Multiplicity distribution of colour dipoles at small x Original Research Article

The colour dipole multiplicity distribution is analysed for the wave function of a heavy onium state at small x. Numerical results for the average multiplicity and the effect of cutoffs on its power growth are presented. Then, the full multiplicity distribution is analysed: the second multiplicity moment is derived and the tail of the distribution is shown to behave as exp(− log2n). These results are confirmed by a Monte Carlo simulation which also gives the fluctuations in the spatial density of dipoles.