1. 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

2. Samples and cuts Data (~15 nb-1): May6 Re-Reco from 132440 to 134725
Onia-CS-V9 up to
Mu-CS-V1 up to (CMSSW_3_5_8_patch3)
Mu-CS-V2 up to (max useful ) (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

3. 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 ( ± ) 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)

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

5. Mass scale VS muon kinematicsMC
(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

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

7. 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 = ±
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

8. Mass after corrections
Raw
Calibrated
m = ± 0.001
m =3.094± 0.001

9. 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

10. 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

11. 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