Speaker
K. Oleg Eyser
(UC Riverside, DESY)
Description
With recent experimental measurements of various asymmetries at HERMES[1], Belle[2],
STAR[3], and BRAHMS[4] there has been a growing interest in the understanding of the
transversely polarized proton structure. Theoretical explanations include different
mechanisms, such as effects from the Sivers function, the Collins effect, higher
twist contributions, or combinations of all of the above. In order to quantify
contributions from competing mechanisms, measurements over a wide range of p_T and
x_F are needed.
PHENIX, one of the two large experiments the Relativistic Heavy Ion Collider (RHIC),
has accumulated a substantial transversely polarized data set over the last few
years. Measurements include inclusive single spin asymmetries at mid-rapidities at
sqrt{s} = 200 GeV [5]. In 2006, new data sets of 2.7 pb^{-1} at srqt{s} = 200 GeV and
20 nb^{-1} at sqrt{s} = 62.4 GeV have been taken. A new calorimeter at large rapidity
installed during the 2006 run allows PHENIX to measure an even broader spectrum of
the probes proposed to help disentangle contributions from the various theoretical
models.
We present the status of the PHENIX measurements and how they can help to lead to a
deeper understanding of the transverse proton spin structure.
1. A. Airapetian et al., Phys. Rev. Lett. 94, (2005) 012002.
2. R. Seidl et al., Phys. Rev. Lett. 96 (2006) 232002.
3. J. Adams et al., Phys. Rev. Lett. 92 (2004) 171801.
4. F. Videbaek et al., AIP Conf. Proc. 792 (2005) 993.
5. S.S. Adler et al., Phys. Rev. Lett. 95 (2005) 202001.
Author
K. Oleg Eyser
(UC Riverside, DESY)
