Dark Matter Pair Production in Blazar Jets from TeV to 10⁸ GeV: Kinematically Allowed but Unobservable

We examine whether proton-proton collisions inside blazar jets can produce dark matter. Standard leptohadronic and hadronic blazar models take the accelerated protons to be isotropic in the rest frame of the emitting region, so collisions occur at all angles and reach center-of-mass energies well above those of the LHC. We describe the production of a Dirac-fermion dark-matter particle X with the dimension-6 contact operator (1/Λ²)(q̄q)(X̄X). At a benchmark collision energy of 3.16×10⁸ GeV, the parameter space that lies above threshold and within the validity of the effective theory is 3.16×10⁸ < Λ ≤ 10¹¹ GeV and 10⁶ ≤ m_X < 1.58×10⁸ GeV. Even if X decayed promptly into visible particles, the resulting fluxes would remain at least 2.6, 16.3 and 23.7 orders of magnitude below the Pierre Auger, IceCube and Fermi-LAT limits we adopt. We then use published proton spectra of TXS 0506+056 and BL Lacertae, with the largest coupling allowed by EFT validity and direct-detection bounds, to compute production rates for m_X = 10³–10⁸ GeV and the flux of stable X at Earth. The expected event rate in a cubic-kilometer detector is at least 26 orders of magnitude too small at every mass. Dark-matter production in blazar jets is kinematically allowed but unobservable. Code and data: https://github.com/kirtii56/dark-matter-blazar-jets