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A FB at LHC

A FB at LHC. Myfanwy Liles (University of Liverpool) Ronan McNulty (University College Dublin) Tara Shears (University of Liverpool). LHCEWWG 5.04.2011. Outline. Is it worth trying to measure A FB at LHC? Rather simple and unsophisticated study Horace Pythia

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A FB at LHC

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  1. AFB at LHC Myfanwy Liles (University of Liverpool) Ronan McNulty (University College Dublin) Tara Shears (University of Liverpool) LHCEWWG 5.04.2011 Ronan McNulty, LHCEWWG, 5.04.2011

  2. Outline • Is it worth trying to measure AFB at LHC? • Rather simple and unsophisticated study • Horace • Pythia • Motivate discussion and ideas Ronan McNulty, LHCEWWG, 5.04.2011

  3. Current precision on sin2qW Unsatisfactory that two most precise measurements are >3s apart, and that W.A. is marginally consistent with either. Would like to make measurement with precision of ~0.0001. Ronan McNulty, LHCEWWG, 5.04.2011

  4. HORACE: O()+-ind. 7TeV. All rapidities. AFB away from Z pole • Strong dependence with mass due to -Z interference. (To first order, zero on pole). “Asymmetry greater further from pole” Ronan McNulty, LHCEWWG, 5.04.2011

  5. AFB away from Z pole • On pole, due to different RH, LH Z coupling… • Small positive value HORACE: O()+-ind. 7TeV. All rapidities. Ronan McNulty, LHCEWWG, 5.04.2011

  6. AFB on Z pole AFB in muon channel at LHC is about 5 times larger than at LEP. But sensitivity coming more from Al rather than Au or Ad Ronan McNulty, LHCEWWG, 5.04.2011

  7. Where are we most sensitive? HORACE: Born 7TeV. All rapidities. Greatest sensitivity per event at 82 GeV About 2/3 that sensitivity at 91 GeV But much more stats. So measurement on pole appears most sensitive to sin2q far from pole HORACE: Born 7TeV. All rapidities. near pole Ronan McNulty, LHCEWWG, 5.04.2011

  8. Problems for LHC Ronan McNulty, LHCEWWG, 5.04.2011

  9. Going forward increases AFB HORACE: Born 7TeV. 89.2<m<93.2. Ronan McNulty, LHCEWWG, 5.04.2011

  10. Going forward increases sensitivity… HORACE: Born 7TeV. 86.2<m<96.2. Ronan McNulty, LHCEWWG, 5.04.2011

  11. HORACE: Born 7TeV. Stat uncertainty 10fb-1 Stat uncertainty 50fb-1 Ronan McNulty, LHCEWWG, 5.04.2011

  12. 50fb-1 at 14 TeV measures sin2q~0.0001 1fb-1 HORACE: Born 14TeV. 10fb-1 50fb-1 Stat uncertainty 10fb-1 Stat uncertainty 50fb-1 Ronan McNulty, LHCEWWG, 5.04.2011

  13. 50fb-1 at 14 TeV measures sin2q~0.0001 1fb-1 HORACE: Born 14TeV. 10fb-1 50fb-1 Stat uncertainty 10fb-1 • How confident are we: • - of theory? • - of PDF uncertainties? • of detector systematics? Stat uncertainty 50fb-1 Ronan McNulty, LHCEWWG, 5.04.2011

  14. Uncertainty due to PDF Uncertainty from PDF (from one PDF set) about the same as statistical uncertainty. With time, this should improve (~ 50%?) For 3<yZ<4 0.0004 AFB calculated MSTW Eigenvector number Ronan McNulty, LHCEWWG, 5.04.2011

  15. Uncertainty due to PDF HORACE: Born 7TeV. 86.2<m<96.2. Difference between two (old) PDF sets about the same as statistical uncertainty. 0.0004 Ronan McNulty, LHCEWWG, 5.04.2011

  16. Conclusions • Is it worth trying to measure AFB at LHC? • …. Probably. Ronan McNulty, LHCEWWG, 5.04.2011

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