CMB Polarization Systematics in data analysis

We develop a formalism to include polarimeter calibration uncertainties in CMB data analysis and apply it to the B2K dataset, finding a polarization rotation angle α=−4.3°±4.1°. We also investigate the expected performances of future space borne experiment, finding that an overall miscalibration larger then 1° for Planck and 0.2° for EPIC, if not properly taken into account, will produce a bias on the constraints on the cosmological parameters and could misleadingly suggest the presence of a GW background.