Flavour vs evolution

Created by: tgiani

When working in the flavour basis we want to ensure the integrability of the distributions

q_f = V, V3, V8, T3, T8, T15, x*g, x*sgm 

This means that the distributions

x*q_f =xV, xV3, xV8, xT3, xT8, xT15, x^2*g, x^2*sgm 

should go to 0 at small-x. This integrability constraint can be imposed introducing some lagrange multipliers, adding to the loss function a term like

 \sum_f \sum_i  \lambda_f *( x_i*q_f (x_i,Q_0) )^2

considering a set of small enough x_i