Scalar NSI: A unique tool for constraining absolute neutrino masses via $\nu$-oscillations

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. We have explored the constraints on the lightest neutrino mass with different choices of $\delta_{CP}$ and $\theta_{23}$ for both neutrino mass hierarchies. We show that a bound on the neutrino mass can be induced in the presence of SNSI at DUNE. We find that the lightest neutrino mass can be constrained with $\eta_{\tau\tau}$ for normal mass hierarchy irrespective of the octant of $\theta_{23}$ and the value of the CP phase $\delta_{CP}$. This study suggests that SNSI can serve as an interesting avenue to constrain the absolute neutrino masses in long-baseline neutrino experiments via neutrino oscillations.