Is strong CP due to a massless up quark?

Preprint

18 December 2001

preprint
Published by arXiv in arXiv

Abstract

A standing mystery in the Standard Model is the unnatural smallness of the strong CP violating phase, theta_bar \le 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, 2 alpha_8 - alpha_5, are presented. We find 2 alpha_8 - alpha_5 = 0.115 \pm 0.051^stat \pm 0.25^syst, which is well outside the range allowing a massless up quark.

Keywords

CHIRAL LAGRANGIAN
MASSLESS UP QUARK
STANDARD MODEL
CP VIOLATING
STRONG CP
CP DUE
QUARK

All Related Versions

Version 1, 2001-12-18, ArXiv
Version 2, 2002-05-16, ArXiv
Version 3, 2002-08-26, ArXiv
Published version: Physical Review Letters, 90 (2), 021601.

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