Abstract
We present results for the measurement of meson production via its charged kaon decay channel in collisions at , and 200 GeV, and in and collisions at GeV from the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC). The midrapidity () meson transverse momentum () spectra in central collisions are found to be well described by a single exponential distribution. On the other hand, the spectra from , , and peripheral collisions show power-law tails at intermediate and high and are described better by Levy distributions. The constant yield ratio vs beam species, collision centrality, and colliding energy is in contradiction with expectations from models having kaon coalescence as the dominant mechanism for production at RHIC. The yield ratio as a function of is consistent with a model based on the recombination of thermal quarks up to GeV/, but disagrees at higher transverse momenta. The measured nuclear modification factor, , for the meson increases above unity at intermediate , similar to that for pions and protons, while is suppressed due to the energy loss effect in central collisions. Number of constituent quark scaling of both and for the meson with respect to other hadrons in collisions at GeV at intermediate is observed. These observations support quark coalescence as being the dominant mechanism of hadronization in the intermediate region at RHIC.
14 More- Received 17 September 2008
DOI:https://doi.org/10.1103/PhysRevC.79.064903
©2009 American Physical Society