functions [@LQS1]. Inside a large nucleus, multiple scattering can take place within one nucleon or between different nucleons. At high energy, a single hard scattering is always localized within one nucleon, and it cannot generate any large dependence on the nuclear size. Similarly, multiple scattering within one nucleon cannot provide much dependence on the nuclear size either. Therefore, the large dependence on the nuclear size is an unique signal of multiple scattering between nucleons. Measurements of such anomalous dependence on the nuclear size for any physical observable will provide direct information on multiparton correlation functions in a nucleus.

However, there are many multiparton correlation functions in QCD [@LQS1]. It is therefore important to identify physical observables which depend only on a small number of multiparton correlation functions. Otherwise, data will not be able to separate contributions from different correlation functions. It was pointed out recently in Ref. [@Guo2] that the $A^{1/3}$-type enhancement of the transverse momentum broadening of Drell-Yan pairs and the jet broadening in lepton-nucleus deeply inelastic scattering (DIS) are good observables, because at the leading order of $\alpha_s$, these two observables depend only on one type of multiparton correlation functions. It represents the correlations between hard quarks and 