Spin Discrimination in Three-Body Decays

Understand

The identification of the correct model for physics beyond the Standard Model requires the determination of the spin of new particles.

• We investigate to which extent the spin of a new particle $X$ can be identified in scenarios where it decays dominantly in three-body decays $X\to f\bar{f} Y$.
• Here we assume that $Y$ is a candidate for dark matter and escapes direct detection at a high energy collider such as the LHC.
• We show that in the case that all intermediate particles are heavy, one can get information on the spins of $X$ and $Y$ at the LHC by exploiting the invariant mass distribution of the two standard model fermions.