A lattice computation of the first moment of the kaon's distribution amplitude

• Published in: Physics letters. B Vol. 641; no. 1; pp. 67 - 74
• Main Authors: Boyle, P.A., Donnellan, M.A., Flynn, J.M., Jüttner, A., Noaki, J., Sachrajda, C.T., Tweedie, R.J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 28.09.2006; Elsevier Science
• Subjects: Exact sciences and technology; Nuclear physics; Physics; The physics of elementary particles and fields; 11.15.Ha; 12.38.Gc; 12.39.St; 11.30.Hv; 14.40.-n; Kaons; Operator; Uncertainty; Fermions; SU theory; Domain walls; Amplitude distribution; Renormalization; Flavor
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2006.07.033

We present a lattice computation of the first moment of the kaon's leading-twist distribution amplitude. The results were computed using ensembles with 2+1 dynamical flavours with the domain wall fermion action and Iwasaki gauge action from the RBC and UKQCD joint dataset. The first moment is non-zero because of SU(3)-breaking effects, and we find that we are able to measure these effects very clearly. We observe the expected chiral behaviour and finally obtain 〈ξ〉(2 GeV)≡3/5aK1(2 GeV)=0.032(3), which agrees very well with results obtained using sum-rules, but with a significantly smaller error. We discuss the systematic uncertainties in detail and explain the prospects for their further reduction. In particular, we are implementing a programme of non-perturbative renormalization to improve the precision on the normalization of the lattice operators (currently performed perturbatively) and are repeating the calculation on a large lattice (243×64 as compared to the present 163×32 lattice).