16,838 research outputs found
Unifying the Fixed Order Evolution of Fragmentation Functions with the Modified Leading Logarithm Approximation
An approach which unifies the Double Logarithmic Approximation at small x and
the leading order DGLAP evolution of fragmentation functions at large x is
presented. This approach reproduces exactly the Modified Leading Logarithm
Approximation, but is more complete due to the degrees of freedom given to the
quark sector and the inclusion of the fixed order terms. We find that data from
the largest x values to the peak region can be better fitted than with other
approaches
Anderson transitions in three-dimensional disordered systems with randomly varying magnetic flux
The Anderson transition in three dimensions in a randomly varying magnetic
flux is investigated in detail by means of the transfer matrix method with high
accuracy. Both, systems with and without an additional random scalar potential
are considered. We find a critical exponent of with random
scalar potential. Without it, is smaller but increases with the system
size and extrapolates within the error bars to a value close to the above. The
present results support the conventional classification of universality classes
due to symmetry.Comment: 4 pages, 2 figures, to appear in Phys. Rev.
Observables in the Decays of B to Two Vector Mesons
In general there are nine observables in the decay of a B meson to two vector
mesons defined in terms of polarization correlations of these mesons. Only six
of these can be detected via the subsequent decay angular distributions because
of parity conservation in those decays. The remaining three require the
measurement of the spin polarization of one of the decay products.Comment: 12 pages, no figur
Detection of the gravitomagnetic clock effect
The essence of the gravitomagnetic clock effect is properly defined showing
that its origin is in the topology of world lines with closed space
projections. It is shown that, in weak field approximation and for a
spherically symmetric central body, the loss of synchrony between two clocks
counter-rotating along a circular geodesic is proportional to the angular
momentum of the source of the gravitational field. Numerical estimates are
presented for objects within the solar system. The less unfavorable situation
is found around Jupiter.Comment: 14 pages; Latex. To be published on Classical and Quantum Gravit
Long-term Observations of Three Nulling Pulsars
We present an analysis of approximately 200 hours of observations of the
pulsars J16345107, J17174054 and J18530505, taken over the course of
14.7 yr. We show that all of these objects exhibit long term nulls and
radio-emitting phases (i.e. minutes to many hours), as well as considerable
nulling fractions (NFs) in the range . PSR J17174054 is
also found to exhibit short timescale nulls () and burst phases
() during its radio-emitting phases. This behaviour acts to
modulate the NF, and therefore the detection rate of the source, over
timescales of minutes. Furthermore, PSR J18530505 is shown to exhibit a weak
emission state, in addition to its strong and null states, after sufficient
pulse integration. This further indicates that nulls may often only represent
transitions to weaker emission states which are below the sensitivity
thresholds of particular observing systems. In addition, we detected a
peak-to-peak variation of in the spin-down rate of PSR
J17174054, over timescales of hundreds of days. However, no long-term
correlation with emission variation was found.Comment: 10 pages, 8 figures, accepted for publication in MNRA
Apollo-11 lunar sample information catalogue
The Apollo 11 mission is reviewed with emphasis on the collection of lunar samples, their geologic setting, early processing, and preliminary examination. The experience gained during five subsequent missions was applied to obtain physical-chemical data for each sample using photographic and binocular microscope techniques. Topics discussed include: binocular examination procedure; breccia clast dexrriptuons, thin section examinations procedure typical breccia in thin section, typical basalt in thin section, sample histories, and chemical and age data. An index to photographs is included
Hysteresis in the de Haas-van Alphen Effect
A hysteresis loop is observed for the first time in the de Haas-van Alphen
(dHvA) effect of beryllium at low temperatures and quantizing magnetic field
applied parallel to the hexagonal axis of the single crystal. The irreversible
behavior of the magnetization occurs at the paramagnetic part of the dHvA
period in conditions of Condon domain formation arising by strong enough dHvA
amplitude. The resulting extremely nonlinear response to a very small
modulation field offers the possibility to find in a simple way the Condon
domain phase diagram. From a harmonic analysis, the shape and size of the
hysteresis loop is constructed.Comment: 4 pages, 5 figures, submitted to PR
Neutron Stars as Type-I Superconductors
In a recent paper by Link, it was pointed out that the standard picture of
the neutron star core composed of a mixture of a neutron superfluid and a
proton type-II superconductor is inconsistent with observations of a long
period precession in isolated pulsars. In the following we will show that an
appropriate treatment of the interacting two-component superfluid (made of
neutron and proton Cooper pairs), when the structure of proton vortices is
strongly modified, may dramatically change the standard picture, resulting in a
type-I superconductor. In this case the magnetic field is expelled from the
superconducting regions of the neutron star leading to the formation of the
intermediate state when alternating domains of superconducting matter and
normal matter coexist.Comment: 4 page
Be Patient When Measuring Hyperbolic Discounting: Stationarity, Time Consistency and Time Invariance in a Field Experiment
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