5,830 research outputs found
Efimov Physics around the neutron rich Calcium-60 isotope
We calculate the neutron-Calcium-60 S-wave scattering phase shifts using
state of the art coupled-cluster theory combined with modern ab initio
interactions derived from chiral effective theory. Effects of three-nucleon
forces are included schematically as density dependent nucleon-nucleon
interactions. This information is combined with halo effective field theory in
order to investigate the Calcium-60-neutron-neutron system. We predict
correlations between different three-body observables and the two-neutron
separation energy of Calcium-62. This provides evidence of Efimov physics along
the Calcium isotope chain. Experimental key observables that facilitate a test
of our findings are discussed.Comment: 5 pages, 4 figure
The Outburst of the Blazar AO 0235+164 in 2006 December: Shock-in-Jet Interpretation
We present the results of polarimetric ( band) and multicolor photometric
() observations of the blazar AO 0235+16 during an outburst in 2006
December. The data reveal a short timescale of variability (several hours),
which increases from optical to near-IR wavelengths; even shorter variations
are detected in polarization. The flux density correlates with the degree of
polarization, and at maximum degree of polarization the electric vector tends
to align with the parsec-scale jet direction. We find that a variable component
with a steady power-law spectral energy distribution and very high optical
polarization (30-50%) is responsible for the variability. We interpret these
properties of the blazar withina model of a transverse shock propagating down
the jet. In this case a small change in the viewing angle of the jet, by
, and a decrease in the shocked plasma compression by a factor of
1.5 are sufficient to account for the variability.Comment: 22 pages, 8 figures, accepted for Ap
The Stellar Content of the Polar Rings in the Galaxies NGC 2685 and NGC 4650A
We present the results of stellar photometry of polar-ring galaxies NGC 2685
and NGC 4650A, using the archival data obtained with the Hubble Space
Telescope's Wide Field Planetary Camera 2. Polar rings of these galaxies were
resolved into ~800 and ~430 stellar objects in the B, V and Ic bands,
considerable part of which are blue supergiants located in the young stellar
complexes. The stellar features in the CM-diagrams are best represented by
isochrones with metallicity Z = 0.008. The process of star formation in the
polar rings of both galaxies was continuous and the age of the youngest
detected stars is about 9 Myr for NGC 2685 and 6.5 Myr for NGC 4650A.Comment: 21 pages, 9 figures, AJ 2004 February, accepte
New Gauge Invariant Formulation of the Chern-Simons Gauge Theory
A new gauge invariant formulation of the relativistic scalar field
interacting with Chern-Simons gauge fields is considered. This formulation is
consistent with the gauge fixed formulation. Furthermore we find that canonical
(Noether) Poincar\'e generators are not gauge invariant even on the constraints
surface and do not satisfy the (classical) Poincar\'e algebra. It is the
improved generators, constructed from the symmetric energy-momentum tensor,
which are (manifestly) gauge invariant and obey the classical Poincar\'e
algebra.Comment: Shortened, to appear as Papid Communication-PRD/Nov/9
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