Impact of scalar NSI on the neutrino mass ordering sensitivity at DUNE, HK and KNO

A bstract The study of neutrino non-standard interactions (NSI) is a well-motivated phenomenological scenario to explore new physics beyond the Standard Model. The possible scalar coupling of neutrinos ( ν ) with matter is one of such new physics scenarios that appears as a sub-dominant effect that can impact the ν -oscillations in matter. The presence of scalar NSI introduces an additional contribution directly to the ν -mass matrix in the interaction Hamiltonian and subsequently to the ν -oscillations. This indicates that scalar NSI may have a significant impact on measurements related to ν -oscillations e.g. leptonic CP phase ( δ CP ), θ 23 octant and neutrino mass ordering (MO). The linear scaling of the effects of scalar NSI with matter density also motivates its exploration in long-baseline (LBL) experiments. In this paper, we study the impact of a scalar-mediated NSI on the MO sensitivity of DUNE, HK and HK+KNO, which are upcoming LBL experiments. We study the impact on MO sensitivities at these experiments assuming that scalar NSI parameters are present in nature and is known from other non-LBL experiments. We observe that the presence of diagonal scalar NSI elements can significantly affect the ν -mass ordering sensitivities. We then also combine the data from DUNE with HK and HK+KNO to explore possible synergy among these experiments in a wider parameter space. We also observe a significant enhancement in the MO sensitivities for the combined analysis.