3,309 research outputs found
A nu=2/5 Paired Wavefunction
We construct a wavefunction, generalizing the well known Moore-Read Pfaffian,
that describes spinless electrons at filling fraction nu=2/5 (or bosons at
filling fraction nu=2/3) as the ground state of a very simple three body
potential. We find, analogous to the Pfaffian, that when quasiholes are added
there is a ground state degeneracy which can be identified as zero-modes of the
quasiholes. The zero-modes are identified as having semionic statistics. We
write this wavefunction as a correlator of the Virasoro minimal model conformal
field theory M(5,3). Since this model is non-unitary, we conclude that this
wavefunction is a quantum critical state. Nonetheless, we find that the
overlaps of this wavefunction with exact diagonalizations in the lowest and
first excited Landau level are very high, suggesting that this wavefunction may
have experimental relevance for some transition that may occur in that regime.Comment: 13 pages, 2 figure
The Pulsation Mode and Distance of the Cepheid FF Aquilae
The determination of pulsation mode and distance for field Cepheids is a
complicated problem best resolved by a luminosity estimate. For illustration a
technique based on spectroscopic luminosity discrimination is applied to the
4.47d s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable
yield values of =-3.40+-0.02 s.e.(+-0.04 s.d.), average effective
temperature Teff=6195+-24 K, and intrinsic color (-)o = +0.506+-0.007,
corresponding to a reddening of E(B-V)=0.25+-0.01, or E(B-V)(B0)=0.26+-0.01.
The skewed light curve, intrinsic color, and luminosity of FF Aql are
consistent with fundamental mode pulsation for a small amplitude classical
Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A
distance of 413+-14 pc is estimated from the Cepheid's angular diameter in
conjunction with a mean radius of =39.0+-0.7 Rsun inferred from its
luminosity and effective temperature. The dust extinction towards FF Aql is
described by a ratio of total-to-selective extinction of
Rv=Av/E(B-V)=3.16+-0.34 according to the star's apparent distance modulus.Comment: To appear in ApJ
Initial-state nuclear effects in proton-nucleus collisions
Two important initial-state nuclear effects in hadron-nucleus collisions are
considered. The ratios of inclusive differential cross sections for Drell-Yan
dimuon production are calculated. The calculated results are compared to the
E866 data. It is shown that consideration of multiple soft rescatterings of
incident quarks in nuclei and initial-state quark energy loss effects allow to
get a good agreement between the calculated results and the experimental data.Comment: 6 pages, 6 figure
Rate of Period Change as a Diagnostic of Cepheid Properties
Rate of period change for a Cepheid is shown to be a parameter that
is capable of indicating the instability strip crossing mode for individual
objects, and, in conjunction with light amplitude, likely location within the
instability strip. Observed rates of period change in over 200 Milky Way
Cepheids are demonstrated to be in general agreement with predictions from
stellar evolutionary models, although the sample also displays features that
are inconsistent with some published models and indicative of the importance of
additional factors not fully incorporated in models to date.Comment: Published in PASP (March 2006); TeX source & figures now provide
Dimethyl dichloromalonate as a new synthetic equivalent of methyl dichloroacetate in the Darzens condensation
Dimethyl dichloromalonate reacts with aldehydes in the presence of sodium methoxide to form α-chloropyruvates, α-chloroglycidates, or α,α-dichlorohydrins, depending on the nature of the aldehyde. © 1995, Plenum Publishing Corporation. All rights reserved
Reactions of allenylphosphonates with 1,2-diaminoethane
The reactions of dialkyl 3-methylbuta-1,2-dien-1-ylphosphonates with 1,2-diaminoethane lead to the formation of symmetrical N,NâČ-bis(1- dialkoxyphosphoryl-3-methylbut-1-en-2-yl)-1,2-diaminoethanes. © 2012 Springer Science+Business Media New York
Heuristic Models of Two-Fermion Relativistic Systems with Field-Type Interaction
We use the chain of simple heuristic expedients to obtain perturbative and
exactly solvable relativistic spectra for a family of two-fermionic bound
systems with Coulomb-like interaction. In the case of electromagnetic
interaction the spectrum coincides up to the second order in a coupling
constant with that following from the quantum electrodynamics. Discrepancy
occurs only for S-states which is the well-known difficulty in the bound-state
problem. The confinement interaction is considered too.
PACS number(s): 03.65.Pm, 03.65.Ge, 12.39.PnComment: 16 pages, LaTeX 2.0
Arylselenovinyl sulfones: II. Addition of benzeneselenols to aryl ethynyl sulfones
Depending on the solvent nature, addition of benzeneselenols to aryl ethynyl sulfones leads to formation of a mixture of (E)- and (Z)-1-arylseleno-2-arylsulfonylethenes and 1-arylseleno-1-arylsulfonylethenes (in carbon tetrachloride and cyclohexane) or (Z)-1-arylseleno-2- arylsulfonylethenes as a single product (in alcohols)
Classical Cepheids and the spiral structure of the Milky Way
We use the currently most complete collection of reliable Cepheid positions
(565 stars) out to ~5 kpc based mostly on our photometric data to outline the
spiral pattern of our Galaxy. We find the pitch-angle to be equal to 9--10
degrees with the most accurate estimate (i=9.5 +/-0.1 degrees) obtained
assuming that the spiral pattern has a four-armed structure, and the solar
phase angle in the spiral pattern to be chi_0 = 121+/-3 degrees. The pattern
speed is found to be Omega_P=25.2+/-0.5km/s/kpc based on a comparison of the
positions of the spiral arms delineated by Cepheids and maser sources and the
age difference between these objects.Comment: 21 pages, 11 figures. To appear in Astronomy Letter
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