Color fluctuations in hadrons and proton coherent diffractive dissociation on helium

The differential cross section of inelastic coherent diffractive dissociation off nuclei p+4He X+4He is expressed in terms of the relative cumulants of the cross-section distribution PN(). The theoretical result for the ratio r=(ddiff/dt)t=0pHe/(ddiff/dt t=0pp=6.87.6 is close to the value r=7.10.7 which we extracted from the FNAL data. These are the only A2 data of this kind. The comparison provides the first confirmation of the color/cross-section fluctuation approach to the description of the absolute value of the inelastic diffraction cross section off nuclei. It provides also a new constraint on the first four cumulants of the cross-section distribution.