LVL1, LVL2 low pT muon triggers efficiency calibrations
with J/Y Upsilon and non resonant di-muons from B-events
Hironori Kiyamura (Kobe)
Takanori Kono, Cristobal Padilla (CERN)
Daniel Scheirich (Prague)
Shlomit Tarem, Natalia Panikashvili (Technion)
LVL1 di-muon trigger efficiency calculation
• Single muon trigger efficiency
• Di-muon trigger efficiency
• Summary and outlook
Status of CSC note 07
• Contents of the note
• Status of the note
2007/09/03 B-physics meeting 2
LVL1 di-muon trigger efficiency calculation
• Estimate Di-muon Trigger Efficiency using real data.
– Identify pre-scaled trigger is needed for this study.
• Measure single muon trigger efficiency using J/Y -> mm process.
• From the result, make Trigger Efficiency Map for each (pt,h,f).
Single muon trigger efficiency will be obtained from this map.
• Calculate di-muon trigger efficiency as the products of two muon’s
Data samples (AOD,ESD)
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LVL1 trigger configuration 900GeV configuration
900GeV trigger configuration is slightly different with normal one.
1MU06 trigger efficiency is different between these two configurations.
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Muon reconstruction efficiency
The difference is large
for low pt muons.
▲ StacoCombined muons (triggered)
▲ StacoCombined muons (not triggered)
MuonBoy muons (triggered)
MuonBoy muons (not triggered)
Reconstruction efficiency depends on whether muon is triggered or not.
We need to understand the correlation between trigger and offline.
We will measure LVL1 trigger efficiency for reconstructed muons.
2007/09/03 B-physics meeting 6
Single muon trigger efficiency measurement
Leg technique Step.1 seed muon(MU06)
dR dh 2 df 2
probe muon Trigger judgment
J/Y dR matching between
(2.88GeV<Mmm<3.3GeV) ROI and Hits on track.
-> dR<0.1 -> triggered
• Use only MU06 triggered events and Muonboy reconstructed muons
1. Look for MU06 triggered muon in both barrel and endcap
-> seed muon
2. Look for another muon of decay products from J/Y -> probe muon
3. Using the probe muon, single muon trigger efficiency is calculated.
• With this method, single muon trigger efficiency is calculated and
validated by comparing with single muon samples.
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Single muon trigger efficiency for pt Obtained by J/Y -> mm samples
Single m (reconstructed by Mboy)
Single m (all muons)
1 exp ( a(pt b))
• No bias exist in the results of single muon samples.
For reconstructed muons, the efficiency from data (black square) matches
well with that of single muon sample (red square).
This method works well !!
※ Discrepancy is observed in single muon efficiency by requiring offline
reconstructed muons. (mentioned in slide #5)
Next -> Divide this result to make trigger efficiency map.
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Single muon trigger efficiency for each (h,f) region (BARREL)
Barrel is divided into 10 regions for h and f respectively.
In some bins, points below 4GeV are missing and the fit doesn't work quite well.
-> Need sample with mu6+mu0
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Single muon trigger efficiency for each (h,f) region (ENDCAP)
8 octants are merged and divided into 10/6 regions for h/f respectively.
IDf = 0 IDf = 5
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Trigger efficiency map
Fitting parameters are recorded with the center position of each region.
Recorded values are linearly extrapolated to all over Endcap/Barrel.
A a b
A a b
(A,a,b) values at (h,f) are obtained from these maps.
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Di-muon trigger efficiency calculation
• Single muon trigger efficiency : m1(pt1,h1,f1), m2(pt2,h2,f2)
(These two values are obtained from trigger efficiency map)
• Di-muon trigger efficiency : mm = m1×m2
Trigger efficiency for J/Y events can be calculated as following,
– Define q as the decay angle of muons from J/Y and P as the
momentum of J/Y.
LAB m1 (pt1,h1,f1)
These values are
Direction of J/Y P decided by (q,P).
J / Y f (q ) f ( p) mm dqdp q and P distributions are needed.
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Validation of di-muon trigger efficiency measurement
• The result using trigger efficiency map is compared
with that using L1_2MU06 flag.
• For this study, use only J/Y reconstructed events.
• Define di-muon trigger efficiency in two ways;
# of L1_2MU06 events
1 ε flag results
# of J/Y reconstruc events
ε flag 53.0%
2 ε m ap
ε μ1ε μ2
# of J/Ψ reconstructed events ε map 53.7%
These two results are matched within 1%.
-> Trigger efficiency map seems to work well.
-> Error estimation should be done for the next step.
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Fake J/Y ratio is estimated by counting the number of events
in 2.88GeV < Mmm < 3.3GeV.
From signal samples
bbmu6X Dijet samples
Fit only background
Main background is J1,J2
Fake J/Y ratio
※ More statistics are needed.
bbmu6X:9.3%, Dijet:14.7% -> total 24.0%
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Summary and outlook
• Single muon trigger efficiency is calculated with J/Y -> mm samples.
※ Identify pre-scaled trigger is needed for this study.
The efficiency is well matched with that of single muon samples.
The method seems to work well.
• Trigger efficiency map is made and di-muon trigger efficiency is
calculated for J/Y reconstructed events.
The result matches with that of using L1_2MU06 flag within 1%.
The method seems to work well, too.
※ Samples including lower pt muons are needed for trigger efficiency map !!
• Background effects are estimated on bbmu6X and di-jet samples.
For dijet samples, more statistics are needed.
• Calculate J/Y di-muon trigger efficiency.
• Estimate errors in di-muon trigger efficiency calculation.
• Use MU10 muon as seed muon and compare with the case of MU06.
(trigger rate, statistics, etc…)
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Status of B-physics CSC note 7
B-physics CSC note 7
Contents of the note
• Method for obtaining trigger efficiency from data
– Single muon efficiency at low-pT
– Di-muon efficiency
• Proposal of calibration triggers
– Calibration triggers necessary for MU6, 2MU6, MU6+X (basically, a
prescaled single muon trigger)
– J/psi signal events and trigger rate by the calibration trigger with respect to
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Status of the note
• Writing of the note has not started yet
– Twiki page: CSCBPhysicsTask7
– LVL1 study in a good shape
• Demonstration of the method single muon efficiency done (comparison with
single muon sample)
• Expect to have the comparison of the obtained di-muon efficiency with truth soon
– LVL2 study in a good shape for 2MU6, but the study just starting for
• Need reconstruction by release 13 for TrigDiMuon
– Consideration on the choice of thresholds and prescaled for the single muon
trigger for calibration
• Plan to finish by the end of the year
2007/09/03 B-physics meeting 18