Muoproduction of J and gluon helicity distribution functions

1984 ◽  
Vol 81 (4) ◽  
pp. 661-679 ◽  
Author(s):  
A. D. Watson
Keyword(s):  
Distribution Functions ◽  
Helicity Distribution ◽  
Gluon Helicity

scholarly journals Measurement of Longitudinal Single-Spin Asymmetry for W± Production in Polarized Proton+Proton Collisions at STAR

2020 ◽  
Vol 1643 (1) ◽  
pp. 012197
Author(s):  
Qinghua Xu
Keyword(s):  
Spin Asymmetry ◽  
Global Analysis ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Distribution Functions ◽  
Single Spin Asymmetry ◽  
Nucleon Spin ◽  
Single Spin ◽  
Double Spin ◽  
Helicity Distribution

Abstract The contribution from the sea quark polarization to the nucleon spin is an important piece for the complete understanding of the nucleon spin structure. The production of W ± bosons in longitudinally polarized p+p collisions at the RHIC collider at Brookhaven National Laboratory provides a unique probe of the sea quark polarization, through the parity-violating single-spin asymmetry, AL . At the STAR experiment, the W bosons that decay through the W → ev channel at mid-rapidity (|η <1.3) can be effectively determined with the Electromagnetic Calorimeters and Time Projection Chamber. The STAR measurements of AL for W boson from datasets taken in 2011 and 2012 at s =510 GeV have been included in the global analysis of polarized parton distribution functions, and provided significant constraints on the helicity distribution functions of u ¯ and d ¯ quarks. The final AL results from 2013 STAR data sample are reported, which is about three times larger than the total integrated luminosity of previous years. The combined results of AL for 2011-2013 data are also given. A flavor asymmetry of light sea quark helicity distribution, Δ u ¯ ( x )   −   Δ d ¯ ( x ) > 0 , is confirmed from a re-weighting of global analysis NNPDFpol1.1 after including the new AL results. In addition, results on the double-spin asymmetries ALL for W ±, and AL for Z/γ* production are also reported.

scholarly journals Small x Asymptotics of the Quark and Gluon Helicity Distributions

2018 ◽  
Vol 172 ◽  
pp. 03006
Author(s):  
Yuri V. Kovchegov ◽  
Daniel Pitonyak ◽  
Matthew D. Sievert
Keyword(s):  
Perturbative Qcd ◽  
Evolution Equations ◽  
Leading Order ◽  
Helicity Distribution ◽  
Small X ◽  
Gluon Helicity

We determine the small-x asymptotics of the gluon helicity distribution in a proton at leading order in perturbative QCD at large Nc. To achieve this, we begin by evaluating the dipole gluon helicity TMD at small x. We then construct and solve novel small-x large-Nc evolution equations for the operator related to the dipole gluon helicity TMD. Our main result is the small-x asymptotics for the quark helicity distribution

scholarly journals Gluon Helicity Distribution at Small x

2018 ◽  
Author(s):  
Yuri Kovchegov ◽  
Daniel Pitonyak ◽  
Matthew Sievert
Keyword(s):  
Helicity Distribution ◽  
Small X ◽  
Gluon Helicity

scholarly journals Small-x asymptotics of the gluon helicity distribution

2017 ◽  
Vol 2017 (10) ◽  
Author(s):  
Yuri V. Kovchegov ◽  
Daniel Pitonyak ◽  
Matthew D. Sievert
Keyword(s):  
Helicity Distribution ◽  
Small X ◽  
Gluon Helicity

Computer processing of high-resolution images of periodic specimens

1986 ◽  
Vol 44 ◽  
pp. 2-5
Author(s):  
W. Chiu ◽  
M.F. Schmid ◽  
T.-W. Jeng
Keyword(s):  
High Resolution ◽  
Fourier Transforms ◽  
Complex Structure ◽  
Distribution Functions ◽  
Multiple Image ◽  
Cryo Electron Microscopy ◽  
Structure Factors ◽  
Unit Cells ◽  
High Resolution Images ◽  
Phase Probability Distribution

Cryo-electron microscopy has been developed to the point where one can image thin protein crystals to 3.5 Å resolution. In our study of the crotoxin complex crystal, we can confirm this structural resolution from optical diffractograms of the low dose images. To retrieve high resolution phases from images, we have to include as many unit cells as possible in order to detect the weak signals in the Fourier transforms of the image. Hayward and Stroud proposed to superimpose multiple image areas by combining phase probability distribution functions for each reflection. The reliability of their phase determination was evaluated in terms of a crystallographic “figure of merit”. Grant and co-workers used a different procedure to enhance the signals from multiple image areas by vector summation of the complex structure factors in reciprocal space.

Obtaining Normalized Atomic Radial Distribution Functions from EELFS Spectra

1997 ◽  
Vol 7 (C2) ◽  
pp. C2-577-C2-578 ◽  
Author(s):  
D. V. Surnin ◽  
D. E. Denisov ◽  
Yu. V. Ruts ◽  
P. M. Knjazev
Keyword(s):  
Radial Distribution ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Atomic Radial Distribution
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