New differential equations for on-shell loop integrals

Understand

We present a novel type of differential equations for on-shell loop integrals.

• The equations are second-order and importantly, they reduce the loop level by one, so that they can be solved iteratively in the loop order.
• We present several infinite series of integrals satisfying such iterative differential equations.
• The differential operators we use are best written using momentum twistor space.