Determining the strange quark mass for 2-flavour QCD

Using the O(a) Symanzik improved action an estimate is given for the strange quark mass for unquenched (n_f=2) QCD. The determination is via the axial Ward identity (AWI) and includes a non-perturbative evaluation of the renormalisation constant. Numerical results have been obtained at several lattice spacings, enabling the continuum limit to be taken. Our results indicate a value for the strange quark mass (in the MS-bar scheme at a scale of 2 GeV) in the range 100 - 130 MeV. A comparison is also made with other recent lattice determinations of the strange quark mass using dynamical sea quarks.