exist the "dynamical vacuum" when particle with both positive and negative energies are continuously creating leaving the total energymomentum tensor zero. This is just the Dirac sea. The vacuum equations in this case are especially nice  the linear combination of the Bach tensor, the Einstein tensor and the cosmological constant.
Отправлено Thu, 15 Jun 2017 02:16:17 +0400
