The running of the coupling in SU(N) pure gauge theories

by Mr Gregory Moraitis (Swansea University)

Friday 30 May 2008, 11:00 → 12:00 Europe/Zurich

Room A (CERN)

The running of the coupling is studied in SU(4) gauge theory using the Schroedinger functional technique. Up to energies of the order of the square root of the string tension, the running is found to agree with the two-loop perturbative formula. Relating the perturbative to the non-perturbative regime of the running and converting to the MS-bar scheme allows one to extract the ratio Lambda/sqrt(sigma). The result is then used in combination with similar results present in the literature for SU(2) and SU(3) to extract Lambda/sqrt(sigma) in the large N limit. With the assumption that O(1/N^2) terms correctly describe the data from N=2 onwards, our best fit parameterisation for the ratio Lambda/sqrt(sigma) is 0.528(40) + 0.18(36)/N^2. Our results agree with a recent study of the same quantity performed using the Parisi mean field scheme as an intermediate scheme.