Marco Stratmann Regensburg / Wurzburg What can be done with possible He3 W-boson A L data RSC meeting, Ames, Iowa, May 14 th - 16 th,

 based on parity violation: W’s couple only to one parton helicity key measurement at RHIC study single spin asymmetries  RHIC: can detect only decay leptons; lepton rapidity most suited observable strong correlation with x 1,2 allows for flavor separation for x > 0.07 new versatile NLO MC code “CHE” available de Florian, Vogelsang, arXiv:  neat handle on flavor separation in global analysis; large asymmetries; large scale Q=M W where pQCD works easily implemented in global analysis 2

de Florian, Vogelsang t largeu large strong sensitivity to t largeu large limited sensitivity to 3

Δχ 2 = 2% uncertainty bands of DSSV analysis simulated impact of RHIC W boson data on global fit de Florian, Vogelsang reduction of uncertainties for 0.07 < x < 0.4 can test consistency of low Q 2 SIDIS data in that x regime “CHE” integrates nicely into DSSV global analysis code based on Mellin moments 4

GeV 5

need maximum possible c.m.s. energy: 216 GeV protons on 216 GeV/n He-3 (feasible? – otherwise W cross section too small) pros cons polarized He-3 mainly a neutron target: n + 2*(-0.027) p  important information for flavor separation complementary to pp cross section enhanced (nuclear “target”) need significant running time/luminosity for both pp and He-3 O(few hundred pb -1 ) each; but some “synergy effects” of combined set in global fit 6 unpolarized He-3 a combination of p and n  no longer probing Δ q/q as in pp; but irrelevant “complication“ in a global analysis

7 certainly an interesting avenue to arrive at a full u,d flavor separation at RHIC if we want to pursue this further, we can play with “pseudo data” not a free lunch – significant integrated luminosity needed would compete with other goals: more 200GeV running; transverse spin; … most likely, A L on its own does no justify the effort need a stronger physics case for He-3 at RHIC most likely, A L on its own does no justify the effort need a stronger physics case for He-3 at RHIC