Nelson Daniel R, Fleming George T, Kilcup Gregory W
Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
Phys Rev Lett. 2003 Jan 17;90(2):021601. doi: 10.1103/PhysRevLett.90.021601. Epub 2003 Jan 15.
A standing mystery in the standard model is the unnatural smallness of the strong CP violating phase. A massless up quark has long been proposed as one potential solution. A lattice calculation of the constants of the chiral Lagrangian essential for the determination of the up quark mass, 2alpha(8)-alpha(5), is presented. We find 2alpha(8)-alpha(5)=0.29+/-0.18, which corresponds to m(u)/m(d)=0.410+/-0.036. This is the first such calculation using a physical number of dynamical light quarks, N(f)=3.
