Updated Results for the Search for $\bar{\nu}_{\mu} \rightarrow \bar{\nu}_{e}$ Oscillations from T2K in the 3-flavour Framework

I report the results of a search for $\bar{\nu}{\mu} \rightarrow \bar{\nu}{e}oscillationsattheT2Kexperimentina3−flavourframeworkusinganexposureof oscillations at the T2K experiment in a 3-flavour framework using an exposure of 1.49 \times 10^{21}ProtonsOnTarget(POT)in Protons On Target (POT) in \numodeand mode and 1.12 \times 10^{21}POTin POT in \bar{\nu}mode,anincreaseof mode, an increase of 50\%inthe in the \bar{\nu}$ exposure compared to results reported in 2016.

Results are reported for a joint analysis where candidate events are selected from the e-like events observed in ν¯ \bar{\nu} running mode, while four other far detector event samples are used with near-detector data to constrain the values of the oscillation and systematic parameters, including the mass-hierarchy, giving the best possible constraint on $\bar{\nu}{e}appearance.Twohypothesesaretested,a)no appearance. Two hypotheses are tested, a) no \bar{\nu}{e}appearanceandb) appearance and b) \bar{\nu}_{e}$ appearance according to the current best knowledge of the PMNS matrix, where both rate-only and rate+shape analyses are performed, producing p-values for each hypothesis.