Some First Artemis Standard Model Measurements Samira Hassani

Some First Artemis Standard Model Measurements Samira Hassani Saclay 1 st Artemis Annuel Meeting Chalkidiki, 26 -28 September 2007 26/09/07 1 st Artemis Meeting

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Muon Spectrometer Performance • Quantities measuring the spectrometer performance • Momentum resolution. • Track-reconstruction efficiency. • Quantities deteriorating the performance • Chamber inefficiencies. • Miscalibration of the MDT chambers. • Misalignment of the MDT chambers. • Errors of the magnetic-field map. 26/09/07 1 st Artemis Meeting 4

Measurement of Efficiencies in Data Tag and Probe Method to determine Efficiencies in Data N. Benekos, M. Schott, A. Wilson • Tag Muon: Track in Inner Detector AND Muon Spectrometer (+Isolation and p. T-Cuts) • Probe Muon: Track in Inner Detector (+Isolation and p. T-Cuts) • If this di-muon mass is 91 Ge. V ± 15 Gev and Δφ>2, then the probe muon is assumed to be a real muon: • muon efficiency is given by the fraction of probe muons with tracks in the Muon Spectrometer 26/09/07 1 st Artemis Meeting 5

Z→μμ Signal Selection • Main Backgrounds – QCD: dominated by the decay of bb→μμ – W→μν+jets – Z→т т→μμ • Selection cuts – Track PT > 20 Ge. V – Number of Tracks in Halo < 5 – Jet ET in Cone with Radius 0. 5 < 15 Ge. V – Track Isolation < 5 Ge. V – Di. Muon. Mass: 91 Ge. V± 15 Ge. V – Δφ>2 26/09/07 1 st Artemis Meeting 6

Efficiencies from Data 26/09/07 1 st Artemis Meeting 7

Determination of the p. T-Resolution with data • Idea: Use (again) the Z-Boson Resonance. • Try to smear the p. T of Monte-Carlo generated muons in such a way, that they will reproduce the measured Z -Boson distribution. • The smearing function can be taken from full simulation 26/09/07 1 st Artemis Meeting 8

Muon Isolation Efficiency • Use Tag and Probe Method to determine Muon Isolation Efficiency • Tag Muon: – – p. T>15 -20 Ge. V Isolated • Probe Muon: – – p. T>15 -20 Ge. V Together with Tag Muon gives Δφ>2 |91 Ge. V-Mμμ|<30 Test if probe muon is Isolated 26/09/07 1 st Artemis Meeting 9

From B-physics Working group: J/psi’s, Ypsilon expected with first 10 pb-1 Events 10 pb-1 including trig and offline efficiency pp J/y ( m 6 m 4 ) X 156 000 bb J/y ( m 6 m 4 ) X 78 000 pp ( m 6 m 4 ) 31 000 1 600 B+ → J/y K+ 900 N / 50 Me. V B 0 → J/y K*(K+p-) 105 Number of events with 10 pb-1 Results shown use mu 6 mu 4 triggers At 1031 cm-2 s-1 we may have more events with mu 4 triggers, but simulations not ready yet, so we show mu 6 mu 4 here. 104 103 26/09/07 1 st Artemis Meeting 10

From B-physics Working group: J/psi’s, Ypsilon with first 10 pb-1 One of first physics measurements may be the ratio of direct J/y to B →J/y and direct J/y to v Proper time use to measure ratio J/y direct/indirect (B-decays) v Free from uncertainties in luminosity and trigger efficiencies… v However needs validation of ID alignment to enable good vertexing ‘Mix’ sample is direct and indirect J/y combined 26/09/07 1 st Artemis Meeting 11

From B-physics Working group: Reference channel B+ J/y. K+ to be used as ID alignment tester already with 10 pb-1 Petridou, . Anastopoulos • B mass - lifetime fit – sensitive tests of detector alignments • No vertex displacement cuts (especially online) until ID alignments understood and validated. (2. 2%) B+ proper lifetime fit red B+ signal, black 26/09/07 background, blue all 1 st Artemis Meeting 12 World precision today (0. 67%)

First Artemis SM Measurement • For the Muon Spectrometer, we will be able to evaluate the: – Muon reconstruction efficiency – Muon isolation efficiency – Precision of Muon p. T-Resolution – Muon performance for low p. T muon from Jpsi and • For the Inner Detector, we can study the ID alignment using : – B+ proper lifetime measurement 26/09/07 1 st Artemis Meeting 13