Diapositiva 1

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• OUTLINE
• Motivations and theoretical status
• The Lattice QCD calculation

LNF June 7-11 2004
In collaboration with D.Becirevic, G.Isidori,
G.Martinelli, F.Mescia, S.Simula, C.Tarantino,
G.Villadoro
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MOTIVATIONS
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The NEW experimental results
BNL-E865 PRL 91, 261802 (Moriond 04)
KTeV hep-ex/0406001
KLOE Moriond 04
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Theoretical description
THE LARGEST UNCERTAINTY IS DUE TO THE FORM
FACTOR AT ZERO MOMENTUM TRANSFER f(0)
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ChPT The complete O(p6) calculation
Post, Schilcher (2001), Bijnens, Talavera
(2003) C12 (µ) and C34 (µ) can be determined
from the slope and the curvature of the scalar
form factor. Experimental data, however, are not
accurate enough.
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Lattice QCD calculation the strategy
D.Becirevic, G.Isidori, V.L., G.Martinelli,
F.Mescia, S.Simula, C.Tarantino, G.Villadoro.
hep-ph/0403217
3) Subtraction of the chiral logs (we compute ?f
f(0)-1-f2 ) and extrapolation to the
physical meson masses
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The basic ingredient is a double ratio of
correlation functions
FNAL
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(No Transcript)
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3) Subtraction of the chiral logs and chiral
extrapolation
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The dominant contributions to the systematic
error come from the uncertainties on the q2 and
mass dependencies of the form factor
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CONCLUSIONS
? We presented a quenched lattice study of the
K?p vector form factor at zero momentum transfer
? The calculation is the first one obtained by
using a non-perturbative method based only on
QCD, except for the quenched approximation
? Our final result, f (0) 0.960 0.005stat
0.007syst is in good agreement with the estimate
made by Leutwyler and Roos and quoted by the PDG
? In order to increase the accuracy of the
theoretical prediction the most important step is
to remove the quenched approximation