Reassessing the sensitivity to leptonic CP violation

  • Mattias Blennow
  • Pilar Coloma
  • Enrique Fernandez-Martinez
Open Access
Regular Article - Theoretical Physics


We address the validity of the usual procedure to determine the sensitivity of neutrino oscillation experiments to CP violation. An explicit calibration of the test statistic is performed through Monte Carlo simulations for several experimental setups. We find that significant deviations from a χ 2 distribution with one degree of freedom occur for experimental setups with low sensitivity to δ. In particular, when the allowed region to which δ is constrained at a given confidence level is comparable to the whole allowed range, the cyclic nature of the variable manifests and the premises of Wilk’s theorem are violated. This leads to values of the test statistic significantly lower than a χ 2 distribution at that confidence level. On the other hand, for facilities which can place better constraints on δ the cyclic nature of the variable is hidden and, as the potential of the facility improves, the values of the test statistics first become slightly higher than and then approach asymptotically a χ 2 distribution. The role of sign degeneracies is also discussed.


Neutrino Physics CP violation Statistical Methods 


Open Access

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Copyright information

© The Author(s) 2015

Authors and Affiliations

  • Mattias Blennow
    • 1
  • Pilar Coloma
    • 2
  • Enrique Fernandez-Martinez
    • 3
    • 4
  1. 1.Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of TechnologyAlbaNova University CenterStockholmSweden
  2. 2.Center for Neutrino Physics, Physics DepartmentVirginia TechBlacksburgU.S.A.
  3. 3.Departamento de Física TeóricaUniversidad Autónoma de MadridMadridSpain
  4. 4.Instituto de Fíısica Teórica UAM/CSICMadridSpain

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