The ubiquitous nature of the horizontal branch second U-jump -: A link with the Blue Hook scenario?

In a previous paper we reported on a discontinuity in the extreme horizontal branch (EHB) of the Galactic globular cluster NGC 6752. which we called the second U-jump. This feature was attributed to a combination of post zero-age horizontal branch evolution and diffusion effects. In this follow-up study we analyze other EHB clusters and show that the second. U-junip is a common feature among EHB clusters reaching T-eff greater than or equal to 23 000 K, and that its onset in different clusters converged, around T-eff similar to 21000 +/- 3000 K. We also present near-ultraviolet diagrams of omegaCen and NGC 2808, the only two objects with spectroscopically confirmed blue hook stars (T-eff greater than or equal to 35 000 K). We confirm predictions of a photometric discontinuity separatin2 late from early-helium flashers. Moreover, we present empirical evidence that the second U-jump population might be mainly composed of early-helium flashers. Lastly, we revisit the discussion on the ubiquitous nature of the gaps and jumps so far identified in the blue HB tails, suggesting a possible discrete nature of the distribution in temperature of the HB stars.