Speaker
Description
In this talk, I will discuss a class of non-global observables in which one vetoes transverse-energy flow inside an azimuthal interval $\Delta \phi$ defined with respect to a suitable reference axis. Such vetoes are widely used in measurements involving missing transverse momentum at the LHC and probe a kinematic regime that has not previously been explored. We show that these observables exhibit novel logarithmic structures. In particular, both non-global logarithms (NGLs) and coherence-violating logarithms (CVLs) acquire an additional power of the large logarithm $L$, making them more singular than in standard non-global observables. For $pp$ collisions, we study the all-orders structure of these logarithms and perform an analytical resummation at next-to-double-logarithmic (NDL) accuracy, together with a numerical leading-logarithmic (LL) resummation in the large-$N_c$ limit. Furthermore, we calculate the leading contribution of the CVLs and show that they are enhanced from N$^{3}$DL to NNDL accuracy. This enhanced sensitivity makes the observable a particularly promising probe of collinear-factorization breaking at hadron colliders.