Determination of the θ 23 octant in LBNO

Journal of High Energy Physics, Feb 2015

According to the recent results of the neutrino oscillation experiment MINOS, the neutrino mixing angle θ 23 may not be maximal (45°). Two nearly degenerate solutions are possible, one in the lower octant (LO) where θ 23 < 45°, and one in the higher octant (HO) where θ 23 > 45°. Long baseline experiments measuring the ν μ → ν 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.

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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. [4] G.L. Fogli and E. Lisi, Tests of three flavor mixing in long baseline neutrino oscillation experiments, Phys. Rev. D 54 (1996) 3667 [hep-ph/9604415] [INSPIRE]. atmospheric and long baseline neutrino experiments, JHEP 06 (2013) 010 [arXiv:1302.1370] [INSPIRE]. 1350093 [arXiv:1209.5658] [INSPIRE]. experiments: an adequate configuration for LBNO, JHEP 03 (2014) 094 [arXiv:1308.5979] [INSPIRE]. with reactor experiments, arXiv:1405.7482 [INSPIRE]. 112 (2014) 191801 [arXiv:1403.0867] [INSPIRE]. from muon neutrino disappearance in an off-axis beam, Phys. Rev. Lett. 112 (2014) 181801 [arXiv:1403.1532] [INSPIRE]. (2014) 457803 [arXiv:1401.4705] [INSPIRE]. charge imaging experiment?, hep-ph/0402110 [INSPIRE]. Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER), J. Phys. Conf. Ser. 171 (2009) 012020 [arXiv:0908.1286] [INSPIRE]. [15] ISS Detector Working Group collaboration, T. Abe et al., Detectors and flux instrumentation for future neutrino facilities, 2009 JINST 4 T05001 [arXiv:0712.4129] [INSPIRE]. 601 [arXiv:1004.0358] [INSPIRE]. LAGUNA-LBNO, in the proceedings of the 4th International Particle Accelerator Conference CP-violation discovery reach of the LBNO long-baseline neutrino experiment, JHEP 05 (2014) 094 [arXiv:1312.6520] [INSPIRE]. experiments with GLoBES (General Long Baseline Experiment Simulator), Comput. Phys. of neutrino oscillation experiments with GLoBES 3.0: General Long Baseline Experiment 154 [arXiv:1109.6526] [INSPIRE]. status of leptonic CP-violation, JHEP 11 (2014) 052 [arXiv:1409.5439] [INSPIRE]. [1] D.V. Forero , M. Tortola and J.W.F. Valle , Global status o (...truncated)


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C. R. Das, Jukka Maalampi, João Pulido, Sampsa Vihonen. Determination of the θ 23 octant in LBNO, Journal of High Energy Physics, 2015, pp. 48, Volume 2015, Issue 2, DOI: 10.1007/JHEP02(2015)048