187 research outputs found
Comment on "Quantum entropy and special relativity" [by A. Peres, P. F. Scudo, and D. R. Terno, Phys. Rev. Lett. 88, 230402 (2002)]
Two subtleties of this paper are discussed.Comment: version probably to appear in Phys. Rev. Letter
Why and how to use a differential equation method to calculate multi-loop integrals
A short pedagogical introduction to a differential method used to calculate
multi-loop scalar integrals is presented. As an example it is shown how to
obtain, using the method, large mass expansion of the two loop sunrise master
integrals.Comment: 9 p., presented at XXV International Conference on Theoretical
Physics "Particle Physics and Astrophysics in the Standard Models and
Beyond", Ustron, Poland, September 200
Automatic regularization by quantization in reducible representations of CCR: Point-form quantum optics with classical sources
Electromagnetic fields are quantized in manifestly covariant way by means of
a class of reducible representations of CCR. transforms as a Hermitian
four-vector field in Minkowski four-position space (no change of gauge), but in
momentum space it splits into spin-1 massless photons (optics) and two massless
scalars (similar to dark matter). Unitary dynamics is given by point-form
interaction picture, with minimal-coupling Hamiltonian constructed from fields
that are free on the null-cone boundary of the Milne universe. SL(2,C)
transformations and dynamics are represented unitarily in positive-norm Hilbert
space describing four-dimensional oscillators. Vacuum is a Bose-Einstein
condensate of the -oscillator gas. Both the form of and its
transformation properties are determined by an analogue of the twistor
equation. The same equation guarantees that the subspace of vacuum states is,
as a whole, Poincar\'e invariant. The formalism is tested on quantum fields
produced by pointlike classical sources. Photon statistics is well defined even
for pointlike charges, with UV/IR regularizations occurring automatically as a
consequence of the formalism. The probabilities are not Poissonian but of a
R\'enyi type with . The average number of photons occurring in
Bremsstrahlung splits into two parts: The one due to acceleration, and the one
that remains nonzero even if motion is inertial. Classical Maxwell
electrodynamics is reconstructed from coherent-state averaged solutions of
Heisenberg equations. Static pointlike charges polarize vacuum and produce
effective charge densities and fields whose form is sensitive to both the
choice of representation of CCR and the corresponding vacuum state.Comment: 2 eps figures; in v2 notation in Eq. (39) and above Eq. (38) is
correcte
- …