Pion fluctuation in deep inelastic scattering
  The forward neutron production in the ep collisions at 300 GeV measured by H1 and ZEUS Collaborations at DESY has been used to estimate the total probability for proton fluctuation into n pi^+ and p pi^0. The probability found is on the order of 30%. This number is compared with the numbers obtained for the probability of quark fluctuation into pi^+ from several alternative DIS processes (Gottfried sum rule, polarized structure function) and the axial-vector coupling constant, where the pion fluctuation is believed to play an important role. 
Armen Bunyatyan (1 and 2) and Bogdan Povh (1) ((1) Max-Planck-Institut   fuer Kernphysik, Hedeilberg, (2) Yerevan Physics In...