High-energy factorization predictions for the charm structure function F^c₂ at HERA

High-energy factorization predictions for F^c₂ are derived using BFKL descriptions of the proton structure function F₂ at HERA. The model parameters are fixed by a fit of F₂ at small x. Two different approaches of the non-perturbative proton input are shown to correspond to the factorization at the gluon or quark level, respectively. The predictions for F^c₂ are in agreement with the data within the present error bars. However, the photon wave-function formulation (factorization at quark level) predicts significantly higher F^c₂ than both gluon factorization and a next-leading order DGLAP model.