Conformal higher-spin symmetries in twistor string theory

It is shown that similarly to massless superparticle, classical global symmetry of the Berkovits twistor string action is infinite-dimensional. We identify its superalgebra, whose finite-dimensional subalgebra contains $psl(4\mathrm{\mid }4,\mathbb{R})$ superalgebra. In quantum theory this infinite-dimensional symmetry breaks down to $SL(4\mathrm{\mid }4,\mathbb{R})$ one.