Univ Frankfurt, Inst Kernphys, D-6000 Frankfurt, Germany
; Huazhong Normal Univ, Inst Particle Phys, Wuhan, Peoples R China
; Inst High Energy Phys, Beijing 100039, Peoples R China
Transverse momentum event-by-event fluctuations are studied within the string-hadronic model of high energy nuclear collisions, LUCIAE. Data on non-statistical p(T) fluctuations in p + p interactions are reproduced. Fluctuations of similar magnitude are predicted for nucleus-nucleus collisions, in contradiction to the preliminary NA49 results. The introduction of a string clustering mechanism (Firecracker Model) leads to a further, significant increase of p(T) fluctuations for nucleus-nucleus collisions. Secondary hadronic interactions, as implemented in LUCIAE, cause only a small reduction of p(T) fluctuations.