Analysis of x F 3 : QCD and higher twist

We have analysed all available data on the non-singlet neutrino structure functionxF3 taking into account systematic errors and EMC corrections. A good fit to all data withQ2≧5 (GeV/c)2,W2≧10 (GeV/c)2 is obtained neglecting higher twist contributions, with Λ=0.18±0.07 GeV, corresponding toα s (Q2=25(GeV/c)2)=0.18±0.02. On lowering the cuts toQ2≧3 (GeV/c)2,W2≧3 (GeV/c)2, we find evidence for a small negative higher-twist term. Incorporating such a term in a simple parametrisation yields an increased Λ value of 0.27±0.05 GeV, corresponding toα s (Q2=25(GeV/c)2)=0.20±0.01.