Uncharted Logarithmic Structures in QCD Transverse-Energy Flow

We investigate the QCD transverse-energy (E_{T}) flow distribution within an azimuthal region of phase space, defined by an angular interval Δϕ on the plane transverse to a chosen reference axis. Vetoes on the resulting E_{T} are widely employed at the LHC to isolate missing transverse momentum in final states with invisible particles. We show that this observable has logarithmic structures never seen before in QCD calculations. Notably, its description involves the resummation of nonglobal and coherence-violating logarithmic contributions that are more singular than any reported to date. We analyze its all-orders behavior, providing analytical resummation for pp collisions at next-to-double-logarithmic accuracy and numerical resummation at leading-logarithmic accuracy in the Veneziano limit. We further present a computation of the leading coherence-violating correction, highlighting its novel structure. The intricate structure of vetoes in azimuthal gaps reveals new aspects of QCD dynamics and offers a novel probe of coherence-violating logarithmic terms in LHC observables.