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Apr 13 – 16, 2021
US/Eastern timezone

Helicity at Small x: LLA Corrections

Apr 16, 2021, 2:30 PM
20m

Speaker

Yossathorn Tawabutr (The Ohio State University)

Description

The small-$x$ quark helicity evolution equations at double-logarithmic order, with the kernel $\sim \alpha_s\ln^2 (1/x)$, had been derived previously, and the equations were solved analytically at large $N_c$ and numerically at large $N_c$ and $N_f$. (Here, $N_c$ and $N_f$ are the numbers of quark colors and flavors, respectively.) In this work, we derive the single-logarithmic corrections to the double-logarithmic equations derived previously, that is, we find the correction to order $\alpha_s\ln (1/x)$ of the evolution kernel. The new equations include the effects of the running coupling and the unpolarized small-$x$ evolution, both of which are parametrically significant at single-logarithmic order. The large-$N_c$ and large-$N_c \& N_f$ approximations to the equation are computed. Their solution will provide a more precise estimate of the quark helicity distribution at small $x$, contributing to the resolution of the proton spin puzzle.

Primary authors

Yossathorn Tawabutr (The Ohio State University) Yuri Kovchegov (The Ohio State University) Andrey Tarasov (The Ohio State University)

Presentation materials