39,234 research outputs found
A theory of hyperfinite sets
We develop an axiomatic set theory -- the Theory of Hyperfinite Sets THS,
which is based on the idea of existence of proper subclasses of big finite
sets. We demonstrate how theorems of classical continuous mathematics can be
transfered to THS, prove consistency of THS and present some applications.Comment: 28 page
Acceleration Of Protons To Above 6 MeV Using H2O >Snow> Nanowire Targets
A scheme is presented for using H2O >snow> nanowire targets for the generation of fast protons. This novel method may relax the requirements for very high laser intensities, thus reducing the size and cost of laser based ion acceleration system.Physic
Critical Behavior of Light
Light is shown to exhibit critical and tricritical behavior in passive
mode-locked lasers with externally injected pulses. It is a first and unique
example of critical phenomena in a one-dimensional many body light-mode system.
The phase diagrams consist of regimes with continuous wave, driven para-pulses,
spontaneous pulses via mode condensation, and heterogeneous pulses, separated
by phase transition lines which terminate with critical or tricritical points.
Enhanced nongaussian fluctuations and collective dynamics are observed at the
critical and tricritical points, showing a mode system analog of the critical
opalescence phenomenon. The critical exponents are calculated and shown to
comply with the mean field theory, which is rigorous in the light system.Comment: RevTex, 5 pages, 3 figure
Prompt Photon Plus Jet Photoproduction at HERA at Next-to-Leading Order in QCD
The cross section for photoproduction of an isolated prompt photon in
association with a jet is studied in Next-to-Leading Order. The kinematics are
those appropriate for the DESY collider HERA. The effects on the cross
section of various experimental cuts including isolation cuts on the photon is
examined. Comparisons with the ZEUS preliminary data using two parametrizations
of the photon structure function is made, and good agreement is found. The data
is not yet precise enough to make a distinction between various models for the
photon structure function.Comment: Uses eps
Spin Dependence of Massive Lepton Pair Production in Proton-Proton Collisions
We calculate the transverse momentum distribution for the production of
massive lepton-pairs in longitudinally polarized proton-proton reactions at
collider energies within the context of perturbative quantum chromodynamics.
For values of the transverse momentum Q_T greater than roughly half the pair
mass Q, Q_T > Q/2, we show that the differential cross section is dominated by
subprocesses initiated by incident gluons, provided that the polarized gluon
density is not too small. Massive lepton-pair differential cross sections
should be a good source of independent constraints on the polarized gluon
density, free from the experimental and theoretical complications of photon
isolation that beset studies of prompt photon production. We provide
predictions for the spin-averaged and spin-dependent differential cross
sections as a function of Q_T at energies relevant for the Relativistic Heavy
Ion Collider (RHIC) at Brookhaven, and we compare these with predictions for
real prompt photon production.Comment: 34 pages, RevTeX including 17 figures in .ps file
Massive Lepton Pairs as a Prompt Photon Surrogate
We discuss the transverse momentum distribution for the production of massive
lepton-pairs in hadron reactions at fixed target and collider energies within
the context of next-to-leading order perturbative quantum chromodynamics. For
values of the transverse momentum greater than the pair mass , , we show that the differential cross section is dominated by subprocesses
initiated by incident gluons. Massive lepton-pair differential cross sections
are an advantageous source of constraints on the gluon density, free from the
experimental and theoretical complications of photon isolation that beset
studies of prompt photon production. We compare calculations with data and
provide predictions for the differential cross section as a function of
in proton-antiproton reactions at center-of-mass energies of 1.8 TeV, and in
proton-nucleon reactions at fixed target and LHC energies.Comment: 36 pages, RevTeX, including 16 ps files of figures; minor changes in
wording; one reference added. Version to appear in Phys Rev
The classical capacity of quantum thermal noise channels to within 1.45 bits
We find a tight upper bound for the classical capacity of quantum thermal
noise channels that is within bits of Holevo's lower bound. This
lower bound is achievable using unentangled, classical signal states, namely
displaced coherent states. Thus, we find that while quantum tricks might offer
benefits, when it comes to classical communication they can only help a bit.Comment: Two pages plus a bi
On charged impurity structures in liquid helium
The thermoluminescence spectra of impurity-helium condensates (IHC) submerged in superfluid helium have
been observed for the first time. Thermoluminescence of impurity-helium condensates submerged in superfluid
helium is explained by neutralization reactions occurring in impurity nanoclusters. Optical spectra of excited
products of neutralization reactions between nitrogen cations and thermoactivated electrons were rather different
from the spectra observed at higher temperatures, when the luminescence due to nitrogen atom recombination
dominates. New results on current detection during the IHC destruction are presented. Two different mechanisms
of nanocluster charging are proposed to describe the phenomena observed during preparation and warmup
of IHC samples in bulk superfluid helium, and destruction of IHC samples out of liquid helium
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