Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Cos(4 phi) azimuthal anisotropy in small-x DIS dijet production beyond the leading power TMD limit

Adrian Dumitru, Vladimir Skokov

TL;DR

The paper addresses azimuthal anisotropies in small-x DIS dijet production beyond the leading TMD limit. It develops a fourth-order expansion of the quadrupole operator, identifies the cos 4phi azimuthal harmonic, and derives Phi2 as the key operator-valued quantity, with analytic results in a Gaussian large-Nc (MV) model. The results show cos 4phi is suppressed by 1/P^2 relative to cos 2phi but can be potentially observed at future EIC, and provide a framework for including small-x evolution in Phi2. Together, they extend the understanding of angular correlations in high-energy QCD and quantify beyond-leading-power corrections to TMD-based predictions.

Abstract

We determine the first correction to the quadrupole operator in high-energy QCD beyond the TMD limit of Weizsaecker-Williams and linearly polarized gluon distributions. These functions give rise to isotropic resp. ~ cos 2 phi angular distributions in DIS dijet production. On the other hand, the correction produces a ~ cos 4 phi angular dependence which is suppressed by one additional power of the dijet transverse momentum scale (squared) P^2.

Cos(4 phi) azimuthal anisotropy in small-x DIS dijet production beyond the leading power TMD limit

TL;DR

The paper addresses azimuthal anisotropies in small-x DIS dijet production beyond the leading TMD limit. It develops a fourth-order expansion of the quadrupole operator, identifies the cos 4phi azimuthal harmonic, and derives Phi2 as the key operator-valued quantity, with analytic results in a Gaussian large-Nc (MV) model. The results show cos 4phi is suppressed by 1/P^2 relative to cos 2phi but can be potentially observed at future EIC, and provide a framework for including small-x evolution in Phi2. Together, they extend the understanding of angular correlations in high-energy QCD and quantify beyond-leading-power corrections to TMD-based predictions.

Abstract

We determine the first correction to the quadrupole operator in high-energy QCD beyond the TMD limit of Weizsaecker-Williams and linearly polarized gluon distributions. These functions give rise to isotropic resp. ~ cos 2 phi angular distributions in DIS dijet production. On the other hand, the correction produces a ~ cos 4 phi angular dependence which is suppressed by one additional power of the dijet transverse momentum scale (squared) P^2.

Paper Structure

This paper contains 7 sections, 45 equations, 2 figures.

Table of Contents

  1. Introduction
  2. Extracting the azimuthal angular components of the quadrupole operator
  3. Gaussian approximation
  4. Dijet cross section in DIS
  5. Summary
  6. Useful Integrals
  7. Power corrections to the isotropic and $\cos 2\phi$ contributions

Figures (2)

  • Figure 1: The functions $xG^{(1)}(q^2)$, $xh^{(1)}(q^2)$ and $\Phi_2(q^2)$ in the MV model. These functions determine the amplitudes of the $\cos 2n\phi$ contributions to the dijet angular distributions for $n=0$, 1, 2, respectively. See text for details.
  • Figure 2: $\left< \cos 2\phi\right>$ and $\left< \cos 4\phi\right>$ in $\gamma_L^*+A\to q+\bar{q}$ dijet production from the MV model. See text for details.