Jet reconstruction and underlying event studies in p+p and d+Au   collisions from STAR
  Description of parton interaction with the hot and dense nuclear matter created in heavy-ion collisions at high energies is a complex task, which requires a detailed knowledge of jet production in p+p and d+Au collisions. Measurements in these collision systems are therefore essential to disentangle initial state nuclear effects from cold nuclear matter effects, medium-induced $k_T$ broadening and jet quenching. To obtain complete description of the p+p (d+Au) collision it is also important to study particle production in the underlying event. The measured properties of underlying event can be used to tune the QCD based Monte-Carlo models.   In this paper some of the recent results on jet and underlying event properties in p+p and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured by the STAR experiment are presented. In particular, the preliminary results on charged and strange particle fragmentation functions in p+p collisions are discussed and confronted with PYTHIA simulations. Next, the measurement of inclusive jet spectrum and di-jet correlations in d+Au collisions is presented and compared with the measurements in p+p collisions to estimate the size of cold nuclear matter effects. Finally, the study of underlying event properties in p+p collisions is shown and compared to PYTHIA simulation. 
Jana Bielcikova (the STAR Collaboration)
nucl-ex