One of these objects can couple with a quasiparticle of plasma oscillation 
One of these objects can couple with a quasiparticle of plasma oscillation known as a plasmon to form a polariton. Low-energy annihilation produces at least two of these particles, which are represented by wavy lines in Feynman diagrams. The momenta of these particles may be calculated by multiplying the reduced Planck constant by the wave vector. Besides the gluon, this boson is the only massless particle in the Standard Model, and it mediates the electromagnetic force. This particle's speed in a vacuum, c, cannot be exceeded by any matter. For 10 points, name this elementary particle, the quantum of light.
One of these objects can couple with a quasiparticle of plasma oscillation known as a plasmon to form a polariton.
{photon}s [prompt on “gamma”]