Can STAR $p+p$ data help constrain fragmentation functions for strange hadrons

Abstract

STAR has measured a variety of strange particle species in $p+p$ collisions at $\sqrt{s}$=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 pt-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 Lambda 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 pt (2-6 GeV/c), which may be a first indication of other, non-perturbative mechanisms at play in $p+p$ collisions at that momentum.