Pion form factor in QCD at intermediate momentum transfers - art. no. 073004

We present a quantitative analysis of the electromagnetic pion form factor in the light-cone sum rule approach, including radiative corrections and hi gher-twist effects. The comparison to the existing data favors the asymptot ic profile of the pion distribution amplitude and allows us to estimate the deviation: [integral dulu phi(pi)(u)]/[integral dulu phi(pi)(as)(u)] = 1.1 +/- 0.1 at the scale of 1 GeV. Special attention is paid to the precise def inition and interplay of soft and hard contributions at intermediate moment um transfer, and to the matching of the sum rule to the perturbative QCD pr ediction. We observe a strong numerical cancellation between the soft (end- point) contribution and power-suppressed hard contributions of higher twist , so that the total nonperturbative correction to the usual PQCD result tur ns out to be of the order of 30% for Q(2) similar to 1 GeV2.