estimate given in [@Gasser:1983yg]: $$\label{eq:l3}
\bar l_3 = 2.9\pm2.4\,.$$

The scalar radius was used as input in [@Colangelo:2001df]. From the value above they derived $$\label{eq:l4}
\bar l_4 = 4.4\pm0.2\,.$$ This value is in good agreement with the determination done in [@Bijnens:1998fm] directly from the scalar radius.

The constant $\bar l_5$ is quite well known. It can be determined from the difference between vector and axial-vector two-point functions. The analysis in [@GonzalezAlonso:2008rf] quotes $$\label{eq:l5}
\bar l_5 = 12.24\pm0.21\,.$$

The constant $\bar l_6$ can be determined from the pion electromagnetic radius. This was done in [@Bijnens:1998fm] and gives the value $$\label{eq:l6}
\bar l_6 = 16.0\pm0.5\pm0.7\,.$$ The last error is mainly from the estimate of the $c^r_i$.

A combination of the latter two can be obtained from the axial form factor $F_A$ in the decay $\pi^+\to e^+\nu\gamma$. The two-loop calculation was done in [@Bijnens:1996wm] with the result $$\label{eq:l5l6}
\bar l_5-\bar l_6 = - 3.0\pm0.3\,.$$ Ref. [@Bijnens:1996wm] used $F_A= 0.0116\pm0.0016$ from the measured value for $\gamma=F_A/F_V$ and the CVC prediction for $F_V$. $F_V$ and $F_A$ have since been measured with better precision with the result from [@Bychkov:2008ws] being $F_A=0.0117\pm0.0017$ so the value in (\[eq:l5l6\]) does not change.

Note that the values in (\[eq:l5\]) and 