Computing Charged Anisotropic Compact Stars in f(Q,T) Gravity: Probing the Lower Mass Gap through Matter–Non-Metricity Coupling

The existence of compact objects in the lower mass-gap region poses a significant challenge to conventional descriptions of neutron stars based on general relativity and standard equations of state. In this work, we investigate whether the coupling between non-metricity and matter can provide an additional mechanism to sustain supermassive compact configurations. To this end, we study charged anisotropic stellar models within the framework of f(Q,T) gravity, considering the linear form f(Q,T)=α q Q+ β t T. By employing the extended gravitational decoupling approach and a charged Krori–Barua seed solution, we obtain an exact interior configuration smoothly matched to an exterior Reissner–Nordström spacetime. The resulting solutions satisfy all standard requirements of physical acceptability, including regularity, positivity of the thermodynamic variables, causality, energy conditions, hydrostatic equilibrium, and dynamical stability. We show that the matter–non-metricity coupling substantially increases the maximum supported mass, allowing stable stellar configurations to extend into the observational lower mass-gap region while remaining consistent with current pulsar and gravitational-wave measurements. Our results suggest that f(Q,T) gravity offers a viable geometric mechanism to alleviate the tension between observed massive compact objects and the limits predicted within general relativity.