Photoproduction of three jets in the CGC: gluon TMDs and dilute limit

Understand

We study the process $\gamma A \to q \bar{q} g+X$ in the Color Glass Condensate (CGC) effective theory.

• After obtaining the cross section, we consider two kinematic limits which are encompassed in our result.
• In the so-called correlation limit, the vector sum of the transverse momenta of the three outgoing particles is small with respect to the individual transverse momenta; the cross section then simplifies considerably and can be written in a factorized form, sensitive to both the unpolarized and linearly-polarized Weizs\"acker-Williams transverse momentum dependent gluon distribution function (gluon TMD).
• The second limit of the CGC cross section that we consider is the dilute limit, which we obtain after performing a weak-field expansion; we recover a typical linear-regime expression, involving a single unintegrated gluon distribution function.