Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lattice QCD calculation of the pion charge radius using a
  model-independent method   We use a method to calculate the hadron's charge radius without
model-dependent momentum extrapolations. The method does not require the
additional quark propagator inversions on the twisted boundary conditions or
the computation of the momentum derivatives of quark propagators and thus is
easy to implement. We apply this method to the calculation of pion charge
radius $\langle r_\pi^2\rangle$. For comparison, we also determine $\langle
r_\pi^2\rangle$ with the traditional approach of computing the slope of the
form factors. The new method produces results consistent with those from the
traditional method and with statistical errors 1.5-1.9 times smaller. For the
four gauge ensembles at the physical pion masses, the statistical errors of
$\langle r_\pi^2\rangle$ range from 2.1% to 4.6% by using $\lesssim50$
configurations. For the ensemble at $m_\pi\approx 340$ MeV, the statistical
uncertainty is even reduced to a sub-percent level.

25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an