Scalar NSI: a unique tool for constraining absolute neutrino masses via neutrino oscillations

Abstract In the standard interaction scenario, a direct measurement of absolute neutrino masses via neutrino oscillations is not feasible, as the oscillations depend only on the mass-squared differences. However,scalar non-standard interactions (SNSI) can introduce sub-dominant terms in the neutrino oscillation Hamiltonian that can directly affect the neutrino mass matrix, thereby making SNSI a unique tool for neutrino mass measurements. In this work, for the first time, we constrain the absolute masses of neutrinos by probing SNSI in a neutrino oscillation experiment. We show that a bound on the neutrino mass can be induced in the presence of SNSI at DUNE. We note that the constraints on the neutrino mass are much better for $$\eta _{\mu \mu }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>η</mml:mi> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi>μ</mml:mi> </mml:mrow> </mml:msub> </mml:math> and $$\eta _{\tau \tau }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>η</mml:mi> <mml:mrow> <mml:mi>τ</mml:mi> <mml:mi>τ</mml:mi> </mml:mrow> </mml:msub> </mml:math> as compared to $$\eta _{ee}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>η</mml:mi> <mml:mrow> <mml:mi>ee</mml:mi> </mml:mrow> </mml:msub> </mml:math> for both NO and IO scenarios. We have also explored the constraints on the neutrino mass for different choices of $$\delta _{CP}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>δ</mml:mi> <mml:mrow> <mml:mi>CP</mml:mi> </mml:mrow> </mml:msub> </mml:math> and $$\theta _{23}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>θ</mml:mi> <mml:mn>23</mml:mn> </mml:msub> </mml:math> for both neutrino mass orderings. This study shows that SNSI can serve as an interesting avenue to constrain the absolute neutrino masses in long-baseline neutrino experiments via neutrino oscillations.