1,996 research outputs found
Magnetic tape transport controlled by rotating transducer heads
Magnetic tape transport includes a common drive for both the tape drive capstans and the rotating record/reproduce heads. Speed of the drive may be varied within a preselected range, but, once selected, remains constant so head and capstan are driven in synchronization and at constant speed
A Model for Dark Matter Halos
A halo model is presented which possesses a constant phase space density (Q)
core followed by a radial CDM-like power law decrease in Q. The motivation for
the core is the allowance for a possible primordial phase space density limit
such as the Tremaine-Gunn upper bound. The space density profile derived from
this model has a constant density core and falls off rapidly beyond. The new
model is shown to improve the fits to the observations of LSB galaxy rotation
curves, naturally provides a model which has been shown to result in a
lengthened dynamical friction time scale for the Fornax dwarf spheroidal galaxy
and predicts a flattening of the density profile within the Einstein radius of
galaxy clusters. A constant gas entropy floor is predicted whose adiabatic
constant provides a lower limit in accord with observed galaxy cluster values.
While `observable-sized' cores are not seen in standard cold dark matter (CDM)
simulations, phase space considerations suggest that they could appear in warm
dark matter (WDM) cosmological simulations and in certain hierarchically
consistent SuperWIMP scenarios.Comment: 14 pages, 3 figures, accepted for publication in Ap
Exotic dynamically generated baryons with C1
We follow a model based on the SU(8) symmetry for the interaction of mesons
with baryons. The model treats on an equal footing the pseudo-scalars and the
vector mesons, as required by heavy quark symmetry. The T-matrix calculated
within an unitary scheme in coupled channels has poles which are interpreted as
baryonic resonances.Comment: 5 pages. Proceedings for Chiral10 workshop, Valencia, June 21-24 201
Non-Abelian Chern-Simons-Higgs vortices with a quartic potential
We have constructed numerically non-Abelian vortices in an SU(2)
Chern-Simons-Higgs theory with a quartic Higgs potential. We have analyzed
these solutions in detail by means of improved numerical codes and found some
unexpected features we did not find when a sixth-order Higgs potential was
used. The generic non-Abelian solutions have been generated by using their
corresponding Abelian counterparts as initial guess. Typically, the energy of
the non-Abelian solutions is lower than that of the corresponding Abelian one
(except in certain regions of the parameter space). Regarding the angular
momentum, the Abelian solutions possess the maximal value, although there exist
non-Abelian solutions which reach that maximal value too. In order to classify
the solutions it is useful to consider the non-Abelian solutions with
asymptotically vanishing component of the gauge potential, which may be
labelled by an integer number . For vortex number and above, we have
found uniqueness violation: two different non-Abelian solutions with all the
global charges equal. Finally, we have investigated the limit of infinity Higgs
self-coupling parameter and found a piecewise Regge-like relation between the
energy and the angular momentum.Comment: 9 pages, 13 figure
Electromagnetic structure and weak decay of pseudoscalar mesons in a light-front QCD-inspired model
We study the scaling of the meson mass splitting and the
pseudoscalar weak decay constants with the mass of the meson, as seen in the
available experimental data. We use an effective light-front QCD-inspired
dynamical model regulated at short-distances to describe the valence component
of the pseudoscalar mesons. The experimentally known values of the mass
splittings, decay constants (from global lattice-QCD averages) and the pion
charge form factor up to 4 [GeV/c] are reasonably described by the modelComment: 27 Pages, 7 eps figures,use revtex
Odd Parity Light Baryon Resonances
We use a consistent SU(6) extension of the meson-baryon chiral Lagrangian
within a coupled channel unitary approach in order to calculate the T-matrix
for meson-baryon scattering in s-wave. The building blocks of the scheme are
the pion and nucleon octets, the rho nonet and the Delta decuplet. We identify
poles in this unitary T-matrix and interpret them as resonances. We study here
the non exotic sectors with strangeness S=0,-1,-2,-3 and spin J=1/2, 3/2 and
5/2. Many of the poles generated can be associated with known N, Delta, Sigma,
Lambda and Xi resonances with negative parity. We show that most of the
low-lying three and four star odd parity baryon resonances with spin 1/2 and
3/2 can be related to multiplets of the spin-flavor symmetry group SU(6). This
study allows us to predict the spin-parity of the Xi(1620), Xi(1690), Xi(1950),
Xi(2250), Omega(2250) and Omega(2380) resonances, which have not been
determined experimentally yet.Comment: New appendix and references adde
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