Update of the solar neutrino oscillation analysis with the 766 Ty KamLAND spectrum
Abhijit Bandyopadhyay, Sandhya Choubey, Srubabati Goswami, S.T. Petcov, D.P. Roy
Abstract
We investigate the impact of the 766.3 Ty KamLAND spectrum data on the determination of the solar neutrino oscillation parameters. We show that the observed spectrum distortion in the KamLAND experiment firmly establishes
Δ
m
2
21
to lie in the low-LMA solution region. The high-LMA solution is excluded at more than 4
σ
by the global solar neutrino and KamLAND spectrum data. The maximal solar neutrino mixing is ruled out at
6σ
level. The
3σ
allowed region in the
Δ
m
2
21
−
sin
2
θ
12
plane is found to be remarkably stable with respect to leaving out the data from one of the solar neutrino experiments from the global analysis. We perform a three flavor neutrino oscillation analysis of the global solar neutrino and KamLAND spectrum data as well. The
3σ
upper limit on
sin
2
θ
13
is found to be
sin
2
θ
13
<0.055
. We derive predictions for the CC to NC event rate ratio and day-night (D-N) asymmetry in the CC event rate, measured in the SNO experiment, and for the suppression of the event rate in the BOREXINO and LowNu experiments. Prospective high precision measurements of the solar neutrino oscillation parameters are also discussed.