Symanzik improvement of lattice QCD with four flavors of Wilson quarks

The running coupling of QCD with four flavors

“…In this paper, we want to calculate the step scaling function and the running coupling with four flavors of O(a) improved Wilson quarks. For the present work, the improvement coefficient c sw which is essential for the O(a) improvement with Wilson quarks was determined in a preceding paper [17]. We exploit this result in the simulations that we report in the following.…”

“…The definition of the correlation functions f A , f P is found e.g. in [17,27]. The second reference also contains a discussion of the influence of choosing the massless point in a way which differs from (5.8) at finite lattice spacing.…”

“…The choice of the improvement coefficients c t ,c t and c sw were as discussed in our preceding paper [17]. The range of β for our simulations was limited by the validity range of c sw with four flavors (β ≤ 5.0) [17].…”

Running of the Schroedinger functional coupling with four massless flavours

“…In the Schrödinger functional, Dirichlet boundary conditions are imposed in Euclidean time and therefore the O(a) Symanzik improvement of the theory requires boundary terms. Their coefficients are taken from perturbation theory, exactly as in [23], where we determined the crucial bulk O(a) improvement coefficient c sw non-perturbatively.…”

Determination of $c_{\rm sw}$ in $N_f=3+1$ Lattice QCD with massive Wilson fermions

“…The function c sw (g 2 0 ) has been determined for various numbers of massless, dynamical quark flavours and different actions [4,5,6,7,8,9,10]. It has found successful application in simulations with massless quarks (e.g.…”