Solar and KamLAND data are in slight tension when interpreted in the standard two-flavor oscillations framework and this may be alleviated allowing for a nonzero value of the mixing angle \theta _ { 13 } .
Here we show that , likewise , nonstandard flavor-changing interactions ( FCI ) , possibly intervening in the propagation of solar neutrinos , are equally able to alleviate this tension and therefore constitute a potential source of confusion in the determination of \theta _ { 13 } .
By performing a full three-flavor analysis of solar and KamLAND data in presence of FCI we provide a quantitative description of the degeneracy existing between \theta _ { 13 } and the vectorial coupling \epsilon _ { e \tau } ^ { { \mathrm { d } } V } characterizing the nonstandard transitions between \nu _ { e } and \nu _ { \tau } in the forward scattering process with d-type quarks .
We find that couplings with magnitude \epsilon _ { e \tau } ^ { { \mathrm { d } } V } \sim 10 % , compatible with the existing bounds , can mimic the nonzero values of \theta _ { 13 } indicated by the latest analyses .