Soft neutron production in DIS: a window to the final state interactions

Recently E-665 reported the first measurement of soft (E-n less than or equ al to 10 MeV) neutron production in deep inelastic scattering (DIS) off nuc lei. We report the first theoretical analysis of the data. We find that the observed cross section can be quantitatively explained as due to the final state interactions (FSI) of low energy nucleons (E-N similar to 200-400 Me V) produced in the elementary mu N interactions. We argue that the data ind icate strong a suppression of the FSI's of fast partons (hadrons) in DIS at high energies, and that studies of the soft neutron production would provi de a new sensitive probe of the dynamics of FSI's in DIS both at fixed targ et energies and at the HERA eA collider. (C) 1999 Elsevier Science B.V. All rights reserved.