A two-parameter family of complex Hadamard matrices of order 6 induced by hypocycloids

Constructions of Hadamard matrices from smaller blocks is a well-known technique in the theory of real Hadamard matrices: tensoring Hadamard matrices and the classical arrays of Williamson, Ito are all procedures involving smaller order building blocks. We apply a new block-construction for order 6 to obtain a previously unknown 2-dimensional family of complex Hadamard matrices. Our results extend the families D_6(t) and B_6(t) found by various authors recently. As a direct application the existence of a 2-parameter family of MUB-triplets of order 6 is shown.