The conclusions of the Physics Working Group of the International Scoping Study of a future Neutrino Factory and super-beam facility (the ISS) are presented. The ISS was carried out by the international community between NuFact05, (the 7th International Workshop on Neutrino Factories and Super-beams, Laboratori Nazionali di Frascati, Rome, 21-26 June 2005) and NuFact06 (Ivine, CA, 24-30 August 2006). The physics case for an extensive experimental programme to understand the properties of the neutrino is presented and the role of high-precision measurements of neutrino oscillations within this programme is discussed in detail. The performance of second-generation super-beam experiments, beta-beam facilities and the Neutrino Factory are evaluated and a quantitative comparison of the discovery potential of the three classes of facility is presented. High-precision studies of the properties of the muon are complementary to the study of neutrino oscillations. The Neutrino Factory has the potential to provide extremely intense muon beams and the physics potential of such beams is discussed in the final section of the report.

We explore the combined physics potential of T2K and NOνA in light of the moderately large measured value of θ 13 . For sin 2 2θ 13 = 0.1, which is close to the best fit value, a 90% C.L. evidence for the hierarchy can be obtained only for the combinations (Normal hierarchy, −170 • ≤ δ CP ≤ 0 • ) and (Inverted hierarchy, 0 • ≤ δ CP ≤ 170 • ), with the currently planned runs of NOνA and T2K. However, the hierarchy can essentially be determined for any value of δ CP , if the statistics of NOνA are increased by 50% and those of T2K are doubled. Such an increase will also give an allowed region of δ CP around its true value, except for the CP conserving cases δ CP = 0 or ± 180 • .

Recent measurement of a moderately large value of θ 13 is very good news for both current and future long-baseline experiments. It enables them to address the outstanding issues in neutrino oscillation physics: (a) Neutrino mass hierarchy, (b) Octant of θ 23 and (c) CP violation. The current experiments, T2K and NOνA, can only give 90% C.L. hint of hierarchy and 95% hint of octant. Future facilities are imperative for making measurements at 3σ level or better. We compare the physics reach of two future superbeam facilities, LBNE and LBNO in their first phases of run, to resolve the above issues. LBNO, by itself, can determine the hierarchy at more than 10σ , even for the lowest allowed value of sin 2 θ 23 (true) = 0.34. For LBNE, the hierarchy reach is more modest. In particular, LBNE, by itself, will not be able to reach 3σ hierarchy determination, for the most unfavourable values of δ CP. The sensitivities of these future facilities improve significantly with the addition of the projected data from T2K and NOνA. Thus, LBNE is able to achieve better than 3σ hierarchy determination in combination with T2K and NOνA. The addition of T2K and NOνA data also leads to (a) significant boost in the CP violation discovery and (b) a 3σ octant resolution for sin 2 θ 23 (true) ≤ 0.44 or for sin 2 θ 23 (true) ≥ 0.58 for all values of δ CP (true) for both LBNE and LBNO.

We have identified some important and worthwhile physics opportunitites with a possible neutrino detector located in India. Particular emphasis is placed on the geographical advantage with a stress on the complimentary aspects with respect to other neutrino detectors already in operation.Comment: 9 pages; arXiv copy of published proceedings contributio

Preliminary results of MINOS experiment indicate that θ 23 is not maximal. Global fits to world neutrino data suggest two nearly degenerate solutions for θ 23 : one in the lower octant (LO: θ 23 < 45 • ) and the other in the higher octant (HO: θ 23 > 45 • ). ν µ → ν e oscillations in superbeam experiments are sensitive to the octant and are capable of resolving this degeneracy. We study the prospects of this resolution by the current T2K and upcoming NOνA experiments. Because of the hierarchy-δ CP degeneracy and the octant-δ CP degeneracy, the impact of hierarchy on octant resolution has to be taken into account. As in the case of hierarchy determination, there exist favorable (unfavorable) values of δ CP for which octant resolution is easy (challenging). However, for octant resolution the unfavorable δ CP values of the neutrino data are favorable for the antineutrino data and vice-verse. This is in contrast to the case of hierarchy determination. In this work, we compute the combined sensitivity of T2K and NOνA to resolve the octant ambiguity. If sin 2 θ 23 = 0.41, then NOνA can rule out all the values of θ 23 in HO at 2σ C.L., irrespective of the hierarchy and δ CP . We show that a balanced neutrino-anti-neutrino run of T2K is better for octant resolution compared to pure neutrino run.