1. A Feasibility Study on Measuring a Strange Sea Asymmetry in the Proton 14/07/05Laura Gilbert, Jeff Tseng

2. Possible strange sea asymmetry xs(x)≠xs(x)? More sensitive to smaller x with W searches. Eg. NuTeV anomaly: in sin 2 θ W measurements. Signal & Cao suggest that a strange sea asymmetry could reduce the discrepancy in sin 2 θ W from 3σ→~2σ. The physics… s cg W

3. Technique HepMC DC2 sample of W→eν e. 240k events before trigger cuts, ~21k after. Reconstruct D 0 →Kπ (also D 0 →Kππ 0, D 0 →Kπππ) Add soft (prompt) pion to reconstruct D *+. Proper time → 123 μm flight Count opposite sign combinations of W, D *. Count same sign backgrounds.

4. Mass difference plots One electron track with Pt>25GeV, missing Et>25GeV, η<2.4 (W tagging) Pt of Kaon candidate > 1.5GeV, pion pt > 1.0GeV (combined to D 0 ) Pt of batchelor pion > 0.9GeV Plotted mass difference: reconstructed D * - K π. Peak around 145MeV. Atlfast - unsmearedAtlfast - smeared

5. Future Plans Probably difficult to study! Increase statistics Study backgrounds and pile-up at low/high luminosity Full simulation needed (look at alignment, multiple scattering for very low pt tracks to get soft pion efficiency, systematic uncertainties)