Muon momentum scale calibration with J/y peak PRELIMINARY: low statistics in data not final MC (low stat used) First pass on the data: many details to be investigated

Samples and cuts Data (~15 nb-1): May6 Re-Reco from 132440 to 134725 Onia-CS-V9 up to 135735 Mu-CS-V1 up to 136086 (CMSSW_3_5_8_patch3) Mu-CS-V2 up to 136561 (max useful 136297) (CMSSW_3_6_1_patch2) BPH Json file applied MC (~100 nb-1): Spring10 J/y prompt + ppMuMuX Standard onia selection: global muon: nHits inner track > 11 tracker muon: nHits inner track > 11 pixelLayer >1 pixelLayer >1 d0<5 cm, |dZ|<20 cm d0<5 cm, |dZ|<20 cm chi2 < 20 chi2 < 5 TMLastStationAngTight Exclusive cathegories: glb-glb if any, otherwise glb-trk (inner track always used, also for glb muons) No trigger, no acceptance cuts

Mass peak (nominal mass 3.0969 GeV) Fit: CrystalBall (to include FSR tail) + exponential for the background DATA: mean (3.092 ± 0.001) GeV MC: mean (3.0976 ± 0.0006) GeV sigma (43 ± 1) MeV sigma (37.3 ± 5) MeV Data have 5MeV bias and worse resolution (and larger background)… … BUT the pT, h distribution of J/y is quite different in data and MC (to be checked)

Mass reso VS muon kinematics data data |h| 1.6 MC MC pT 1.4 GeV |h| 0 pT 4.6 GeV

Mass scale VS muon kinematics MC (1.38 pb-1 Spring10 prompt J/y) Also in MC we have scale bias bias in the reco algorithm approximated material budget in reconstruction Gaussian fit in each pT, h bin: bias < 5 MeV FSR not considered (→ CB with more stat) bins are large: integration over different eta/pt distribution btw data and MC

Inner VS global tracks GG+GT GG: inner tracks GG: global tracks No significative difference with this statistics

MuScle fit peak+FSR convoluted with gaussian for resolution (FSR from fit of generated mass distribution) Fit reconstructed mass profile with signal model + exponential background ansatz functions for single muon scale and reso compute m, s(m) (with error propagation) event by event unbinned likelihood multiparameter fit → two muons can probe uncorrelated detector regions → correlation between different kinematic variables taken into account extract scale and resolution on single track as a function of muon kinematics a0 = 1.0019 ± 0.0008 2‰ effect a1 = (-4 ± 2)·10-4 GeV-1 1‰ at 3 GeV b0 = 1.66 ± 0.09 b1 = (5.8 ± 0.9)·10-3 b2 = (2.1 ± 0.2)·10-2 bad fit for high h parabola (to be checked with more stat) b3 = (3 ± 3)·10-2 b4 = 1.8 ± 0.3

Mass after corrections Raw Calibrated m = 3.092 ± 0.001 m =3.094± 0.001

Crystal Ball is an approximation Model computed analytically: fit to the generated mass spectrum gaussian for the resolution 2D model mass VS s peak shift at high s If you fit this model with Crystal Ball → 2MeV shift in the mean

Resolution: PRELIMINARY Resolution from MuScle fit !! large uncertainties not plotted !! hints of worse resolution in dat at high h (confirmed by plot in slide 4) DATA s(M) GeV Width of gaussian fit in each f bin sinusoidal shape (??) mu - mu + c0 42±1 MeV 45±1 MeV c1 -4±2 MeV -4±2 MeV c2 1.5±0.5 0.5±0.5

Final aims Commissioning: measure pT resolution from data and compare with MC measure scale bias in data → provide corrections → compare with expected effects from misaligment, magnetic field, material budget (tested in MC) Usage in physics analyses: onia ds/dpT measured with corrected momenta → remaining systematics due to correction uncertainty systematics on onia acceptance due to different MC-data scale and resolution (full scale bias in MC + data uncertainty) used for systematics (difference in resolution between data and MC + data uncertainty) used for systematics VBTF: extrapolation of results to Z