The strength of the interactions in quantum chromodynamics (QCD), determined by the strong coupling, is predicted to decrease with energy leading to an asymptotic freedom. The ATLAS collaboration has measured how this parameter runs with energy in the TeV region with an unprecedented precision. The measurement, led by UAM-CIAFF researchers, has employed energy-energy correlators that characterize the geometrical distribution of the outgoing hadrons from particle collisions. This observable was measured in several regions of the phase space and was obtained by computing the angular difference between all the possible pairs of final-state particles, weighted by the product of the normalized energies of the two particles involved.  The impressive precision of these results has been achieved thanks to the availability of the next-to-next-to leading order calculations in perturbative QCD for three-jet configurations.

The article was published in JHEP, and was featured in the CERN courier.