HEP/Astro Journal Club -- Friday, 11 January 2002

Is strong CP due to a massless up quark?

Daniel Nelson (OSU)

Abstract

A standing mystery in the Standard Model is the unnatural smallness of the strong CP violating phase, θ ≤ 10^-9. The possibility of a massless up quark has long been proposed as a potential solution. Several lattice calculations of a combination of the low energy constants of the chiral Lagrangian essential for the determination of the up quark mass, 2α₈ − α₅, are presented. We find 2α₈ − α₅ = 0.115 ± 0.051^stat ± 0.25^syst, which is well outside the range allowing a massless up quark.

References

D. R. Nelson, G. T. Fleming and G. W. Kilcup, Is strong CP due to a massless up quark? hep-lat/0112029, submitted to Phys. Rev. Lett.

12:30, Smith Lab 4079