Mass spectrum of chiral ten-dimensionalN=2supergravity onS5

We discuss the spontaneous compactification of chiral N=2 ten-dimensional supergravity from ten to five dimensions on $S^5$. Harmonic analysis on $S^5$ is used to compute the complete mass spectrum. Our results indicate that scalars and spinors in different SO(6) multiplets have different masses, even within the ‘‘massless’’ supermultiplet. We show that the conformal diffeomorphisms, which remain after imposing certain covariant gauge conditions for the general coordinate invariance, can be used to gauge away twice as many modes as there are gauge parameters. A doubleton multiplet of pure gauge modes is identified, and all modes in the massless supermultiplet lie at the beginning of infinite towers of modes.