3,844 research outputs found
A Monte Carlo Test of the Optimal Jet Definition
We summarize the Optimal Jet Definition and present the result of a benchmark
Monte Carlo test based on the W-boson mass extraction from fully hadronic
decays of pairs of W's.Comment: 7 pages, talk given at Lake Louise Winter Institute: "Particles and
the Universe", Lake Louise, Canada, February 16-22, 2003, to be published in
the proceeding
Electron mobility on a surface of dielectric media: influence of surface level atoms
We calculate the contribution to the electron scattering rate from the
surface level atoms (SLA), proposed in [A.M. Dyugaev, P.D. Grigoriev, JETP
Lett. 78, 466 (2003)]. The inclusion of these states into account was
sufficient to explain the long-standing puzzles in the temperature dependence
of the surface tension of both He isotopes and to reach a very good agreement
between theory and experiment. We calculate the contribution from these SLA to
the surface electron scattering rate and explain some features in the
temperature dependence of the surface electron mobility. This contribution is
essential at low temperature when the He vapor concentration is
exponentially small. For an accurate calculation of the electron mobility one
also needs to consider the influence of the clamping electric field on the
surface electron wave function and the temperature dependence of the He3
chemical potential.Comment: 6 pages, 1 figur
Controlling Physical Systems with Symmetries
Symmetry properties of the evolution equation and the state to be controlled
are shown to determine the basic features of the linear control of unstable
orbits. In particular, the selection of control parameters and their minimal
number are determined by the irreducible representations of the symmetry group
of the linearization about the orbit to be controlled. We use the general
results to demonstrate the effect of symmetry on the control of two sample
physical systems: a coupled map lattice and a particle in a symmetric
potential.Comment: 6 page
Complex Chiral Modulations in FeGe close to Magnetic Ordering
We report on detailed polarized small-angle neutron scattering on cubic FeGe
in magnetic fields applied either along (transverse) the scattering vector or
parallel (longitudinal)to the neutron beam. The () phase diagrams for all
principal axes contain a segmented -phase region just below the onset of
magnetic order. Hexagonal Bragg-spot patterns were observed across the entire
-phase region for the longitudinal geometry. Scattering intensity was
observed in parts of the A phase for both scattering configurations. Only in a
distinct pocket () vanishing scattering intensity was found in the
transverse geometry.Comment: This paper has been withdrawn by the author due to misunderstanding
with some of the co-author
Slow oscillations of magnetoresistance in quasi-two-dimensional metals
Slow oscillations of the interlayer magnetoresistance observed in the layered
organic metal -(BEDT-TTF)IBr are shown to originate from the
slight warping of its Fermi surface rather than from independent small
cyclotron orbits. Unlike the usual Shubnikov-de Haas effect, these oscillations
are not affected by the temperature smearing of the Fermi distribution and can
therefore become dominant at high enough temperatures. We suggest that the slow
oscillations are a general feature of clean quasi-two-dimensional metals and
discuss possible applications of the phenomenon.Comment: 11 pages, 3 figure
Chiral criticality in doped MnFeSi compounds
The critical spin fluctuations in doped compounds MnFeSi have
been studied by means of ac-susceptibility measurements, polarized neutron
small angle scattering and spin echo spectroscopy. It is shown that these
compounds undergo the transition from the paramagnetic to helimagnetic phase
through continuous, yet well distinguishable crossovers: (i) from paramagnetic
to partially chiral, (ii) from partially chiral to highly chiral fluctuating
state. The crossover points are identified on the basis of combined analysis of
the temperature dependence of ac-susceptibility and polarized SANS data. The
whole transition is marked by two inflection point of the temperature
dependence of ac-susceptibility: the upper one corresponds to the crossover to
partially chiral state at , where the inverse correlation length , the lower one corresponds to the transition to the spin helix
structure. The intermediate crossover to the highly chiral phase is observed at
the inflection point of the first derivative of ac-susceptibility, where
. The temperature crossovers to the highly chiral fluctuating
state is associated with the enhancing influence of the Dzyaloshinskii-Moria
interaction close to .Comment: 5 pages, 5 figures, 1 table, 13 cite
Neutrino spin evolution in presence of general external fields
The derivation of the quasiclassical Lorentz invariant neutrino spin
evolution equation taking into account general types of neutrino non-derivative
interactions with external fields is presented. We discuss the constraints on
the characteristics of matter and neutrino under which this quasiclassical
approach is valid. The application of the obtained equation for the case of the
Standard Model neutrino interactions with moving and polarized background
matter is considered.Comment: The form of the article has been sufficiently improve
An algorithm for calculating the Lorentz angle in silicon detectors
Future experiments will use silicon sensors in the harsh radiation
environment of the LHC (Large Hadron Collider) and high magnetic fields. The
drift direction of the charge carriers is affected by the Lorentz force due to
the high magnetic field. Also the resulting radiation damage changes the
properties of the drift.
In this paper measurements of the Lorentz angle of electrons and holes before
and after irradiation are reviewed and compared with a simple algorithm to
compute the Lorentz angle.Comment: 13 pages, 7 figures, final version accepted by NIMA. Mainly
clarifications included and slightly shortene
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