Exploring invisible neutrino decay at ESSnuSB

Sandhya Choubey,Daniel Kempe,Monojit Ghosh,Tommy Ohlsson

doi:10.1007/jhep05(2021)133

Abstract

We explore invisible neutrino decay in which a heavy active neutrino state decays into a light sterile neutrino state and present a comparative analysis of two baseline options, 540 km and 360 km, for the ESSnuSB experimental setup. Our analysis shows that ESSnuSB can put a bound on the decay parameter τ3/m3 = 2.64 (1.68) × 10−11 s/eV for the baseline option of 360 (540) km at 3σ. The expected bound obtained for 360 km is slightly better than the corresponding one of DUNE for a charged current (CC) analysis. Furthermore, we show that the capability of ESSnuSB to discover decay, and to measure the decay parameter precisely, is better for the baseline option of 540 km than that of 360 km. Regarding effects of decay in δCP measurements, we find that in general the CP violation discovery potential is better in the presence of decay. The change in CP precision is significant if one assumes decay in data but no decay in theory.

Highlights

JHEP05(2021)133 for neutrino propagation is modified, and one can measure the decay parameter as well as the effect of decay on the measurement of the standard oscillation parameters in a neutrino oscillation experiment
We have considered two baseline options of ESSnuSB, which are 540 km and 360 km, respectively, and studied (i) the capability to put bounds on the decay parameter, (ii) the capability to discover invisible decay, (iii) the bounds on the decay parameter obtained with other experiments, (iv) the potential to measure a particular value of decay parameter, and (v) the effect of decay on the measurement of δCP
We have shown that the capability of ESSnuSB to put bounds on the decay parameter or the sensitivity χ2 is better for the baseline option of 360 km, while its capability to discover decay with a particular value of decay parameter or the discovery χ2 is better for the baseline option of 540 km

Summary

Introduction

JHEP05(2021)133 for neutrino propagation is modified, and one can measure the decay parameter as well as the effect of decay on the measurement of the standard oscillation parameters in a neutrino oscillation experiment. Decay due to ν3 can be measured in present and future accelerator, atmospheric, and reactor neutrino experiments. Studies of invisible decay in the accelerator neutrino experiments T2K [9], NOνA [10], MINOS [11], DUNE [12], and MOMENT [13] can be found in refs. [21,22,23], for the study with atmospheric neutrino data of the future ultra-high energy neutrino experiment KM3NeT-ORCA [24], see ref. We study the scenario of invisible decay of the neutrino state ν3 in the future long-baseline experiment ESSnuSB [28, 29]. We consider both baseline options to estimate the sensitivity to invisible neutrino decay at ESSnuSB.

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Methods

Conclusion