5,219 research outputs found
On Dimensional Degression in AdS(d)
We analyze the pattern of fields in d+1 dimensional anti-de Sitter space in
terms of those in d dimensional anti-de Sitter space. The procedure, which is
neither dimensional reduction nor dimensional compactification, is called
dimensional degression. The analysis is performed group-theoretically for all
totally symmetric bosonic and fermionic representations of the anti-de Sitter
algebra. The field-theoretical analysis is done for a massive scalar field in
AdS(d+d) and massless spin one-half, spin one, and spin two fields in
AdS(d+1). The mass spectra of the resulting towers of fields in AdS(d) are
found. For the scalar field case, the obtained results extend to the shadow
sector those obtained by Metsaev in [1] by a different method.Comment: 30 page
Hyperfine structure of S-states in muonic deuterium
On the basis of quasipotential method in quantum electrodynamics we calculate
corrections of order and to hyperfine structure of S-wave
energy levels of muonic deuterium. Relativistic corrections, effects of vacuum
polarization in first, second and third orders of perturbation theory, nuclear
structure and recoil corrections are taken into account. The obtained numerical
values of hyperfine splitting meV (1S state) and
meV (2S state) represent reliable estimate for a
comparison with forthcoming experimental data of CREMA collaboration. The
hyperfine structure interval meV can be used for precision check of quantum
electrodynamics predictions for muonic deterium.Comment: 18 pages, 7 figure
Exploring the S-Matrix of Massless Particles
We use the recently proposed generalised on-shell representation for
scattering amplitudes and a consistency test to explore the space of tree-level
consistent couplings in four-dimensional Minkowski spacetime. The extension of
the constructible notion implied by the generalised on-shell representation,
i.e. the possibility to reconstruct at tree level all the scattering amplitudes
from the three-particle ones, together with the imposition of the consistency
conditions at four-particle level, allow to rediscover all the known theories
and their algebra structure, if any. Interestingly, this analysis seems to
leave room for high-spin couplings, provided that at least the requirement of
locality is weakened. We do not claim to have found tree-level consistent
high-spin theories, but rather that our methods show signatures of them and
very likely, with a suitable modification, they can be a good framework to
perform a systematic search.Comment: 44 pages, 1 figur
Radiative nonrecoil nuclear finite size corrections of order to the Lamb shift in light muonic atoms
On the basis of quasipotential method in quantum electrodynamics we calculate
nuclear finite size radiative corrections of order to the
Lamb shift in muonic hydrogen and helium. To construct the interaction
potential of particles, which gives the necessary contributions to the energy
spectrum, we use the method of projection operators to states with a definite
spin. Separate analytic expressions for the contributions of the muon
self-energy, the muon vertex operator and the amplitude with spanning photon
are obtained. We present also numerical results for these contributions using
modern experimental data on the electromagnetic form factors of light nuclei.Comment: 8 pages, 1 Figur
DETRITAL ZIRCON AGES AND SOURCES OF MATERIAL FOR THE LOWER CAMBRIAN DEPOSITS OF THE MEL'GIN TROUGH OF THE BUREYA CONTINENTAL MASSIF
Bureya continental massif is one of the largest continental massifs in the eastern part of the Central Asian orogenic belt (CAOB) (Fig. 1), and knowledge of its geological structure is of fundamental importance in understanding the history of its formation.Bureya continental massif is one of the largest continental massifs in the eastern part of the Central Asian orogenic belt (CAOB) (Fig. 1), and knowledge of its geological structure is of fundamental importance in understanding the history of its formation
Multiple ionization of neon by soft X-rays at ultrahigh intensity
At the free-electron laser FLASH, multiple ionization of neon atoms was
quantitatively investigated at 93.0 eV and 90.5 eV photon energy. For ion
charge states up to 6+, we compare the respective absolute photoionization
yields with results from a minimal model and an elaborate description. Both
approaches are based on rate equations and take into acccout a Gaussian spatial
intensity distribution of the laser beam. From the comparison we conclude, that
photoionization up to a charge of 5+ can be described by the minimal model. For
higher charges, the experimental ionization yields systematically exceed the
elaborate rate based prediction.Comment: 10 pages, 3 figure
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