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Title: Small- x helicity evolution: An operator treatment

Abstract

We rederive the small-x evolution equations governing quark helicity distribution in a proton using solely an operator-based approach. In our previous works on the subject, the evolution equations were derived using a mix of diagrammatic and operator-based methods. In this work, we rederive the double-logarithmic small-x evolution equations for quark helicity in terms of the “polarized Wilson lines,” the operators consisting of light-cone Wilson lines with one or two noneikonal local operator insertions which bring in helicity dependence. For the first time we give explicit and complete expressions for the quark and gluon polarized Wilson line operators, including insertions of both the gluon and quark subeikonal operators. We show that the double-logarithmic small-x evolution of the “polarized dipole amplitude” operators, made out of regular light-cone Wilson lines along with the polarized ones constructed here, reproduces the equations derived in our earlier works. The method we present here can be used as a template for determining the small-x asymptotics of any transverse momentum-dependent (TMD) quark (or gluon) parton distribution functions (PDFs), and is not limited to helicity.

Authors:
;
Publication Date:
Research Org.:
The Ohio State Univ., Columbus, OH (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP)
OSTI Identifier:
1503931
Alternate Identifier(s):
OSTI ID: 1604162
Grant/Contract Number:  
SC0004286; AC52-06NA25396
Resource Type:
Published Article
Journal Name:
Physical Review. D.
Additional Journal Information:
Journal Name: Physical Review. D. Journal Volume: 99 Journal Issue: 5; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Kovchegov, Yuri V., and Sievert, Matthew D. Small- x helicity evolution: An operator treatment. United States: N. p., 2019. Web. doi:10.1103/PhysRevD.99.054032.
Kovchegov, Yuri V., & Sievert, Matthew D. Small- x helicity evolution: An operator treatment. United States. https://doi.org/10.1103/PhysRevD.99.054032
Kovchegov, Yuri V., and Sievert, Matthew D. Fri . "Small- x helicity evolution: An operator treatment". United States. https://doi.org/10.1103/PhysRevD.99.054032.
@article{osti_1503931,
title = {Small- x helicity evolution: An operator treatment},
author = {Kovchegov, Yuri V. and Sievert, Matthew D.},
abstractNote = {We rederive the small-x evolution equations governing quark helicity distribution in a proton using solely an operator-based approach. In our previous works on the subject, the evolution equations were derived using a mix of diagrammatic and operator-based methods. In this work, we rederive the double-logarithmic small-x evolution equations for quark helicity in terms of the “polarized Wilson lines,” the operators consisting of light-cone Wilson lines with one or two noneikonal local operator insertions which bring in helicity dependence. For the first time we give explicit and complete expressions for the quark and gluon polarized Wilson line operators, including insertions of both the gluon and quark subeikonal operators. We show that the double-logarithmic small-x evolution of the “polarized dipole amplitude” operators, made out of regular light-cone Wilson lines along with the polarized ones constructed here, reproduces the equations derived in our earlier works. The method we present here can be used as a template for determining the small-x asymptotics of any transverse momentum-dependent (TMD) quark (or gluon) parton distribution functions (PDFs), and is not limited to helicity.},
doi = {10.1103/PhysRevD.99.054032},
journal = {Physical Review. D.},
number = 5,
volume = 99,
place = {United States},
year = {Fri Mar 29 00:00:00 EDT 2019},
month = {Fri Mar 29 00:00:00 EDT 2019}
}

Journal Article:
Free Publicly Available Full Text
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https://doi.org/10.1103/PhysRevD.99.054032

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Cited by: 35 works
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