The energy-energy-correlator (EEC) observable in e+e- annihilation measures the energy deposited in two detectors as a function of the angle between the detectors. It is one of the earliest QCD observable designed to characterize the shape of hadronic energy flow in e+e- annihilation. Recently, there are renew interests in this observable from different perspectives, such as precision measurement of strong coupling constant, understanding the perturbative structure of QCD observable, and conformal collider physics. In this talk I will present two recent results on the EEC. In the first part, I will discuss the collinear limit of the EEC, where the angle between the two detectors approaches zero. I will present a factorization formula for the leading power asymptotic behavior in the collinear limit of a generic quantum field theory, which allows for the resummation of logarithmically enhanced terms to all orders by renormalization group evolution. In the second part, I will discuss the generalization of the EEC to hadron collider. I will present a factorization formula which can resum the large logarithms in the back-to-back limit of two detectors at hadron colliders.
