2,866 research outputs found
Cold Collision Frequency Shift in Two-Dimensional Atomic Hydrogen
We report a measurement of the cold collision frequency shift in atomic
hydrogen gas adsorbed on the surface of superfluid 4He at T<=90 mK. Using
two-photon electron and nuclear magnetic resonance in 4.6 T field we separate
the resonance line shifts due to the dipolar and exchange interactions, both
proportional to surface density sigma. We find the clock shift Delta v_c =
-1.0(1)x10^-7 Hz cm^-2 x sigma, which is about 100 times smaller than the value
predicted by the mean field theory and known scattering lengths in the 3D case.Comment: 4 pages, 3 figure
Parent formulation at the Lagrangian level
The recently proposed first-order parent formalism at the level of equations
of motion is specialized to the case of Lagrangian systems. It is shown that
for diffeomorphism-invariant theories the parent formulation takes the form of
an AKSZ-type sigma model. The proposed formulation can be also seen as a
Lagrangian version of the BV-BRST extension of the Vasiliev unfolded approach.
We also discuss its possible interpretation as a multidimensional
generalization of the Hamiltonian BFV--BRST formalism. The general construction
is illustrated by examples of (parametrized) mechanics, relativistic particle,
Yang--Mills theory, and gravity.Comment: 26 pages, discussion of the truncation extended, typos corrected,
references adde
On the Irreducible BRST Quantization of Spin-5/2 Gauge Fields
Spin-5/2 gauge fields are quantized in an irreducible way within both the
BRST and BRST-anti-BRST manners. To this end, we transform the reducible
generating set into an irreducible one, such that the physical observables
corresponding to these two formulations coincide. The gauge-fixing procedure
emphasizes on the one hand the differences among our procedure and the results
obtained in the literature, and on the other hand the equivalence between our
BRST and BRST-anti-BRST approaches.Comment: 12 pages, latex 2.09, no figure
BTZ Black Hole as Solution of 3d Higher Spin Gauge Theory
BTZ black hole is interpreted as exact solution of 3d higher spin gauge
theory. Solutions for free massless fields in BTZ black hole background are
constructed with the help of the star-product algebra formalism underlying the
formulation of 3d higher spin theory. It is shown that a part of higher spin
symmetries remains unbroken for special values of the BTZ parameters.Comment: 31 pages, LaTeX; references correcte
Euler-Calogero-Moser system from SU(2) Yang-Mills theory
The relation between SU(2) Yang-Mills mechanics, originated from the
4-dimensional SU(2) Yang-Mills theory under the supposition of spatial
homogeneity of the gauge fields, and the Euler-Calogero-Moser model is
discussed in the framework of Hamiltonian reduction. Two kinds of reductions of
the degrees of freedom are considered: due to the gauge invariance and due to
the discrete symmetry. In the former case, it is shown that after elimination
of the gauge degrees of freedom from the SU(2) Yang-Mills mechanics the
resulting unconstrained system represents the ID_3 Euler-Calogero-Moser model
with an external fourth-order potential. Whereas in the latter, the IA_6
Euler-Calogero-Moser model embedded in an external potential is derived whose
projection onto the invariant submanifold through the discrete symmetry
coincides again with the SU(2) Yang-Mills mechanics. Based on this connection,
the equations of motion of the SU(2) Yang-Mills mechanics in the limit of the
zero coupling constant are presented in the Lax form.Comment: Revtex, 14 pages, no figures. Abstract changed, strata analysis have
been included, typos corrected, references adde
Families of exact solutions to Vasiliev's 4D equations with spherical, cylindrical and biaxial symmetry
We provide Vasiliev's four-dimensional bosonic higher-spin gravities with six
families of exact solutions admitting two commuting Killing vectors. Each
family contains a subset of generalized Petrov Type-D solutions in which one of
the two so(2) symmetries enhances to either so(3) or so(2,1). In particular,
the spherically symmetric solutions are static and we expect one of them to be
gauge-equivalent to the extremal Didenko-Vasiliev solution given in
