1110.0579 (STAR Collaboration)

Identified hadron compositions in p+p and Au+Au collisions at high
transverse momenta at $\sqrt{s_{_{NN}}} = 200$ GeV    [PDF]

STAR Collaboration

We report transverse momentum ($p_{T}
\leq15$ GeV/$c$) spectra of $\pi^{\pm}$, $K^{\pm}$, $p$, $\bar{p}$,
$K_{S}^{0}$, and $\rho^{0}$ at mid-rapidity in p+p and Au+Au collisions at
$\sqrt{s_{_{NN}}}$ = 200 GeV. Perturbative QCD calculations are consistent with
$\pi^{\pm}$ spectra in p+p collisions but do not reproduce $K$ and $p(\bar{p})$
spectra. The observed decreasing antiparticle-to-particle ratios with
increasing $p_T$ provide experimental evidence for varying quark and gluon jet
contributions to high-$p_T$ hadron yields. The relative hadron abundances in
Au+Au at $p_{T}{}^{>}_{\sim}8$ GeV/$c$ are measured to be similar to the p+p
results, despite the expected Casimir effect for parton energy loss.

View original: http://arxiv.org/abs/1110.0579