Determination of the θ 23 octant in LBNO
Received: December
Determination of the 23 octant in LBNO
C.R. Das 0 1 2 3 4
Jukka Maalampi 0 1 3 4
Joao Pulido 0 1 4
Sampsa Vihonen 0 1 3 4
Open Access 0 1 4
c The Authors. 0 1 4
0 Navrangpura , Ahmedabad 380 009 , India
1 P. O. Box 35, FIN-40014 Jyvaskyla , Finland
2 Theoretical Physics Division, Physical Research Laboratory
3 University of Jyvaskyla, Department of Physics
4 [25] P. Ballet, private communications, Durham University, U.K
According to the recent results of the neutrino oscillation experiment MINOS, the neutrino mixing angle 23 may not be maximal (45). Two nearly degenerate solutions are possible, one in the lower octant (LO) where 23 < 45, and one in the higher octant (HO) where 23 > 45. Long baseline experiments measuring the e are capable of resolving this degeneracy. In this work we study the potential of the planned European LBNO experiment to distinguish between the LO and HO solutions.
Oscillation; Neutrino Detectors and Telescopes
1 Introduction
2 Numerical analysis
3 Results and discussion
Introduction
of resolving the octant degeneracy.
being unable to exclude any of the two possibilities.
(for a recent analysis, see [11]).
Numerical analysis
21] instead of Monte Carlo simulations.
the LBNO are presented in table 1.
files based on a GEANT4 simulation [22].
Beam power [SPS] (1020 POT/yr)
Beam power [HPPS] (1021 POT/yr)
Baseline length (km)
Running times (yr)
Detection efficiency (%)
Energy resolution (GeV)
Energy window (GeV)
Number of bins
Bin width (GeV)
[0.1, 10.0]
with a resolution of 0.15
E, where E is the neutrino energy in GeV. The cross sections
to tau neutrinos into account better than any previous simulation.
The LBNO experiment is designed to study the electron appearance probabilities
as the intrinsic beam contamination.
computed with the Poissonian function
X 2 Ti Oi 1 ln Ti
The observed events is the category of events that would result from oscillation
pathe sum of events from signal and background components:
Oi = Nisg(0) + Nibg(0),
where Nisg and N bg stand for the numbers of signal and background events.
i
The test values on the other hand stand for event numbers that are computed with
Ti = Nisg()[1 + 11] + Nibg()[1 + 22].
pull(, 0) = min 2(, 0) + 12 + 22 ,
2
corresponds to the normalization error in the LArTPC detectors [11].
sin2 12() sin2 12(0) 2
sin2 213() sin2 213(0) 2
m221() m221(0) 2
m231() m231(0) 2
and (2.5), which is then minimized over the test values:
2 2 2
total(0) = min pull(, 0) + prior(, 0) .
The final 2 value is calculated by minimizing total over all oscillation parameters in
2
2
total may converge, and the absence of CP in equation (2.5) indicates that no such
con2 = total(90 23) total(23).
2 2
determined parameter values. These values are also presented in table 2.
2
function prior and therefore they are both marked with zero. This follows from our choice
Results and discussion
intermediate values.
The contour plots were produced for four different setups: SPS beam with 20 kt
size from 20kt to 70 kt with the same beam power.
worsens it.
be a logical follow-up of the mass hierarchy measurement.
Acknowledgments
versity of Jyvaskyla, for hospitality and partial financial support.
Open Access.
This article is distributed under the terms of the Creative Commons
any medium, provided the original author(s) and source are credited.
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