An Update of the HLS Estimate of the Muon g-2
release_uvlfbtqg55aqdpkfxtnojdt7ee
by
M. Benayoun, P. David, L. DelBuono, F. Jegerlehner
2012
Abstract
A global fit of parameters allows us to pin down the Hidden Local Symmetry
(HLS) effective Lagrangian, which we apply for the prediction of the leading
hadronic vacuum polarization contribution to the muon g-2. The latter is
dominated by the annihilation channel e+e- -> pi+pi-, for which data are
available by scan (CMD-2 and SND) and ISR (KLOE-2008, KLOE-2010 and BaBar)
experiments. It is well known that the different data sets are not in
satisfactory agreement. In fact it is possible to fix the model parameters
without using the pi+pi- data, by using instead the dipion spectra measured in
the tau decays together with experimental spectra for the pi0 gamma, eta gamma,
pi+pi-pi0, K+K-, K0bar K0 final states supplemented by specific meson decay
properties. Among these, the accepted decay width for rho0 -> e+e- and the
partial widths and phase information for the omega/phi -> pi+pi- transitions,
are considered. It is then shown that, relying on this global data set, the HLS
model, appropriately broken, allows to predict accurately the pion form factor
up to 1.05 GeV. It is shown that the data samples provided by CMD-2, SND and
KLOE-2010 behave consistently with each other and with the other considered
data. Consistency problems with the KLOE-2008 and BaBar data samples are
substantiated. "All data" global fits are investigated by applying reweighting
the conflicting data sets. Constraining to our best fit, the broken HLS model
yields a_mu(th) = (11659169.55 [+1.26 -0.59]_phi +[+0.00 -2.00]_tau +/-
5.21_(th))~10**-10 associated with a very good global fit probability.
Correspondingly, we find that Delta a_mu=a_mu (exp)- a_mu (th) exhibits a
significance ranging between 4.7 and 4.9 sigma.
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