RT Journal Article T1 Measuring the QCD Gell-Mann–Low ψ function A1 Brodsky, S. J. A1 Merino, C. A1 Peláez Sagredo, José Ramón AB We present a general method for extracting the Gell-Mann-Low logarithmic derivative of an effective charge of an observable directly from data as a mean for empirically verifying the universal terms of the QCD beta function. Our method avoids the biases implicit in fitting to QCD-motivated forms as well as the interpolation errors introduced by constructing derivatives from discrete data. We also derive relations between moments of effective charges as new tests of perturbative QCD. [S0556-2821(99)00221-0]. PB Amer Physical Soc SN 0556-2821 YR 1999 FD 1999-11-01 LK https://hdl.handle.net/20.500.14352/59878 UL https://hdl.handle.net/20.500.14352/59878 LA eng NO ©1999 The American Physical Society.C.M. and J.R.P. thank the Theory Group at SLAC for their kind hospitality. J.R.P. acknowledges the Spanish Ministerio de Educación y Cultura for financial support, as well as the Departamento de Física de Partículas of the Universidade de Santiago de Compostela for its hospitality. We also thank M. Melles, J. Rathsman and N. Toumbas for helpful conversations. This research was partially supported by the Department of Energy under contract DE-AC03-76SF00515 and the Spanish CICYT under contracts AEN-96-1673, AEN97-1693. NO Spanish Ministerio de Educación y Cultura NO E.U. Department of Energy NO Spanish CICYT DS Docta Complutense RD 24 abr 2025