34,636 research outputs found
QCD Factorization for Semi-Inclusive Deep-Inelastic Scattering at Low Transverse Momentum
We demonstrate a factorization formula for semi-inclusive deep-inelastic
scattering with hadrons in the current fragmentation region detected at low
transverse momentum. To facilitate the factorization, we introduce the
transverse-momentum dependent parton distributions and fragmentation functions
with gauge links slightly off the light-cone, and with soft-gluon radiations
subtracted. We verify the factorization to one-loop order in perturbative
quantum chromodynamics and argue that it is valid to all orders in perturbation
theory.Comment: 28 pages, figures include
Opacification of high temperature fibrous insulation
A study was conducted to determine the merits of adding particulate materials to silica fiber felts to increase their resistance to the passage of thermal radiation. Laboratory samples containing 5, 10, and 15 percent of chromium oxide, silicon carbide, and titanium dioxide were prepared and evaluated in accordance with ASTM C-518 thermal conductivity test method at 425 C (800 F) mean temperature. The titania particles averaging 3-4 micrometers in diameter were found to be the most effective. This was followed by a short plant run, in order to confirm the initial results on the laboratory samples. These samples were tested according to ASTM C-201 High Temperature Calorimeter from 93 C to 760 C (200 F to 1400 F) mean temperature. The ten percent by weight of titania resulted in an optimum effectiveness, and reduced the conductivity over 20% at 760 C (1400 F)
X-ray photoelectron spectroscopy investigation of the mixed anion GaSb/InAs heterointerface
X-ray photoelectron spectroscopy has been used to measure levels of anion cross-incorporation and to study interface formation for the mixed anion GaSb/lnAs heterojunction. Anion
cross-incorporation was measured in 20 Ã… thick GaSb layers grown on lnAs, and 20 Ã… thick InAs layers grown on GaSb for cracked and uncracked sources. It was found that significantly
less anion cross-incorporation occurs in structures grown with cracked sources. Interface formation was investigated by studying Sb soaks of InAs surfaces and As soaks of GaSb surfaces
as a function of cracker power and soak time. Exchange of the group V surface atoms was found to be an increasing function of both cracker power and soak time. We find that further
optimization of current growth parameters may be possible by modifying the soak time used at interfaces
Mixed state Pauli channel parameter estimation
The accuracy of any physical scheme used to estimate the parameter describing
the strength of a single qubit Pauli channel can be quantified using standard
techniques from quantum estimation theory. It is known that the optimal
estimation scheme, with m channel invocations, uses initial states for the
systems which are pure and unentangled and provides an uncertainty of
O[1/m^(1/2)]. This protocol is analogous to a classical repetition and
averaging scheme. We consider estimation schemes where the initial states
available are not pure and compare a protocol involving quantum correlated
states to independent state protocols analogous to classical repetition
schemes. We show, that unlike the pure state case, the quantum correlated state
protocol can yield greater estimation accuracy than any independent state
protocol. We show that these gains persist even when the system states are
separable and, in some cases, when quantum discord is absent after channel
invocation. We describe the relevance of these protocols to nuclear magnetic
resonance measurements
Next-to-leading order QCD corrections to single-inclusive hadron production in transversely polarized p-p and pbar-p collisions
We present a calculation of the next-to-leading order QCD corrections to the
partonic cross sections contributing to single-inclusive high-p_T hadron
production in collisions of transversely polarized hadrons. We use a recently
developed projection technique for treating the phase space integrals in the
presence of the cos(2Phi) azimuthal-angular dependence associated with
transverse polarization. Our phenomenological results show that the double-spin
asymmetry A_TT^pi for neutral-pion production is expected to be very small for
polarized pp scattering at RHIC and could be much larger for the proposed
experiments with an asymmetric pbar-p collider at the GSIComment: 7 pages, 5 figure
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