STAR p + p data help constrain fragmentation func - tions for strange hadrons ”

" Can STAR p + p data help constrain fragmentation functions for strange hadrons " Mark T. Heinz (for the STAR collaboration) Abstract. STAR has measured a variety of strange particle species in p + p collisions at √ s = 200 GeV. These high statistics data are ideal for comparing to existing leading-and next-to-leading order perturbative QCD (pQCD) models. Leading-order (LO) models such as PYTHIA need to be tuned to describe identified strange particle data from STAR. We show that tuned PYTHIA can also describe the p T spectra of strange resonances. More rigorous Next-to-Leading order pQCD calculations using parameterized fragmentation functions for quarks and gluons will also be compared to STAR data. The OPAL experiment has recently released e + + e − data from light quark flavor tagged analyses allowing for the first time to make precise parameterizations of light flavor separated fragmentation function. We show that our Λ data put a more stringent constraint on the gluon fragmentation function than e + + e − data. Furthermore we show that pQCD fails to describe the observed enhancement of baryon-to-meson ratio at intermediate p T (2-6 GeV/c), which may be a first indication of other, non-perturbative mechanisms at play in p + p collisions at that momentum.