RR Lyrae variables in Galactic Globular Clusters: distribution of   periods and synthetic models
  We present some applications of our Synthetic Horizontal Branches (SHB) simulations, aimed to reproduce the peculiar period distributions of RR Lyrae belonging to the Galactic Globular Clusters M3 and M5. We show some evidence, supporting the importance of SHBs in obtaining parameters such as the mass distribution inside the instability strip. 
M. Castellani, V. Castellani, S. Cassisi and F. Caputo