The leptonic CP phase from T2(H)K and μ + decay at rest

Abstract

Combining ν oscillations at T2K or T2HK with ν oscillations from µ + decay at rest (DAR) allows a determination of the leptonic CP-violating phase δ. The degeneracies of this phase with θ 13 and θ 23 are broken and δ can be reliably distinguished from 180 • − δ. We present the sensitivity to δ of T2(H)K together with a µ + DAR experiment using Super-K as a near detector and Hyper-K at the Tochibora site as a far detector.

A hybrid setup for fundamental unknowns in neutrino oscillations using T2HK (ν) and μ-DAR ν ¯ $$ \left(\overline{\nu}\right) $$

“…An elegant way of tackling this issue is to replace the antineutrino run of the superbeam experiment with the antineutrinos from muon decay at rest (µ-DAR) [43][44][45]. In a stopped pion source, the low energy protons of a few GeV energy are bombarded on a target to produce both π + and π − .…”

“…The physics reach of similar setups 5 to measure δ CP was presented in refs. [44,45]. In this work, we explore the physics reach of a setup, where we replace the antineutrino run of T2HK, with antineutrinos from muon decay at rest (µ-DAR).…”

“…[45]. A six year run of µ-DAR is considered which corresponds to a total integrated 1.1 × 10 25 pot.…”

“…We have incorporated these backgrounds in our analysis following ref. [45]. A neutrino oscillation experiment with a µ-DAR source has much lower systematic errors, since the flux of neutrinos is exactly known from kinematics and the IBD cross-section is well measured in the MeV range.…”

Neutrino physics with accelerator driven subcritical reactors

“…Such a setup has several advantages for measuring δ [20,21]. Not only is the ν e spectrum well known, but since they are detected via IBD the cross section is also well known and the capture of the resulting neutron provides a double coincidence which can be used for background rejection.…”