Constraining neutrino oscillation parameters with current solar and atmospheric data

We analyse the impact of recent solar and atmospheric data in the determination of the neutrino oscillation parameters, taking into account that both the solar νe and the atmospheric νμ may convert to a mixture of active and sterile neutrinos. In addition to the recent SNO neutral current (NC), spectral and day/night data we add the latest 1496day solar and 1489-day atmospheric Super-K neutrino data samples. By investigating in detail the impact of the recent SNO NC, spectral and day/night data, we confirm the clear preference of the LMA solution of the solar neutrino problem and obtain that the LOW, VAC, SMA solutions are disfavoured with a ∆χ = 9, 9, 23, respectively. Furthermore, we find that the global solar data constrains the admixture of a sterile neutrino to be less than 45% at 99% C.L.. A pure sterile solution is ruled out with respect to the active one at 99.996% C.L.. By performing an improved fit of the atmospheric data, we also update the corresponding regions of oscillation parameters. We find that the recent atmospheric Super-K (1489-day) and MACRO data have a strong impact on constraining a sterile component in atmospheric oscillations: if the νμ is restricted to the atmospheric mass states only a sterile admixture of 16% is allowed at 99% C.L., while a bound of 35% is obtained in the unconstrained case. Pure sterile oscillations are disfavoured with a ∆χ = 34.6 compared to the pure active case.