Calculating TMDs of a large nucleus: Quasiclassical approximation and quantum evolution
We set up a formalism for calculating transversemomentumdependent parton distribution functions (TMDs) of a large nucleus using the tools of saturation physics. By generalizing the quasiclassical Glauber–Gribov–Mueller/McLerran–Venugopalan approximation to allow for the possibility of spin–orbit coupling, we show how any TMD can be calculated in the saturation framework. This can also be applied to the TMDs of a proton by modeling it as a large “nucleus.” To illustrate our technique, we calculate the quark TMDs of an unpolarized nucleus at largex: the unpolarized quark distribution and the quark Boer–Mulders distribution. Here, we observe that spin–orbit coupling leads to mixing between different TMDs of the nucleus and of the nucleons. We then consider the evolution of TMDs: at largex, in the doublelogarithmic approximation, we obtain the Sudakov form factor. At smallx the evolution of unpolarizedtarget quark TMDs is governed by BK/JIMWLK evolution, while the smallx evolution of polarizedtarget quark TMDs appears to be dominated by the QCD Reggeon.
 Authors:

^{[1]};
^{[2]}
 The Ohio State Univ., Columbus, OH (United States)
 Brookhaven National Lab. (BNL), Upton, NY (United States)
 Publication Date:
 Report Number(s):
 BNL1120202016JA
Journal ID: ISSN 05503213; R&D Project: 08870; KB0301020
 Grant/Contract Number:
 SC00112704; SC0012704
 Type:
 Published Article
 Journal Name:
 Nuclear Physics. B
 Additional Journal Information:
 Journal Volume: 903; Journal Issue: C; Journal ID: ISSN 05503213
 Publisher:
 Elsevier
 Research Org:
 Brookhaven National Laboratory (BNL), Upton, NY (United States)
 Sponsoring Org:
 USDOE Office of Science (SC), Nuclear Physics (NP) (SC26)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 73 NUCLEAR PHYSICS AND RADIATION PHYSICS
 OSTI Identifier:
 1234126
 Alternate Identifier(s):
 OSTI ID: 1253276
Kovchegov, Yuri V., and Sievert, Matthew D.. Calculating TMDs of a large nucleus: Quasiclassical approximation and quantum evolution. United States: N. p.,
Web. doi:10.1016/j.nuclphysb.2015.12.008.
Kovchegov, Yuri V., & Sievert, Matthew D.. Calculating TMDs of a large nucleus: Quasiclassical approximation and quantum evolution. United States. doi:10.1016/j.nuclphysb.2015.12.008.
Kovchegov, Yuri V., and Sievert, Matthew D.. 2015.
"Calculating TMDs of a large nucleus: Quasiclassical approximation and quantum evolution". United States.
doi:10.1016/j.nuclphysb.2015.12.008.
@article{osti_1234126,
title = {Calculating TMDs of a large nucleus: Quasiclassical approximation and quantum evolution},
author = {Kovchegov, Yuri V. and Sievert, Matthew D.},
abstractNote = {We set up a formalism for calculating transversemomentumdependent parton distribution functions (TMDs) of a large nucleus using the tools of saturation physics. By generalizing the quasiclassical Glauber–Gribov–Mueller/McLerran–Venugopalan approximation to allow for the possibility of spin–orbit coupling, we show how any TMD can be calculated in the saturation framework. This can also be applied to the TMDs of a proton by modeling it as a large “nucleus.” To illustrate our technique, we calculate the quark TMDs of an unpolarized nucleus at largex: the unpolarized quark distribution and the quark Boer–Mulders distribution. Here, we observe that spin–orbit coupling leads to mixing between different TMDs of the nucleus and of the nucleons. We then consider the evolution of TMDs: at largex, in the doublelogarithmic approximation, we obtain the Sudakov form factor. At smallx the evolution of unpolarizedtarget quark TMDs is governed by BK/JIMWLK evolution, while the smallx evolution of polarizedtarget quark TMDs appears to be dominated by the QCD Reggeon.},
doi = {10.1016/j.nuclphysb.2015.12.008},
journal = {Nuclear Physics. B},
number = C,
volume = 903,
place = {United States},
year = {2015},
month = {12}
}