Quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution

Abstract We apply the formalism developed earlier [1, 2] for studying transverse momentum dependent parton distribution functions (TMDs) at small Bjorken x to construct the small-x asymptotics of the quark Sivers function. First, we explicitly construct the complete fundamental “polarized Wilson lin...

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Autores principales: Yuri V. Kovchegov, M. Gabriel Santiago
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spelling oai:doaj.org-article:c1997b71cfd7463882c22f125025c28a2021-12-05T12:25:00ZQuark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution10.1007/JHEP11(2021)2001029-8479https://doaj.org/article/c1997b71cfd7463882c22f125025c28a2021-11-01T00:00:00Zhttps://doi.org/10.1007/JHEP11(2021)200https://doaj.org/toc/1029-8479Abstract We apply the formalism developed earlier [1, 2] for studying transverse momentum dependent parton distribution functions (TMDs) at small Bjorken x to construct the small-x asymptotics of the quark Sivers function. First, we explicitly construct the complete fundamental “polarized Wilson line” operator to sub-sub-eikonal order: this object can be used to study a variety of quark TMDs at small x. We then express the quark Sivers function in terms of dipole scattering amplitudes containing various components of the “polarized Wilson line” and show that the dominant (eikonal) term which contributes to the quark Sivers function at small x is the spin-dependent odderon, confirming the re- cent results of Dong, Zheng and Zhou [3]. Our conclusion is also similar to the case of the gluon Sivers function derived by Boer, Echevarria, Mulders and Zhou [4] (see also [5]). We also analyze the sub-eikonal corrections to the quark Sivers function using the constructed “polarized Wilson line” operator. We derive new small-x evolution equations re-summing double-logarithmic powers of α s ln2(1/x) with α s the strong coupling constant. We solve the corresponding novel evolution equations in the large-N c limit, obtaining a sub-eikonal correction to the spin-dependent odderon contribution. We conclude that the quark Sivers function at small x receives contributions from two terms and is given by f 1 T ⊥ q x k T 2 = C O x k T 2 1 x + C 1 k T 2 1 x 0 + ⋯ $$ {f}_{1T}^{\perp q}\left(x,{k}_T^2\right)={C}_O\left(x,{k}_T^2\right)\frac{1}{x}+{C}_1\left({k}_T^2\right){\left(\frac{1}{x}\right)}^0+\cdots $$ with the function C O (x, k T 2 $$ {k}_T^2 $$ ) varying slowly with x and the ellipsis denoting the subasymptotic and sub-sub-eikonal (order-x) corrections.Yuri V. KovchegovM. Gabriel SantiagoSpringerOpenarticlePerturbative QCDResummationNuclear and particle physics. Atomic energy. RadioactivityQC770-798ENJournal of High Energy Physics, Vol 2021, Iss 11, Pp 1-59 (2021)
institution DOAJ
collection DOAJ
language EN
topic Perturbative QCD
Resummation
Nuclear and particle physics. Atomic energy. Radioactivity
QC770-798
spellingShingle Perturbative QCD
Resummation
Nuclear and particle physics. Atomic energy. Radioactivity
QC770-798
Yuri V. Kovchegov
M. Gabriel Santiago
Quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution
description Abstract We apply the formalism developed earlier [1, 2] for studying transverse momentum dependent parton distribution functions (TMDs) at small Bjorken x to construct the small-x asymptotics of the quark Sivers function. First, we explicitly construct the complete fundamental “polarized Wilson line” operator to sub-sub-eikonal order: this object can be used to study a variety of quark TMDs at small x. We then express the quark Sivers function in terms of dipole scattering amplitudes containing various components of the “polarized Wilson line” and show that the dominant (eikonal) term which contributes to the quark Sivers function at small x is the spin-dependent odderon, confirming the re- cent results of Dong, Zheng and Zhou [3]. Our conclusion is also similar to the case of the gluon Sivers function derived by Boer, Echevarria, Mulders and Zhou [4] (see also [5]). We also analyze the sub-eikonal corrections to the quark Sivers function using the constructed “polarized Wilson line” operator. We derive new small-x evolution equations re-summing double-logarithmic powers of α s ln2(1/x) with α s the strong coupling constant. We solve the corresponding novel evolution equations in the large-N c limit, obtaining a sub-eikonal correction to the spin-dependent odderon contribution. We conclude that the quark Sivers function at small x receives contributions from two terms and is given by f 1 T ⊥ q x k T 2 = C O x k T 2 1 x + C 1 k T 2 1 x 0 + ⋯ $$ {f}_{1T}^{\perp q}\left(x,{k}_T^2\right)={C}_O\left(x,{k}_T^2\right)\frac{1}{x}+{C}_1\left({k}_T^2\right){\left(\frac{1}{x}\right)}^0+\cdots $$ with the function C O (x, k T 2 $$ {k}_T^2 $$ ) varying slowly with x and the ellipsis denoting the subasymptotic and sub-sub-eikonal (order-x) corrections.
format article
author Yuri V. Kovchegov
M. Gabriel Santiago
author_facet Yuri V. Kovchegov
M. Gabriel Santiago
author_sort Yuri V. Kovchegov
title Quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution
title_short Quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution
title_full Quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution
title_fullStr Quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution
title_full_unstemmed Quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution
title_sort quark sivers function at small x: spin-dependent odderon and the sub-eikonal evolution
publisher SpringerOpen
publishDate 2021
url https://doaj.org/article/c1997b71cfd7463882c22f125025c28a
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AT mgabrielsantiago quarksiversfunctionatsmallxspindependentodderonandthesubeikonalevolution
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