NUFACT11 Round Table Discussion — Questions & Answers

Abstract

This presents the response to questions formulated by a round table discussion panel to the NUFACT11 participants. The main points made were as follows.Neutrino mass is physics beyond the Standard Model; it presents a very deep puzzle to solve, with the answers to several fundamental questions as potential reward. Precision measurement of oscillation parameters is one essential way to access information needed to solve this puzzle and there is a relatively clear (but not easy) way forward. Large θ13 makes the appearance signals larger, but does not allow to relax the requirements on high beam intensity and large detector masses; it creates a difficult challenge on systematic errors, which will require dedicated ancillary experiments. Of particular interest is a low intensity muon storage ring for required cross-section measurements.There exist already extended bottom-up international collaboration in both physics and R&D experiments. All three main regions have plans for upgraded super-beams and associated detectors, with a variety of (mostly) complementary baselines, proceeding in an incremental way. The ultimate precision and verification of the neutrino mixing picture requires new types of neutrino beams based on storage rings. For low energy neutrinos, the beta-beam is a possible (but substantial) intermediate step. The Neutrino Factory offers the best precision and best sensitivity to deviations from the standard picture. Coordinated international R&D is pursued. International collaboration at the top level would be beneficial in acknowledging the process, so as make sure that intermediate steps are effectively building up in complementary fashion towards the ultimate goals.