Confronting solutions to the atmospheric neutrino anomaly involving large angle νμ→νe oscillations with SuperKamiokande and CHOOZ

Neutrino oscillation scenarios involving large angle νμ→νe oscillations are disfavoured in the parameter range Δm2/eV2≳10−3 by recent results from the CHOOZ reactor-based νe disappearance experiment. For this reason we extend our previous work on up-down asymmetries for various oscillation scenarios by computing up-down asymmetries and the R ratio for the entire range of interest of Δm2. Matter effects in the Earth play a crucial role. We perform a χ2 fit to the data. We find that, because of the matter effect, the three-flavour maximal mixing model provides a reasonable fit to SuperKamiokande and CHOOZ data provided that the relevant Δm2 is in the range 4×10−4≲Δm2/eV2≲1.5×10−3.