Is the up-quark massless?

Irving, AC, McNeile, C, Michael, C, Sharkey, KJ ORCID: 0000-0002-7210-9246 and Wittig, H (2001) Is the up-quark massless? Physics Letters B, 518 (3-4). pp. 243-251.

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Abstract

We report on determinations of the low-energy constants alpha5 and alpha8 in the effective chiral Lagrangian at O(p^4), using lattice simulations with N_f=2 flavours of dynamical quarks. Precise knowledge of these constants is required to test the hypothesis whether or not the up-quark is massless. Our results are obtained by studying the quark mass dependence of suitably defined ratios of pseudoscalar meson masses and matrix elements. Although comparisons with an earlier study in the quenched approximation reveal small qualitative differences in the quark mass behaviour, numerical estimates for alpha5 and alpha8 show only a weak dependence on the number of dynamical quark flavours. Our results disfavour the possibility of a massless up-quark, provided that the quark mass dependence in the physical three-flavour case is not fundamentally different from the two-flavour case studied here.

Item Type:	Article
Additional Information:	## TULIP Type: Articles/Papers (Journal) ## official_url: <Go to ISI>://000171529400004
Uncontrolled Keywords:	CHIRAL PERTURBATION-THEORY, ONE-LOOP ORDER, LATTICE QCD, O(A) IMPROVEMENT, QUENCHED QCD, LIGHT QUARKS, LOGARITHMS, SYMMETRY, RATIOS
Subjects:	?? QC ??
Divisions:	Faculty of Science and Engineering > School of Physical Sciences > Mathematical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	20 Aug 2008 08:37
Last Modified:	16 Dec 2022 09:17
DOI:	10.1016/s0370-2693(01)01062-0
Related URLs:	Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/569