Final-state interactions and single-spin asymmetries in semi-inclusive deep inelastic scattering

Recent measurements from the HERMES and SMC Collaborations show a remarkably large azimuthal single-spin asymmetries A_UL and A_UT of the proton in semi-inclusive pion leptoproduction γ^*(q)p→πX. We show that final-state interactions from gluon exchange between the outgoing quark and the target spectator system lead to single-spin asymmetries in deep inelastic lepton–proton scattering at leading twist in perturbative QCD; i.e., the rescattering corrections are not power-law suppressed at large photon virtuality Q² at fixed x_bj. The existence of such single-spin asymmetries requires a phase difference between two amplitudes coupling the proton target with J^z_p=±1/2 to the same final-state, the same amplitudes which are necessary to produce a nonzero proton anomalous magnetic moment. We show that the exchange of gauge particles between the outgoing quark and the proton spectators produces a Coulomb-like complex phase which depends on the angular momentum L^z of the proton's constituents and is thus distinct for different proton spin amplitudes. The single-spin asymmetry which arises from such final-state interactions does not factorize into a product of distribution function and fragmentation function, and it is not related to the transversity distribution δq(x,Q) which correlates transversely polarized quarks with the spin of the transversely polarized target nucleon.     

Loss of polarization entanglement in a fiber-optic system with polarization mode dispersion in one optical path

We characterize theoretically and experimentally the degradation of polarization entanglement in a fiber-optic entanglement distribution system where one of the optical fibers is exposed to the effects of polarization mode dispersion (PMD). We show gradual reduction of entanglement with increasing PMD and find that the highest PMD tolerance is achieved when the bandwidth of the pump used to generate the entangled photons in a χ((3)) process is approximately half the bandwidth of the quantum channels.     

Deacylative oxidation strategy for the preparation of alpha-functionalized carbonyls

[reaction: see text] alpha-Alkoxylation and amination of carbonyl derivatives is made possible through a unique deacylative coupling reaction that proceeds via in situ Rh-carbene formation and subsequent heteroatom-H (X-H) insertion. Reactions perform optimally with five- and six-membered ring lactone and lactam derivatives using both alcohol and carbamate substrates as coupling partners. Substituted ethylbenzoyl acetate starting materials have also proven to be effective for this oxidative process, affording alpha-functionalized esters under particularly mild and operationally facile conditions.     

Corrosion and Quality

Corrosion is an interaction between a material and its environment that results in deterioration of both. Quality has a wider meaning and designates the suitability of products, management quality and work. Corrosion is a phenomenon, and quality is a philosophical category. The aim of this work is to find common ground between corrosion and quality. We encounter degradation of materials and the environment in everyday life. Corrosion influences the quality of work, products, management, environment and life. The aspects of corrosion correspond to the various meanings of quality. Corrosion costs may be considered as part of the total costs of quality. Corrosion costs are estimated to be as high as 5% of the GNP in various countries.Most corrosion costs can be saved and quality improved by means of control measures, analysis of failures, dissemination of knowledge, and use of monitoring techniques. Anti-corrosion management quality includes design, manufacture, improvement, and control at all stages.Presented at 15th International Conference on Quality in Israel, November 2004