Unparticle self-interactions and their collider implications

In unparticle physics, operators of the conformal sector have self-interactions, and these are unsuppressed for strong coupling. The 3-point interactions are completely determined by conformal symmetry, up to a constant. We do not know of any theoretical upper bounds on this constant. Imposing current experimental constraints, we find that these interactions mediate spectacular collider signals, such as pp→U→UU→γγγγ, γγZZ, $ZZZZ$, γγl⁺l^-, ZZl⁺l^-, and $4l$, with cross sections of picobarns or larger at the large hadron collider. Self-interactions may therefore provide the leading discovery prospects for unparticle physics.