B-Mode signature

Inflationary gravity waves leave a unique imprint on the polarizaiton of the CMB. The pertubations in the primoridal space-time fluid come in three flavors, scalar, vector, and tensor modes. The scalar modes are responsible for the now-familiar acoustic-peak spectrum measured by the WMAP satellite. Vector modes decay exponentialy after they are formed, and it is believed that they now leave no signature. Tensor modes are uniquely produced in the inflationary scenario and leave a distinct signal in the CMB. Tensor modes have no handedness, and hence should not leave any signal with handesness in the CMB. Tensor modes do have handedness, and therefore can impart handedness to the CMB.
Polarization maps are a vector fields, so it is natural to describe them in terms of E and B modes inspired by vector field descriptions in E&M. B modes are the component with curl.