Distinguishing spins at the LHC using bound state signals

A pair of new colored particles produced near the threshold can form a bound state and then annihilate into standard model particles. In this paper we show how the bound state signals can distinguish between two scenarios that have similar particle content and interactions but different spins, such as the minimal supersymmetric standard model (MSSM) and universal extra dimensions (UED). We find, for example, that bound states of KK gluons (KK gluonia) have an order of magnitude larger cross sections than gluinonia and they may be detectable as resonances in the $b\bar b$, $t\bar t$ or $\gamma\gamma$ channels if the KK gluon is very light and sufficiently long-lived. KK gluonia can be distinguished from gluinonia by their much larger cross sections and distinct angular distributions. Similarly, KK quarkonia can be distinguished from squarkonia by the size of their diphoton cross section and by their dilepton signals. Since many of our results are largely determined by gauge interactions, they will be useful for many other new physics scenarios as well.