Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pseudo-scalar meson form factors with maximally twisted Wilson fermions
  at Nf = 2   We present preliminary results for various electroweak form factors of
pseudo-scalar mesons using the tree-level improved Symanzik gauge action and
the maximally twisted mass fermionic action with Nf = 2 dynamical flavors. Our
results, obtained for both light and heavy quark masses at a single lattice
spacing (a ~ 0.09 fm) and at a single lattice volume (V * T = 24**3 * 48),
exhibit a quite remarkable statistical precision thanks to the use of
all-to-all quark propagators computed with a stochastic method. Moreover very
low values of the four-momentum transfer are achieved by making use of twisted
boundary conditions on the valence quark fields. The mass dependence of the
pion charge radius is analyzed using Chiral Perturbation Theory, obtaining
clear evidence of relevant two-loop contributions. The universal Isgur-Wise
function is computed from heavy-to-heavy electromagnetic transitions and its
slope in the case of $u(d)$ spectator quarks is found to be rho(IW)**2 = 0.77
+/- 0.28, where the error is statistical only.

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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
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The categories of this paper are: math
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The categories of this paper are: ao-sci
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: eess
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: gr-qc