9,466 research outputs found
Resolvent convergence of Sturm-Liouville operators with singular potentials
In this paper we consider the Sturm-Liuoville operator in the Hilbert space
with the singular complex potential of and two-point boundary
conditions. For this operator we give sufficient conditions for norm resolvent
approximation by the operators of the same class.Comment: 6 pages, to appear in Math. Note
QND and higher order effects for a nonlinear meter in an interferometric gravitational wave antenna
A new optical topology and signal readout strategy for a laser interferometer
gravitational wave detector were proposed recently by Braginsky and Khalili .
Their method is based on using a nonlinear medium inside a microwave oscillator
to detect the gravitational-wave-induced spatial shift of the interferometer's
standing optical wave. This paper proposes a quantum nondemolition (QND) scheme
that could be realistically used for such a readout device and discusses a
"fundamental" sensitivity limit imposed by a higher order optical effect.Comment: LaTex, 17 pages, 3 figure
Quark structure of hadrons and high energy collisions
There exists a large field for phenomenological models in which the knowledge
of the structure of hadrons in terms of QCD constituents obtained from deep
inelastic scatterings is related to their behaviour in soft processes. One of
the simplest and oldest models is the additive quark model, with the rules of
quark statistics following from it. Originally, the relations of quark
combinatorics for hadron yields were based on the qualitative description of a
multiparticle production process as a process of the production of
non-correlated quarks and antiquarks followed by their subsequent fusion into
hadrons [20],[21]. As a large amount of new precision measurements appear, and,
on the other hand, our understanding of QCD becomes deeper, a new level of
understanding of quark-gluon physics in the region of soft interactions forces
us to review the relations of quark combinatorics. To do so, an especially good
possibility is provided by the experimental data for hadronic Z^0 decays which
allow us to check the relations of quark combinatorics for a new type of
processes: quark jets in the decays Z^0 -> q\bar{q} -> hadrons [32].Comment: 55 pages, 23 figure
How to reduce the suspension thermal noise in LIGO without improving the Q's of the pendulum and violin modes
The suspension noise in interferometric gravitational wave detectors is
caused by losses at the top and the bottom attachments of each suspension
fiber. We use the Fluctuation-Dissipation theorem to argue that by careful
positioning of the laser beam spot on the mirror face it is possible to reduce
the contribution of the bottom attachment point to the suspension noise by
several orders of magnitude. For example, for the initial and enhanced LIGO
design parameters (i.e. mirror masses and sizes, and suspension fibers' lengths
and diameters) we predict a reduction of in the "bottom" spectral
density throughout the band of serious thermal noise. We then
propose a readout scheme which suppresses the suspension noise contribution of
the top attachment point. The idea is to monitor an averaged horizontal
displacement of the fiber of length ; this allows one to record the
contribution of the top attachment point to the suspension noise, and later
subtract it it from the interferometer readout. For enhanced LIGO this would
allow a suppression factor about 100 in spectral density of suspension thermal
noise.Comment: a few misprints corrected; submitted to Classical and Quantum Gravit
Speed Meter As a Quantum Nondemolition Measuring Device for Force
Quantum noise is an important issue for advanced LIGO. Although it is in
principle possible to beat the Standard Quantum Limit (SQL), no practical
recipe has been found yet. This paper dicusses quantum noise in the context of
speedmeter-a devise monitoring the speed of the testmass. The scheme proposed
to overcome SQL in this case might be more practical than the methods based on
monitoring position of the testmass.Comment: 7 pages of RevTex, 1 postscript figur
Thermoelastic Noise and Homogeneous Thermal Noise in Finite Sized Gravitational-Wave Test Masses
An analysis is given of thermoelastic noise (thermal noise due to
thermoelastic dissipation) in finite sized test masses of laser interferometer
gravitational-wave detectors. Finite-size effects increase the thermoelastic
noise by a modest amount; for example, for the sapphire test masses tentatively
planned for LIGO-II and plausible beam-spot radii, the increase is less than or
of order 10 per cent. As a side issue, errors are pointed out in the currently
used formulas for conventional, homogeneous thermal noise (noise associated
with dissipation which is homogeneous and described by an imaginary part of the
Young's modulus) in finite sized test masses. Correction of these errors
increases the homogeneous thermal noise by less than or of order 5 per cent for
LIGO-II-type configurations.Comment: 10 pages and 3 figures; RevTeX; submitted to Physical Review
Polaron and bipolaron transport in a charge segregated state of doped strongly correlated 2D semiconductor
The 2D lattice gas model with competing short and long range interactions is
appliedused for calculation of the incoherent charge transport in the classical
strongly-correlated charge segregated polaronic state. We show, by means of
Monte-Carlo simulations, that at high temperature the transport is dominated by
hopping of the dissociated correlated polarons, where with thetheir mobility is
inversely proportional to the temperature. At the temperatures below the
clustering transition temperature the bipolaron transport becomes dominant. The
energy barrier for the bipolaron hopping is determined by the Coulomb effects
and is found to be lower than the barrier for the single-polaron hopping. This
leads to drastically different temperature dependencies of mobilities for
polarons and bipolarons at low temperatures
- …