Numerical Approach to Evolution Equations for Generalized Parton Distributions

We present a numerical code in Python to calculate the evolution equation in pertur- bative Quantum Chromodynamics (PQCD) for both the parton distributions which are obtained in inclusive deep inelastic scattering experiments, and the generalized parton distributions which can be extracted from deeply virtual exclusive experi- ments. To solve the integro-differential equations, we adopt the Adams method as an alternative technique to the standard Runge-Kutta algorithm. We compare the relative efficiency of various algorithms for solving the PQCD evolution calculation. The methods are: backward difference, Adams and Runge-Kutta (RK4) We found that the Adams method is the most efficient one in that it decreases the calculation time about four times compared to RK4, while leaving the calculational error about the same.These studies provide an initial step to calculate GPDs evolution.