3,127 research outputs found
Highly charged ions: optical clocks and applications in fundamental physics
Recent developments in frequency metrology and optical clocks have been based
on electronic transitions in atoms and singly charged ions as references. These
systems have enabled relative frequency uncertainties at a level of a few parts
in . This accomplishment not only allows for extremely accurate time
and frequency measurements, but also to probe our understanding of fundamental
physics, such as variation of fundamental constants, violation of the local
Lorentz invariance, and forces beyond the Standard Model of Physics. In
addition, novel clocks are driving the development of sophisticated technical
applications. Crucial for applications of clocks in fundamental physics are a
high sensitivity to effects beyond the Standard Model and Einstein's Theory of
Relativity and a small frequency uncertainty of the clock. Highly charged ions
offer both. They have been proposed as highly accurate clocks, since they
possess optical transitions which can be extremely narrow and less sensitive to
external perturbations compared to current atomic clock species. The selection
of highly charged ions in different charge states offers narrow transitions
that are among the most sensitive ones for a change in the fine-structure
constant and the electron-to-proton mass ratio, as well as other new physics
effects. Recent advances in trapping and sympathetic cooling of highly charged
ions will in the future enable high accuracy optical spectroscopy. Progress in
calculating the properties of selected highly charged ions has allowed the
evaluation of systematic shifts and the prediction of the sensitivity to the
"new physics" effects. This article reviews the current status of theory and
experiment in the field.Comment: 53 pages, 16 figures, submitted to RM
Enhancement of the electric dipole moment of the electron in PbO
The a(1) state of PbO can be used to measure the electric dipole moment of
the electron d_e. We discuss a semiempirical model for this state, which yields
an estimate of the effective electric field on the valence electrons in PbO.
Our final result is an upper limit on the measurable energy shift, which is
significantly larger than was anticipated earlier: .Comment: 4 pages, revtex4, no figures, submitted to PR
The Bose-Einstein correlation function from a Quantum Field Theory point of view
We show that a recently proposed derivation of Bose-Einstein correlations
(BEC) by means of a specific version of thermal Quantum Field Theory (QFT),
supplemented by operator-field evolution of the Langevin type, allows for a
deeper understanding of the possible coherent behaviour of the emitting source
and a clear identification of the origin of the observed shape of the BEC
function . Previous conjectures in this matter obtained by other
approaches are confirmed and have received complementary explanation.Comment: Some misprints corrected. To be publishe in Phys. Rev.
Antonio de Alfián y Juan de Oviedo el Viejo. El retablo de la Inmaculada de la Parroquia de Santa Ana de Sevilla (1573-1574)
En este artículo se documenta el retablo concertado conjuntamente por el pintor Antonio de Alfián y el entallador
Juan de Oviedo el Viejo para el altar de Melchor de Horozco en la parroquia sevillana de Santa Ana. Del retablo sólo
se han conservado en la actualidad las pinturas que formaron parte del conjunto, pinturas que, a pesar de haber sido
atribuidas a diversos pintores, nunca se habían vinculado con el estilo de Alfián. A partir del estudio de éstas, es posible
atribuirle otras obras, algunas de las cuales analizamos.This paper examines the painted and carved altarpiece made by the painter Antonio de Alfián and the “entallador”
Juan de Oviedo the Elder for Melchor de Horozco in the parish church of Santa Ana in Seville. Only the paintings,
however, are preserved. Never before linked to this master, these paintings allow a more complete understanding of Alfián’s
somewhat unknown style. Thanks to the documentation of the altarpiece, it is now possible to attribute other
works to this painter, some of which we study
Using Molecules to Measure Nuclear Spin-Dependent Parity Violation
Nuclear spin-dependent parity violation arises from weak interactions between
electrons and nucleons, and from nuclear anapole moments. We outline a method
to measure such effects, using a Stark-interference technique to determine the
mixing between opposite-parity rotational/hyperfine levels of ground-state
molecules. The technique is applicable to nuclei over a wide range of atomic
number, in diatomic species that are theoretically tractable for
interpretation. This should provide data on anapole moments of many nuclei, and
on previously unmeasured neutral weak couplings
Some forgotten features of the Bose Einstein Correlations
Notwithstanding the visible maturity of the subject of Bose-Einstein
Correlations (BEC), as witnessed nowadays, we would like to bring to ones
attention two points, which apparently did not received attention they deserve:
the problem of the choice of the form of correlation function when
effects of partial coherence of the hadronizing source are to be included and
the feasibility to model effects of Bose-Einstein statistics, in particular the
BEC, by direct numerical simulations.Comment: Talk delivered by G.Wilk at the International Workshop {\it
Relativistic Nuclear Physics: from Nuclotron to LHC energies}, Kiev, June
18-22, 2007, Ukraine; misprints correcte
Analysis of Structure Destroyed Metal after Diffusion Heat Treatment
It was accomplished research of the structure steel which carbonitriding and subsequent heat treatment was exposed for its cause's destruction to discover. For measure quality field of metal were used methods optical, appearing electronic microscopy and X-ray diffraction. Therefore one of the principal problems were research phase composition, grain and dislocation structure of a metal the gear teeth. Mechanism of rising hear cracks in the gear teeth on different stages her making and their trajectories of evolution were determined
Enhancement of the electric dipole moment of the electron in BaF molecule
We report results of ab initio calculation of the spin-rotational Hamiltonian
parameters including P- and P,T-odd terms for the BaF molecule. The ground
state wave function of BaF molecule is found with the help of the Relativistic
Effective Core Potential method followed by the restoration of molecular
four-component spinors in the core region of barium in the framework of a
non-variational procedure. Core polarization effects are included with the help
of the atomic Many Body Perturbation Theory for Barium atom. For the hyperfine
constants the accuracy of this method is about 5-10%.Comment: 8 pages, REVTEX, report at II International Symposium on Symmetries
in Subatomic Physics, Seattle 199
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