9,431 research outputs found
Diffusion in simple fluids
Computed self diffusion coefficients for the Lennard-Jones and hard sphere fluids are related by
Dej = DNs(aB) exp (--e/2kB T)
where σB=σLJ(2/[1+ii(1+2kBT/ε)])1/6, the effective hard sphere diameter, is the (average) distance of closest approach in collisions between molecules which interact with the positive part of the LJ potential, and the Arrhenius term reflects the influence of the negative part. σLJ and ε are the size and well depth parameters. Measured diffusion coefficients of the halomethane liquids are reproduced by the equation over wide ranges of temperature and density and do not reveal any influence of the inelastic effects associated with molecular anisotropy
Variational energies and the Fermi contact term for the low-lying states of lithium: Basis-set completeness
Nonrelativistic energies for the low-lying states of lithium are calculated using the variational method in Hylleraas coordinates. Variational eigenvalues for the infinite nuclear mass case with up to 34020 terms are -7.478060323910147(1) a.u. for 1s22s2S, -7.35409842144437(1) a.u. for 1s23s2S, -7.31853084599891(1) a.u. for 1s24s2S, -7.41015653265241(4) a.u. for 1s22p2P, and -7.335523543524688(3) a.u. for 1s23d2D. The selection of the minimum set of angular momentum configurations is discussed, with the 2P and 3D states as examples to demonstrate the impact of various configurations on the variational energies. It is shown by numerical example that the second spin function (i.e., coupled to form a triplet intermediate state) has no significant effect on either the variational energies or the spin-dependent Fermi contact term. Results of greatly improved accuracy for the Fermi contact term are presented for all the states considered. © 2012 American Physical Society
Disorder Effect on the Vortex Pinning by the Cooling Process Control in the Organic Superconductor -(BEDT-TTF)Cu[N(CN)]Br
We investigate the influence of disorders in terminal ethylene groups of
BEDT-TTF molecules (ethylene-disorders) on the vortex pinning of the organic
superconductor -(BEDT-TTF)Cu[N(CN)]Br. Magnetization
measurements are performed under different cooling-processes. The second peak
in the magnetization hysteresis curve is observed for all samples studied, and
the hysteresis width of the magnetization becomes narrower by cooling faster.
In contradiction to the simple pinning effect of disorder, this result shows
the suppression of the vortex pinning force by introducing more
ethylene-disorders. The ethylene-disorder domain model is proposed for
explaining the observed result. In the case of the system containing a moderate
number of the ethylene-disorders, the disordered molecules form a domain
structure and it works as an effective pinning site. On the contrary, an excess
number of the ethylene-disorders may weaken the effect of the domain structure,
which results in the less effective pinning force on the vortices.Comment: 6 pages, 6 figure
Geometric measure of quantum discord and the geometry of a class of two-qubit states
We investigate the geometric picture of the level surfaces of quantum
entanglement and geometric measure of quantum discord (GMQD) of a class of
X-states, respectively. This pictorial approach provides us a direct
understanding of the structure of entanglement and GMQD. The dynamic evolution
of GMQD under two typical kinds of quantum decoherence channels is also
investigated. It is shown that there exists a class of initial states for which
the GMQD is not destroyed by decoherence in a finite time interval.
Furthermore, we establish a factorization law between the initial and final
GMQD, which allows us to infer the evolution of entanglement under the
influences of the environment.Comment: 10 pages, 4 figures, comments are welcom
Mining State-Based Models from Proof Corpora
Interactive theorem provers have been used extensively to reason about
various software/hardware systems and mathematical theorems. The key challenge
when using an interactive prover is finding a suitable sequence of proof steps
that will lead to a successful proof requires a significant amount of human
intervention. This paper presents an automated technique that takes as input
examples of successful proofs and infers an Extended Finite State Machine as
output. This can in turn be used to generate proofs of new conjectures. Our
preliminary experiments show that the inferred models are generally accurate
(contain few false-positive sequences) and that representing existing proofs in
such a way can be very useful when guiding new ones.Comment: To Appear at Conferences on Intelligent Computer Mathematics 201
Effects of the R-parity violation in the minimal supersymmetric standard model on dilepton pair production at the CERN LHC
We investigate in detail the effects of the R-parity lepton number violation
in the minimal supersymmetric standard model (MSSM) on the parent process at the CERN Large Hadron Collider (LHC). The numerical
comparisons between the contributions of the R-parity violating effects to the
parent process via the Drell-Yan subprocess and the gluon-gluon fusion are
made. We find that the R-violating effects on pair production at the
LHC could be significant. The results show that the cross section of the pair productions via gluon-gluon collision at the LHC can be of the order
of fb, and this subprocess maybe competitive with the production
mechanism via the Drell-Yan subprocess. We give also quantitatively the
analysis of the effects from both the mass of sneutrino and coupling strength
of the R-parity violating interactions.Comment: 18 pages, 10 figures, accepted by Phys. Rev.
