19,748 research outputs found
A Binary Shaped Mask Coronagraph for a Segmented Pupil
We present the concept of a binary shaped mask coronagraph applicable to a
telescope pupil including obscuration, based on previous works on binary shaped
pupil mask by \citet{Kasdin2005} and \citet{Vanderbei1999}. Solutions with
multi-barcode masks which "skip over" the obscuration are shown for various
types of pupil of telescope, such as SUBARU, JWST, SPICA, and other examples.
The number of diffraction tails in the point spread function of the
coronagraphic image is reduced to two, thus offering a large discovery angle.
The concept of mask rotation is also presented, which allows post-processing
removal of diffraction tails and provides a 360 continuous discovery
angle. It is suggested that the presented concept offers solutions which
potentially allow large telescopes with segmented pupil in future to be used as
platforms for an coronagraph.Comment: 12 pages, 4 figure
Geometry of escort distributions
Given an original distribution, its statistical and probabilistic attributs
may be scanned by the associated escort distribution introduced by Beck and
Schlogl and employed in the formulation of nonextensive statistical mechanics.
Here, the geometric structure of the one-parameter family of the escort
distributions is studied based on the Kullback-Leibler divergence and the
relevant Fisher metric. It is shown that the Fisher metric is given in terms of
the generalized bit-variance, which measures fluctuations of the crowding index
of a multifractal. The Cramer-Rao inequality leads to the fundamental limit for
precision of statistical estimate of the order of the escort distribution. It
is also quantitatively discussed how inappropriate it is to use the original
distribution instead of the escort distribution for calculating the expectation
values of physical quantities in nonextensive statistical mechanics.Comment: 12 pages, no figure
Universal law for waiting internal time in seismicity and its implication to earthquake network
In their paper (Europhys. Lett., 71 (2005) 1036), Carbone, Sorriso-Valvo,
Harabaglia and Guerra showed that "unified scaling law" for conventional
waiting times of earthquakes claimed by Bak et al. (Phys. Rev. Lett., 88 (2002)
178501) is actually not universal. Here, instead of the conventional time, the
concept of the internal time termed the event time is considered for
seismicity. It is shown that, in contrast to the conventional waiting time, the
waiting event time obeys a power law. This implies the existence of temporal
long-range correlations in terms of the event time with no sharp decay of the
crossover type. The discovered power-law waiting event-time distribution turns
out to be universal in the sense that it takes the same form for seismicities
in California, Japan and Iran. In particular, the parameters contained in the
distribution take the common values in all these geographical regions. An
implication of this result to the procedure of constructing earthquake networks
is discussed.Comment: 21 pages, 5 figure
Heavy-quark jets in hadronic collisions
We present a next-to-leading order QCD calculation of the production rates of
jets containing heavy quarks. This calculation is performed using the standard
Snowmass jet algorithm; it therefore allows a comparison with similar results
known at next-to-leading order for generic jets. As an application, we present
results for the inclusive transverse energy of charm and bottom jets at the
Tevatron collider, with a complete study of the dependence on the jet cone-size
and of the theoretical uncertainties.Comment: 23 pages Latex, uses epsfig.sty, 16 eps figures appended as
uuencoded, gzipped, tarred fil
Aftershocks in Modern Perspectives: Complex Earthquake Network, Aging, and Non-Markovianity
The phenomenon of aftershocks is studied in view of science of complexity. In
particular, three different concepts are examined: (i) the complex-network
representation of seismicity, (ii) the event-event correlations, and (iii) the
effects of long-range memory. Regarding (i), it is shown the clustering
coefficient of the complex earthquake network exhibits a peculiar behavior at
and after main shocks. Regarding (ii), it is found that aftershocks experience
aging, and the associated scaling holds. And regarding (iii), the scaling
relation to be satisfied by a class of singular Markovian processes is
violated, implying the existence of the long-range memory in processes of
aftershocks.Comment: 28 pages, 6 figures and 1 table. Acta Geophysica, in pres
Light Bottom Squark Phenomenology
Agreement of theoretical calculations with the observed production rate of
bottom quarks at hadron colliders is improved by the introduction of a
contribution from pair-production of light gluinos, of mass 12 to 16 GeV,
having two-body decays into bottom quarks and light bottom squarks with mass
to 5.5 GeV. Predictions are made for hadronic and radiative decays
of the Upsilon states. In the limit of large , the dominant decay
mode of the light scalar Higgs boson is into a pair of light bottom squarks
that materialize as jets of hadrons.Comment: 3 pages, latex, no figures, uses espcrc2.sty style file. Paper to be
published in the Proceedings of the 31st International Conference on High
Energy Physics (ICHEP02), Amsterdam, July 24 - 31, 200
Macroscopic proof of the Jarzynski-Wojcik fluctuation theorem for heat exchange
In a recent work, Jarzynski and Wojcik (2004 Phys. Rev. Lett. 92, 230602)
have shown by using the properties of Hamiltonian dynamics and a statistical
mechanical consideration that, through contact, heat exchange between two
systems initially prepared at different temperatures obeys a fluctuation
theorem. Here, another proof is presented, in which only macroscopic
thermodynamic quantities are employed. The detailed balance condition is found
to play an essential role. As a result, the theorem is found to hold under very
general conditions.Comment: 9 pages, 0 figure
About the modern "experimental value" of W boson width.
It is shown that the methods which have been used up to now to determine the
width from the data confirm the SM predictions for some
combinations of various phenomenological parameters, however, they do not give
an independent value for the width. Moreover, the accuracy that could be
achieved in future experimental checks of SM predictions for such quantities is
limited by effects which require detailed theoretical study.Comment: Latex, 8 pages
Slow positron beam generator for lifetime studies
A slow positron beam generator uses a conductive source residing between two test films. Moderator pieces are placed next to the test film on the opposite side of the conductive source. A voltage potential is applied between the moderator pieces and the conductive source. Incident energetic positrons: (1) are emitted from the conductive source; (2) are passed through test film; and (3) isotropically strike moderator pieces before diffusing out of the moderator pieces as slow positrons, respectively. The slow positrons diffusing out of moderator pieces are attracted to the conductive source which is held at an appropriate potential below the moderator pieces. The slow positrons have to pass through the test films before reaching the conductive source. A voltage is adjusted so that the potential difference between the moderator pieces and the conductive source forces the positrons to stop in the test films. Measurable annihilation radiation is emitted from the test film when positrons annihilate (combine) with electrons in the test film
Validity of the second law in nonextensive quantum thermodynamics
The second law of thermodynamics in nonextensive statistical mechanics is
discussed in the quantum regime. Making use of the convexity property of the
generalized relative entropy associated with the Tsallis entropy indexed by q,
Clausius' inequality is shown to hold in the range of q between zero and two.
This restriction on the range of the entropic index, q, is purely quantum
mechanical and there exists no upper bound of q for validity of the second law
in classical theory.Comment: 12 pages, no figure
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