  The very recent Boomerang results give an estimate of unprecedented precision
of the Cosmic Microwave Background anisotropies on sub--degree scales. A
puzzling feature for theoretical cosmology is the low amplitude of the second
acoustic peak. Through a qualitative discussion, we argue that a scarcely
considered category of flat models, with a leptonic asymmetry, a high baryon
density and a low cosmological constant seems to be in very good agreement with
the data, while still being compatible with big bang nucleosynthesis and some
other observational constraints. Although this is certainly not the only way to
explain the data, we believe that these models deserve to be included in
forthcoming likelihood analyses.
