Multipoint conformal blocks in the comb channel

Conformal blocks are the building blocks for correlation functions in conformal field theories. The four-point function is the most well-studied case. We consider conformal blocks for n-point correlation functions. For conformal field theories in dimensions d = 1 and d = 2, we use the shadow formalism to compute n-point conformal blocks, for arbitrary n, in a particular channel which we refer to as the comb channel. The result is expressed in terms of a multivariable hypergeometric function, for which we give series, differential, and integral representations. In general dimension d we derive the 5-point conformal block, for external and exchanged scalar operators.