PT Journal
AU Borexino Collaboration (Bellini, Gea
   Pena-Garay, C
TI Absence of a day-night asymmetry in the Be-7 solar neutrino rate in Borexino
SO Physics Letters B
JI Phys. Lett. B
PY 2012
BP 22
EP 26
VL 707
IS 1
DI 10.1016/j.physletb.2011.11.025
LA English
DE Solar neutrinos; Day-night effect; CPT violation; Neutrino oscillations
AB We report the result of a search for a day-night asymmetry in the Be-7 solar neutrino interaction rate in the Borexino detector at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The measured asymmetry is A(dn) = 0.001 +/- 0.012 (stat) +/- 0.007 (syst), in agreement with the prediction of MSW-LMA solution for neutrino oscillations. This result disfavors MSW oscillations with mixing parameters in the LOW region at more than 8.5 sigma. This region is, for the first time, strongly disfavored without the use of reactor anti-neutrino data and therefore the assumption of CPT symmetry. The result can also be used to constrain some neutrino oscillation scenarios involving new physics.
ER