Flavour symmetry breaking in the kaon parton distribution amplitude

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dc.contributor.authorShi, C.
dc.contributor.authorChang, L.
dc.contributor.authorRoberts, C.
dc.contributor.authorSchmidt, S.
dc.contributor.authorTandy, P.
dc.contributor.authorZong, H.
dc.date.issued2014
dc.description.abstractWe compute the kaon’s valence-quark (twist-two parton) distribution amplitude (PDA) by projecting its Poincaré-covariant Bethe–Salpeter wave-function onto the light-front. At a scale ζ = 2GeV, the PDA is abroad, concave and asymmetric function, whose peak is shifted 12–16% away from its position in QCD’s conformal limit. These features are a clear expression of SU(3)-flavour-symmetry breaking. They show that the heavier quark in the kaon carries more of the bound-state’s momentum than the lighter quark and also that emergent phenomena in QCD modulate the magnitude of flavour-symmetry breaking: it is markedly smaller than one might expect based on the difference between light-quark current masses. Our results add to a body of evidence which indicates that at any energy scale accessible with existing or foreseeable facilities, a reliable guide to the interpretation of experiment requires the use of such nonperturbatively broadened PDAs in leading-order, leading-twist formulae for hard exclusive processes instead of the asymptotic PDA associated with QCD’s conformal limit. We illustrate this via the ratio of kaon and pion electromagnetic form factors: using our nonperturbative PDAs in the appropriate formulae, Fk/Fπ=1.23 at spacelike-Q2=17 GeV2, which compares satisfactorily with the value of 0.92(5) inferred in e+e− annihilation at s=17 GeV2.
dc.description.statementofresponsibilityChao Shi, Lei Chang, Craig D. Roberts, Sebastian M. Schmidt, Peter C. Tandy, Hong-shi Zong
dc.identifier.citationPhysics Letters B: Nuclear Physics and Particle Physics, 2014; 738:512-518
dc.identifier.doi10.1016/j.physletb.2014.07.057
dc.identifier.issn0370-2693
dc.identifier.issn0370-2693
dc.identifier.urihttp://hdl.handle.net/2440/100416
dc.language.isoen
dc.publisherElsevier
dc.relation.granthttp://purl.org/au-research/grants/arc/FL0992247
dc.rights© 2014 Argonne National Laboratory and the authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/ . Funded by SCOAP3.
dc.source.urihttps://doi.org/10.1016/j.physletb.2014.07.057
dc.subjectdynamical chiral symmetry breaking; Dyson–Schwinger equations; factorisation in heavy-meson decays; flavour symmetry breaking; light pseudoscalar mesons; parton distribution amplitudes; strange quarks
dc.titleFlavour symmetry breaking in the kaon parton distribution amplitude
dc.typeJournal article
pubs.publication-statusPublished

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