Color-kinematics duality and double-copy for form factors

Color-kinematics duality and double-copy for form factors

Gravity amplitudes are closely linked to gauge theory amplitudes via the double copy as "gravity=gauge^2", in which the color-kinematics (CK) duality for gauge theory amplitudes plays a a crucial role. Given the huge success of studying the CK duality and double-copy for amplitudes, it is natural to ask whether we can extend these properties to other quantities, such as form factors. In this talk, we will talk about the CK duality structure for gauge theory form factors and how to double copy them. The CK duality provides an efficient tool constructing high-loop form factors, and we discuss some properties accordingly. Besides, novel features arise when performing double copy for form factors: for example, spurious poles in gauge amplitudes are made real via double copy.