Irving, A.C.; McNeile, C.; Michael, C.; Sharkey, K.J. and Wittig, H. (2001) Is the up-quark massless? Physics Letters B, 518 (3-4). pp. 243-251. ISSN 0370-2693
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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.
|Additional Information:||LTH 516. arXiv Number: arXiv:hep-lat/0107023v2. Available online 17 September 2001. Issue: 18 October 2001.|
|Uncontrolled Keywords:||CHIRAL PERTURBATION-THEORY; ONE-LOOP ORDER; LATTICE QCD; O(A) IMPROVEMENT; QUENCHED QCD; LIGHT QUARKS; LOGARITHMS; SYMMETRY; RATIOS|
|Subjects:||Q Science > QC Physics|
|Departments, Research Centres and Related Units:||Academic Faculties, Institutes and Research Centres > Faculty of Science > Department of Mathematical Sciences|
|Deposited On:||20 Aug 2008 09:37|
|Last Modified:||20 Mar 2012 11:24|
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