Some remarks on dipole showers and the DGLAP equation

Understand

It has been argued recently that parton showers based on colour dipoles conflict with collinear factorization and do not lead to the correct DGLAP equation.

• We show that this conclusion is based on an inappropriate assumption, namely the choice of the gluon energy as evolution variable.
• We further show numerically that Monte Carlo programs based on dipole showers with "infrared sensible" evolution variables reproduce the DGLAP equation both in asymptotic form as well as in comparison to the leading behaviour of second-order QCD matrix elements.