Charged black holes in KR gravity: Weak deflection angle, shadow cast, quasinormal modes and neutrino annihilation

Abstract

In this paper, we investigate the phenomenology of electrically charged black holes in a Lorentz-violating gravitational framework mediated by a background Kalb-Ramond (KR) antisymmetric tensor field. Employing the Gauss-Bonnet theorem (GBT) in a non-asymptotically flat geometry, we derive analytic expressions for the weak deflection angle of light and massive particles, revealing persistent corrections due to the Lorentz-violating parameter 8. Scalar and Dirac perturbations are also studied using both the Wentzel-Kramers-Brillouin (WKB) approximation and the P & ouml;schl-Teller approximation approach to verify the stability of the solution against these types of perturbations. Shadow analysis further uncovers a nontrivial deformation of the photon sphere and critical impact parameter, with KR-induced effects modifying the charge contribution in a manner incompatible with standard Einstein-Maxwell theory. Constraints derived from the Event Horizon Telescope (EHT) data for Sgr A* and M87* validate the model and provide stringent bounds on 8, establishing the KR framework as an observationally testable extension of General Relativity (GR).