Measurement of energy correlators inside jets and determination of the strong coupling constant

We measure the two-point and three-point energy correlator jet substructure observables (E2C and E3C), using LHC 13 TeV data collected by the CMS experiment. These measurements reveal in a straightforward way the two most important features of strong interactions, confinement and asymptotic freedom. The E2C and E3C distributions show a sharp transition from the falling scaling behavior characterizing the quantum interactions of quarks and gluons to an integer power law reflective of classical noninteracting hadrons. The ratio of E3C/E2C is directly proportional to the strong coupling constant $\alpha_S$. The slopes of the ratio of the distribution of E3C and E2C are measured in multiple jet transverse momentum regions, consistent with the expected decrease of $\alpha_S$ with increasing energy due to asymptotic freedom. Measurements of scaling behavior are compared to theoretical predictions with all-orders resummation at next-to-next-to-leading logarithmic accuracy matched to a fixed-order next-to-leading order calculation, yielding an $\alpha_S (m_Z)$ value of $0.1229^{+0.0040}_{-0.0050}$. This is the most precise extraction of $\alpha_S (m_Z)$ using jet substructure observables to date.