Missing ET with the First Data: Wl (l=e,) X.Chen, B.Mellado, S.Padhi and Sau Lan Wu (University of Wisconsin) Munich Workshop 03-05/05/06

Bruce Mellado, Munich Workshop Introduction Need control samples to evaluate and check the Missing ET performance with the very first data Need to address needs of discovery physics during the early stages of data taking Understanding of tails in missing ET will come form events with no (large) “real” missing energy: multi-jets, Z(ll)+jets Can also address resolution issues Use Wl as high statistics sample to check missing ET reconstruction with “real” missing energy Same check can be made with more luminosity with Z (ll)+jets (turn electrons into “neutrino”) Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop One can use the sharp end of the transverse mass in different missing ET bins Shape of transverse mass changes with Missing ET, due to acceptance One can also use the fact that in the average the pt of the charged lepton and the pt of the neutrino are of the W decay are known function, which can be calculated with MC Function can be calculated with MC (small uncertainties) and depends on experimental cuts Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop R calculated using truth No cuts PTL>20 GeV, |l|<2.5 Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop PTL>20 GeV, |l|<2.5 Fullsim (We) ATLFAST R calculated using truth Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop PTL>20 GeV, |l|<2.5 ATLFAST 100pb-1 +3% +2% Nominal Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop Back-up Slides Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop Outlook and Plans ppW(l, l=e, )+X is a copious source of events with missing energy. Expect 0(10K) per 1pb-1 With 100 pb-1 of data can check missing ET in most of useful range for low mass Higgs physics Allows to perform checks with different jet topologies Method is very sensitive to shifts in missing ET Less sensitive to missing ET resolution. This can be better constrained with di-jets Need to address luminosity required to study missing ET with different jet topologies Need to address contamination from top Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop PTL>20 GeV, |l|<2.5 Acceptance in W for PTL>20 GeV, |l|<2.5 Acceptance Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop PTL>20 GeV, |l|<2.5 Truth Solid histogram |W|< |W|<2 |W|>2 Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop PT>90 GeV Ratio No cuts PTL>20 GeV, |l|<2.5 Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop Events here were produced with Pythia Will re-do analysis with ALPGEN Expect harder PTW spectrum Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop Truth W, l Wl, l=e, Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop PTL>20 GeV, |l|<2.5 5 GeV Smearing 4 GeV 3 GeV 100pb-1 Nominal ATLFAST Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop PTL>20 GeV, |l|<2.5 ATLFAST 100pb-1 7 GeV smearing +3% shift Bruce Mellado, Munich Workshop

Bruce Mellado, Munich Workshop After the application of PTL>20 GeV, |l|<2.5 cuts the contribution from W, l amounts to few % of signal and can be easily subtracted with MC Wl, l=e, W, l W, l Bruce Mellado, Munich Workshop