arXiv:0906.3898. The solutions activate all spins and can be characterized
either via generalized electric and magnetic charges defined asymptotically in
weak-field regions or via the values of fully higher-spin gauge-invariant
observables given by on-shell closed zero-forms. The solutions are obtained by
combining the gauge-function method with separation of variables in twistor
space via expansion of the Weyl zero-form in Di-Rac supersingleton projectors
times deformation parameters in a fashion that is suggestive of a generalized
electromagnetic duality.Comment: v1: 77 pages; 3 tables; 23 pages of appendices. v2: 5 additional
pages of clarifications, typos correcte
Radioactive contamination of ZnWO4 crystal scintillators
The radioactive contamination of ZnWO4 crystal scintillators has been
measured deep underground at the Gran Sasso National Laboratory (LNGS) of the
INFN in Italy with a total exposure 3197 kg x h. Monte Carlo simulation,
time-amplitude and pulse-shape analyses of the data have been applied to
estimate the radioactive contamination of the ZnWO4 samples. One of the ZnWO4
crystals has also been tested by ultra-low background gamma spectrometry. The
radioactive contaminations of the ZnWO4 samples do not exceed 0.002 -- 0.8
mBq/kg (depending on the radionuclide), the total alpha activity is in the
range: 0.2 - 2 mBq/kg. Particular radioactivity, beta active 65Zn and alpha
active 180W, has been detected. The effect of the re-crystallization on the
radiopurity of the ZnWO4 crystal has been studied. The radioactive
contamination of samples of the ceramic details of the set-ups used in the
crystals growth has been checked by low background gamma spectrometry. A
project scheme on further improvement of the radiopurity level of the ZnWO4
crystal scintillators is briefly addressed.Comment: 15 pages, 8 figures, 6 tables, submitted for publicatio
Guiding and Trapping Electron Spin Waves in Atomic Hydrogen Gas
We present a high magnetic field study of electron spin waves in atomic
hydrogen gas compressed to high densities of 10^18 cm^-3 at temperatures
ranging from 0.26 to 0.6 K. We observed a variety of spin wave modes caused by
the identical spin rotation effect with strong dependence on the spatial
profile of the polarizing magnetic field. We demonstrate confinement of these
modes in regions of strong magnetic field and manipulate their spatial
distribution by changing the position of the field maximum.Comment: 5 pages, 4 figure
Alternative commutation relations, star products and tomography
Invertible maps from operators of quantum obvservables onto functions of
c-number arguments and their associative products are first assessed. Different
types of maps like Weyl-Wigner-Stratonovich map and s-ordered quasidistribution
are discussed. The recently introduced symplectic tomography map of observables
(tomograms) related to the Heisenberg-Weyl group is shown to belong to the
standard framework of the maps from quantum observables onto the c-number
functions. The star-product for symbols of the quantum-observable for each one
of the maps (including the tomographic map) and explicit relations among
different star-products are obtained. Deformations of the Moyal star-product
and alternative commutation relations are also considered.Comment: LATEX plus two style files, to appear in J. Phys.
Proceedings of the third French-Ukrainian workshop on the instrumentation developments for HEP
The reports collected in these proceedings have been presented in the third
French-Ukrainian workshop on the instrumentation developments for high-energy
physics held at LAL, Orsay on October 15-16. The workshop was conducted in the
scope of the IDEATE International Associated Laboratory (LIA). Joint
developments between French and Ukrainian laboratories and universities as well
as new proposals have been discussed. The main topics of the papers presented
in the Proceedings are developments for accelerator and beam monitoring,
detector developments, joint developments for large-scale high-energy and
astroparticle physics projects, medical applications.Comment: 3rd French-Ukrainian workshop on the instrumentation developments for
High Energy Physics, October 15-16, 2015, LAL, Orsay, France, 94 page
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