The Relation between the Perturbative QCD Scale Λs and Hadronic Masses from Light-Front Holography

QCD is well understood at short distances where perturbative calculations are feasible. Establishing an explicit analytic connection between the short-distance regime and the large-distance physics of quark confinement has been a long-sought goal. A major challenge is to relate the scale Λs underlying the evolution of the QCD coupling in the perturbative regime to the masses of hadrons. We show here how new theoretical insights into the behavior of QCD at large distances leads to such a relation. The resulting prediction for Λs in the MS¯ scheme agrees well with experimental measurements. Conversely, the relation can be used to predict the masses of hadrons composed of light quarks with the measured value of Λs as the sole parameter. We also use “light-front holography” to determine the analytic form of αs(Q2) at small Q2.