The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: selecting emission line galaxies using the Fisher discriminant
We present a new selection technique of producing spectroscopic target
catalogues for massive spectroscopic surveys for cosmology. This work was
conducted in the context of the extended Baryon Oscillation Spectroscopic
Survey (eBOSS), which will use ~200 000 emission line galaxies (ELGs) at
0.6<zspec<1.0 to obtain a precise baryon acoustic oscillation measurement. Our
proposed selection technique is based on optical and near-infrared broad-band
filter photometry. We used a training sample to define a quantity, the Fisher
discriminant (linear combination of colours), which correlates best with the
desired properties of the target: redshift and [OII] flux. The proposed
selections are simply done by applying a cut on magnitudes and this Fisher
discriminant. We used public data and dedicated SDSS spectroscopy to quantify
the redshift distribution and [OII] flux of our ELG target selections. We
demonstrate that two of our selections fulfil the initial eBOSS/ELG redshift
requirements: for a target density of 180 deg^2, ~70% of the selected objects
have 0.6<zspec<1.0 and only ~1% of those galaxies in the range 0.6<zspec<1.0
are expected to have a catastrophic zspec estimate. Additionally, the stacked
spectra and stacked deep images for those two selections show characteristic
features of star-forming galaxies. The proposed approach using the Fisher
discriminant could, however, be used to efficiently select other galaxy
populations, based on multi-band photometry, providing that spectroscopic
information is available. This technique could thus be useful for other future
massive spectroscopic surveys such as PFS, DESI, and 4MOST.Comment: Version published in A&
Measurement of decays to baryon pairs
A sample of 3.95M decays registered in the BES detector are used
to study final states containing pairs of octet and decuplet baryons. We report
branching fractions for , ,
, ,
, ,
, and . These results
are compared to expectations based on the SU(3)-flavor symmetry, factorization,
and perturbative QCD.Comment: 22 pages, 21 figures, 4 table
Impurity Effect on the In-plane Penetration Depth of the Organic Superconductors -(BEDT-TTF) ( = Cu(NCS) and Cu[N(CN)]Br)
We report the in-plane penetration depth of single
crystals -(BEDT-TTF) ( Cu(NCS) and Cu[N(CN)]Br) by
means of the reversible magnetization measurements under the control of
cooling-rate. In = Cu(NCS), as an
extrapolation toward = 0 K does not change by the cooling-rate within the
experimental accuracy, while is slightly reduced. On the other
hand, in = Cu[N(CN)]Br, indicates a distinct
increase by cooling faster. The different behavior of
on cooling-rate between the two salts is quantitatively explained in terms of
the local-clean approximation (London model), considering that the former salt
belongs to the very clean system and the later the moderate clean one. The good
agreement with this model demonstrates that disorders of ethylene-group in
BEDT-TTF introduced by cooling faster increase the
electron(quasiparticle)-scattering, resulting in shorter mean free path.Comment: 8 pages, 9 figure
Learning Moore Machines from Input-Output Traces
The problem of learning automata from example traces (but no equivalence or
membership queries) is fundamental in automata learning theory and practice. In
this paper we study this problem for finite state machines with inputs and
outputs, and in particular for Moore machines. We develop three algorithms for
solving this problem: (1) the PTAP algorithm, which transforms a set of
input-output traces into an incomplete Moore machine and then completes the
machine with self-loops; (2) the PRPNI algorithm, which uses the well-known
RPNI algorithm for automata learning to learn a product of automata encoding a
Moore machine; and (3) the MooreMI algorithm, which directly learns a Moore
machine using PTAP extended with state merging. We prove that MooreMI has the
fundamental identification in the limit property. We also compare the
algorithms experimentally in terms of the size of the learned machine and
several notions of accuracy, introduced in this paper. Finally, we compare with
OSTIA, an algorithm that learns a more general class of transducers, and find
that OSTIA generally does not learn a Moore machine, even when fed with a
characteristic sample
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