The experimental observation of the phenomena of neutrino oscillations was the first clear hint of physics beyond the Standard Model. The Standard Model needs an extension to incorporate the neutrino masses and mixing often called as beyond Standard Model. The models describing beyond Standard Model physics usually comes with some additional unknown couplings of neutrinos termed as non-standard interactions. The idea of non-standard interaction was initially proposed by Wolfenstein, where he explored how non-standard coupling of neutrinos with a vector field can give rise to matter effect in neutrino oscillations. Furthermore, there is also an intriguing prospect of neutrinos coupling with a scalar field, called scalar non-standard interaction. The effect of this type of scalar non-standard interaction appears as a medium dependent correction to the neutrino masses, instead of appearing as a matter potential. Hence scalar non-standard interaction may offer unique phenomenology in neutrino oscillations.
In this work, we have performed a synergy study of the effects of scalar non-standard interaction at various proposed long baseline experiments, viz. DUNE, T2HK and T2HKK. As the effect of scalar non-standard interaction scales linearly with environmental matter density, it can experience the matter density variations which makes long baseline experiments one of the suitable candidate to probe its effects. We found that the effect of scalar non-standard interaction on the oscillation probabilities of long baseline experiments is notable. In addition, scalar non-standard interaction can significantly effect the CP violation sensitivities as well as $\theta_{23}$ octant sensitivities of these long baseline experiments. Finally, we have also performed a combined sensitivity of these experiments towards constraining these scalar non-standard interaction parameters.