Determining the Higgs spin and parity in the diphoton decay channel.

We calculate the diphoton distribution in the decay of arbitrary spin-0 and spin-2 bosons produced from gluon fusion, taking into account the fact that gluons inside an unpolarized proton are generally linearly polarized. The gluon polarization brings about a difference in the transverse momentum distribution of positive and negative parity states. At the same time, it causes the azimuthal distribution of the photon pair to be nonisotropic for several spin-2 coupling hypotheses, allowing one to distinguish these from the isotropic scalar and pseudoscalar distributions.