Scalar boson
A scalar boson is a boson whose spin equals zero. "Boson" means that the particle's wavefunction is symmetric under particle exchange and therefore follows Bose–Einstein statistics. The spin-statistics theorem implies that all bosons have an integer-valued spin; the "scalar" fixes this value to zero. The name "scalar boson" arises from quantum field theory, which demands that fields of spin-zero particles transform like a scalar under Lorentz transformation (i.e. are Lorentz invariant). A pseudoscalar boson is a scalar boson that has odd parity, whereas "regular" scalar bosons have even parity.