Publications
Publication Information
| Title | Helicity evolution at small x : Revised asymptotic results at large N c and N f |
| Authors | Daniel Adamiak, Yuri Kovchegov, Yossathorn Tawabutr |
| JLAB number | JLAB-THY-23-3922 |
| LANL number | arXiv:2306.01651 |
| Other number | DOE/OR/23177-7179 |
| Document Type(s) | (Journal Article) |
| Associated with EIC: | No |
| Supported by Jefferson Lab LDRD Funding: | No |
| Funding Source: | Nuclear Physics (NP) |
|
Journal Compiled for Physical Review D Volume 108 Page(s) 054005 | |
| Publication Abstract: | We present a numerical solution of the revised version [J. High Energy Phys. 07 (2022) 095] of the small- x helicity evolution equations from [J. High Energy Phys. 01 (2016) 072, Phys. Rev. D 99, 054032 (2019)] at large N c and N f . (Here N c and N f are the numbers of quark colors and flavors, respectively.) The evolution equations are double-logarithmic in the Bjorken x variable, resumming powers of ? s ln 2 ( 1 / x ) with ? s the strong coupling constant. The large- N c & N f evolution we consider includes contributions of small- x quark emissions and is thus more realistic than the large- N c one, which only involves gluon emissons. The evolution equations [J. High Energy Phys. 07 (2022) 095, J. High Energy Phys. 01 (2016) 072, Phys. Rev. D 99, 054032 (2019)] are written for the so-called ?polarized dipole amplitudes,? which are related to the helicity distribution functions and the g 1 structure function. Unlike the previously reported solution [J. High Energy Phys. 08 (2020) 014] of the earlier version of helicity evolution equations at large N c & N f [J. High Energy Phys. 01 (2016) 072, Phys. Rev. D 99, 054032 (2019)], our solution does not exhibit periodic oscillations in ln ( 1 / x ) for N f < 2 N c , while only showing occasional sign reversals. For N f = 2 N c , we report oscillations with ln ( 1 / x ) , similar to those found earlier in [J. High Energy Phys. 08 (2020) 014]. We determine the intercept of our evolution for N f < 2 N c as well as the parameters of the oscillatory behavior for N f = 2 N c . We compare our results to the existing resummation [Z. Phys. C 72, 627 (1996)] and finite-order calculations for helicity-dependent quantities in the literature. |
| Experiment Numbers: | |
| Group: | THEORY CENTER |
| Document: | |
| DOI: | https://doi.org/10.1103/PhysRevD.108.054005 |
| Accepted Manuscript: | PhysRevD.108.054005.pdf |
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