Ambiguities in the up quark mass
Abstract
Description
It has long been known that no physical singularity is encountered as up quark mass is adjusted from small positive to negative values as long as all other quarks remain massive. This is tied to an additive ambiguity in the definition of the quark mass. This calls into question the acceptability of attempts to solve the strong CP problem via a vanishing mass for the lightest quark.
9 pages, 1 figure. Revision as will appear in Physical Review Letters. Simplified renormalization group discussion and title change requested by PRL
9 pages, 1 figure. Revision as will appear in Physical Review Letters. Simplified renormalization group discussion and title change requested by PRL