Cosmic Colliders in Binary Blazars Probing Ultra-High-Energy Particle Physics

While terrestrial colliders and fixed-target cosmic-ray interactions are bounded at center-of-mass (CM) energies $\sqrt{s}\lesssim \mathcal{O}({10}^5)\text{GeV}$, we demonstrate that bound sub-parsec binary blazars form broad-band, beam-beam hadronic ``Cosmic Colliders’', overcoming such limitation. Driven by modest jet misalignments (${\theta }_{\mathrm{m}\mathrm{i}\mathrm{s}}\sim 1^{\circ }-6^{\circ }$), co-streaming proton beams collide at CM energies reaching $\sqrt{s}\sim {10}^{10}\text{GeV}$ - six orders of magnitude above the Large Hadron Collider. Operating in a strictly optically thin regime (${\tau }_{pp}\ll 1$), the system performs a continuous CM energy scan, probing asymptotic QCD scaling, gluon saturation, and Froissart unitarity, while opening a possible high-sensitivity window into physics beyond the Standard Model. Secondary PeV-EeV neutrinos and sub-TeV $\gamma$-rays fall directly within reach of current and planned observatories such as LHAASO, CTAO, IceCube, and GRAND, establishing binary blazars as laboratories for physics at the ultimate energy limit.