Flavor Singlet Axial Coupling of the Proton - An Updated Analysis

We present a combined analysis of SESAM and TxL data for the flavor singlet axial coupling G_A^1 of the proton, which is very helpful to stabilize the disconnected signals at small quark masses. From connected and disconnected contributions we use the tadpole improved renormalization constant Z_A and obtain G_A^1=0.21(12).Comment: 3 pages, contribution to LATTICE99 (matrix elements

Finals during COVID-19

The author provides journal entries from March 8, 2020 and March 15, 2020. During this time, she learns that Eastern Washington University (EWU) moved finals week up a week, allowing students to move out for Spring break a week early. She also describes the escalating mitigation steps that resulted in general quarantine and movement of all EWU classes online.https://dc.ewu.edu/covid/1038/thumbnail.jp

Target independence of the `proton spin' effect

Recent work by the author in collaboration with S. Narison and G. Veneziano on the EMC-SMC-SLAC `proton spin' effect is reviewed. This uses a novel approach to deep inelastic scattering in which the matrix elements arising from the OPE are factorised into composite operator propagators and proper vertices. For polarised $\mu p$ scattering, the composite operator propagator is equated to the square root of the first moment of the QCD topological susceptibility, $\sqrt{\chi^\prime(0)}$. We evaluate $\chi^\prime(0)$ using QCD spectral sum rules and find a significant suppression relative to its OZI expectation. This is identified as the source of the violation of the Ellis-Jaffe sum rule for the first moment of the polarised proton structure function $g_1^p$. Our predictions, $\int_0^1 dx g_1^p(x;Q^2=10GeV^2) = 0.143\pm 0.005$ and $\Delta\Sigma =0.353\pm 0.052$, are in excellent agreement with the new SMC data. This supports our earlier conjecture that the suppression in the flavour singlet component of the first moment of $g_1^p$ is a target-independent feature of QCD related to the $U(1)$ anomaly and is not a special property of the proton structure.Comment: 6 pages, SWAT 94-4

A Polarized HERA Collider

A brief review is given of the status of nucleon spin structure functions as determined from polarized deep inelastic lepton-nucleon scatttering, including current outstanding problems. The characteristics of a polarized HERA collider, some of the particle physics topics it could address, and the accelerator physics challenges it must meet are discussed.Comment: 5 Pages, 6 Figures, To be published in the Proceedings of the DIS99 Conference April 1999, DESY Zeuthen, German

The nature and value of cultural policy research for early career researchers.

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Quenching of hadron spectra in DIS on nuclear targets

The multiple scatterings incurred by a hard quark produced in a nuclear medium induce the emission of soft gluons which carry a fraction of the quark energy and eventually affect the hadronization process. Here, the depletion of semi-inclusive hadron spectra in DIS on various nuclei (N, Ne, Cu, Kr) is computed as a function of nu and z to leading order in alpha_s through medium-modified fragmentation functions. Using the transport coefficient q previously determined from Drell-Yan production, the predictions are found to be in good agreement with EMC and HERMES preliminary data. Calculations on Xe targets are also presented and discussed.Comment: 20 pages, 8 figure

Polarized lepton nucleon scattering - summary of the experimental spin sessions at DIS 99

This paper summarizes the contributions to the experimental sessions on polarized lepton nucleon scattering at the DIS 99 workshop. Results are reported about the flavor decomposition of the quark polarization, a first direct measurement of a positive gluon polarization, the observation of a double-spin asymmetry in diffractive rho production, the polarization of lambda hyperons, the observation of transverse single-spin asymmetries and the measurement of the Gerasimov-Drell-Hearn sum rule. Prospects of future fixed target and collider facilities are discussed.Comment: 8 pages, 5 figures, Proc. of the 7th Int. Workshop on Deep Inelastic Scattering and QCD (DIS99), Zeuthen, Germany, April 19-23, 1999, to appear in Nucl. Phys. B (Proc. Suppl.

Hadron Formation in DIS in a nuclear environment

The influence of the nuclear medium on the production of charged hadrons in semi-inclusive deep inelastic scattering has been studied by the HERMES experiment at DESY using 27.5 GeV positrons. A substantial reduction of the multiplicity of charged hadrons and identified charged pions from nuclei relative to that from deuterium has been measured as function of the relevant kinematic variables. The preliminary results on krypton show a larger reduction of the multiplicity ratio $R_M^{h}$ with respect to the one previously measured on nitrogen and suggest a possible modification of the quark fragmentation process in the nuclear environment.Comment: 5 pages, 5 figures, Proceeding of DIS 2001, IX International Workshop on Deep Inelastic Scattering Bologna, 27 April-1 May 200