Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 93: Neutrino physics without accelerators IV

T 93.7: Talk

Thursday, March 18, 2021, 17:30–17:45, Tr

Likelihood-based searches of sterile neutrino signals in Double Chooz. — •Lars Heuermann, Markus Bachlechner, Philipp Soldin, Achim Stahl, and Christopher Wiebusch — RWTH Aachen University - Physics Institute III B, Aachen, Germany

Double Chooz is a reactor neutrino disappearance experiment with the main goal to measure the neutrino oscillation. The setup consists of two identical detectors at baselines of 1050 m and 400 m, optimized for the neutrino mixing angle θ₁₃. Additional, hypothetical sterile neutrino flavours, which do not participate in weak interactions, still might contribute to anti-electron-neutrino disappearance and thus could be measurable in Double Chooz. In this search, we test the data in a maximum likelihood analysis with respect to the parameters of a model with one additional sterile neutrino flavour (3+1 model). A particular challenge is that Wilks’ theorem is not fulfilled and the parameter scan is computationally expensive. An initial analysis has been performed with a subset of the data. Here we extend the analysis to the full available data set. We will present the analysis method, study of systematic uncertainties and conclude with upper exclusion boundaries for the sterile mixing parameters Δ m₄₁² and sin²(2θ₁₄) through likelihood based scans.