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spectral function → a μ , α PowerPoint Presentation
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spectral function → a μ , α
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  1. 1. Motivation • spectral function → aμ , α Dominant uncertainty comes from experimentally determined hadronic loops: Mitchell Naisbit Manchester Jan2004

  2. 2. Motivation cont’d Recent results show discrepancy between and spectral functions Babar ideal to validate τ result.

  3. 3. Aim • Study ρ line shape → Assess contribution from ρ(1450) and ρ(1700) • Make a selection of signal events, maximising the efficiency and purity • Form invariant mass spectrum of the system.

  4. 4. Samples Produced using TauUser package 19 fb-1 of run 1, 2 and 3 data (124 fb-1) 60 M τ Events 130 M uds events small bhabha samples

  5. 5. Selection Procedure Selection for data and MC samples: Use 1-1 events and tag to reduce backgrounds Signal sideTag side • Truth-match to calculate ε and π: • particle ID • same mothers

  6. 6. Invariant Mass Spectrum ε = 9.6 % π = 55.1 % • τ background dominant, seen to be: • mostly a1 decays where 1 πo is lost • improperly reconstructed signal decays

  7. 7. Tag Invariant Mass Spectra e-tag = bhabha background, low uds μ-tag = no bhabha, low uds ρ-tag = uds background, no bhabha

  8. 8. Future Work • Running on the entire 124fb-1 sample: • Apply cuts to subtract remaining backgrounds and optimiseε and π • Unfold detector effects from invariant mass spectrum • Perform fits to spectrum to assess contributions from higher ρ resonances.