Accepted Tuesday Oct 13, 2009
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 non-zero value of the mixing angle q13. Here we show that, likewise, non-standard 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 q13. 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 q13 and the vectorial coupling \epsetdV characterizing the non-standard transitions between ne and nt in the forward scattering process with d-type quarks. We find that couplings with magnitude \epsetdV ~ 10%, compatible with the existing bounds, can mimic the non-zero values of q13 indicated by the latest analyses.