Speaker
Description
T2K is a long baseline accelerator neutrino experiment in Japan which studies
neutrino oscillations with a narrow-band muon neutrino beam peaked at 0.6 GeV.
The large water Cherenkov detector Super-Kamiokande (SK) located 295 km away
from the proton target acts as a far detector and provides high quality
samples for oscillation analysis. In the present study the T2K setup is used
to search for light sterile neutrinos.
Sterile neutrinos are hypothetical particles that do not interact via
weak interactions and couple with active neutrinos only through mixing. They
are present in many extensions of the Standard Model and can have any masses
from 0 to the GUT scale. Light sterile neutrinos of eV masses could modify the
standard 3-flavour oscillation pattern and explain anomalies observed in some
oscillation experiments.
A sterile neutrino analysis at T2K was developed to constrain
$\theta_{24}$ and $\theta_{34}$ mixing elements in the 3+1 sterile neutrino
model. This is the first study of sterile neutrinos at T2K which is based on
SK data. To enhance the sensitivity to the effects related to the presence of
sterile neutrinos, a joint analysis is done using both charged-current and the
newly implemented neutral-current (NC) oscillation samples (NC$\pi^0$ with 2
rings observed and NC gamma de-excitation) at the far detector. The primary
sensitivity for this sterile search comes from NC samples where we are looking
for a deficit due to the oscillations to the sterile neutrino.
The analysis strategy and the results obtained for the current T2K
data (2010-2017 data taking) are presented.
