Two-loop quark and gluon form factors in dimensional regularisation

We compute the two-loop corrections to the massless quark form factor γ∗→qq¯ and gluon form factor H→gg to all orders in the dimensional regularisation parameter ε=(4−d)/2. The two-loop contributions to the form factors are reduced to linear combinations of master integrals, which are computed in a closed form, expressed as Γ-functions and generalised hypergeometric functions of unit argument. Using the newly developed HypExp-package, these can be expanded to any desired order, yielding Laurent expansions in ε. We provide expansions of the form factors to order ε2, as required for ultraviolet renormalisation and infrared factorisation of the three-loop form factors.