The European Physical Journal C

, Volume 69, Issue 1–2, pp 159–167 | Cite as

Kπ form factors with reduced model dependence

  • The RBC-UKQCD Collaboration
  • P. A. Boyle
  • J. M. Flynn
  • A. JüttnerEmail author
  • C. Kelly
  • C. Maynard
  • H. Pedroso de Lima
  • C. T. Sachrajda
  • J. M. Zanotti
Regular Article - Theoretical Physics


Using partially twisted boundary conditions we compute the Kπ semi-leptonic form factors in the range of momentum transfers \(0\lesssim q^{2}\leq q^{2}_{\max}=(m_{K}-m_{\pi})^{2}\) in lattice QCD with N f =2+1 dynamical flavours. In this way we are able to determine \(f_{+}^{K\pi}(0)\) without any interpolation in the momentum transfer, thus eliminating one source of systematic error. This study confirms our earlier phenomenological ansatz for the strange quark mass dependence of the scalar form factor. We identify and estimate potentially significant NNLO effects in the chiral expansion that guides the extrapolation of the data to the physical point. Our main result is \(f_{+}^{K\pi}(0)=0.9599(34)(^{+31}_{-47})(14)\), where the first error is statistical, the second error is due to the uncertainties in the chiral extrapolation of the lattice data and the last error is an estimate of potential discretisation effects.


Form Factor Chiral Perturbation Theory Valence Quark Chiral Expansion Twist Boundary Condition 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag / Società Italiana di Fisica 2010

Authors and Affiliations

  • The RBC-UKQCD Collaboration
  • P. A. Boyle
    • 1
  • J. M. Flynn
    • 2
  • A. Jüttner
    • 3
    Email author
  • C. Kelly
    • 1
  • C. Maynard
    • 1
  • H. Pedroso de Lima
    • 2
  • C. T. Sachrajda
    • 2
  • J. M. Zanotti
    • 1
  1. 1.School of Physics and AstronomyUniversity of EdinburghEdinburghUK
  2. 2.School of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
  3. 3.Theory Group, Physics DepartmentCERNGeneva 23Switzerland

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