anne dabrowski northwestern university collaboration meeting 22 nd february 2005 update kmu3...

Anne DabrowskiNorthwestern University

Collaboration Meeting22nd February 2005

Update Kmu3 Branching Ratio measurement

A. Dabrowski, February 22 2005

Test 2 Particle ID2 Particle ID muon strategies:

1) Muon Veto as Muon ID • Check muon veto status 1 or 2• Timing association of 2ns for track between muon

veto and hodoscope time

2) LKR and HAC as Muon ID● Use the mip signal in calorimeters:● LKR < 1.5 GeV and HAC < 5 GeV for the cluster

associated to the tracks..

Requirement for signal and normalisation:

● 1 track and 1 pi0● Kinematic cuts using LKR and DCH

Strategy: Measure Kmu3 Br normalised to pipi0


● Compact 7.2 & Database pass 5 Min bias 2003 (15745,15746 and 15747)

– Alignment

– E-baseline correction

– Bad burst

– Alphas and betas

– Projectivity and Blue Field

● MC Sample:– Ginsberg correction to Kmu3 – Evelina Marinova finalized

correction that Mengkei started

– DCH resolution from Eddy, and latest official updates

– Michal’s low energy correction to MC (not in presented Dec 2004 numbers)

Data Sample


Simple selection wanted....Common for Kmu3 and pipi0

● Track Section (no extra tracks allowed):

– 1 track after excluding Ghost-tracks – Hodoscope time window (-17. 20. ns)– Track quality > 0.8 CDA < 2.5 , Beta, alpha corrections from database– x,y vertex (-1.8,1.8) cm , z vertex (-500,8000)cm– Blue Field correction applied

● Pi0 Selection (extra gammas allowed for both)

– Energy of gamma (3, 65) GeV– Separation between gammas > 10 cm – Time difference between gammas (-5., 5.) ns– Pi0 mass cuts at 3 sigma and depends on pi0 energy

● For this talk I use Michals cut, and cut 3 sigma, In dec meeting, I used my old 2004 pi0 cut for the official numbers

– Projectivity correction– Latest Energy scale by Michal


Difference between Kmu3 and Pipi0 selection

● Kaon Mass (assuming pi) <0.475 or >0.515

GeV

● Mom (10, 40) GeV

● PT track (0.0, 0.2) GeV

● Nu mass (-0.01, 0.01) GeV2

● Dist between track & gammas > 10 cm

● Energy pi0 < 40 GeV

● COM pi0 < 0.24 GeV

● COM Track < 0.23 GeV

● Mass of mu pi0 < 0.445 GeV

● Particle ID for muons (2 methods used)Particle ID for muons (2 methods used)

● Kaon Mass (0.475,0.515) GeV

● Mom (10, 50) GeV

● PT track < 0.215

● Nu mass (-0.0025, 0.001) GeV2

● Distance between track & gammas > 35 cm

● PT pi0 < 0.220

● E/P < 0.95

● Use muon rejection only when the Use muon rejection only when the muon veto in used in the Kmu3 muon veto in used in the Kmu3 analysis. analysis.


Muon ID using the Muon Veto

• Muon ID efficiency calculated using Kμ2 sample from min bias run; – check status 1 or 2 and 2 ns

between hod time and muon veto time

• Kinematic cuts Momentum (10,40)– Banana PT vs P cut (Luca)– Mass ν2 (-0.02;0.01) GeV2

• Event Timing and Fiducial cuts as in Kmu3 Br analysis

• Efficiency between 0.997 and 0.998

• IN MC 6.4m decay volume, particle decay not simulated – Apply a correction to mc acceptance– See Michal Talk Torino

Method 1:Method 1:


Muon ID signals using the LKR and HAC

• Cuts chosen– LKR < 1.5 GeV and

HAC < 5 GeV• Muon sample using Kμ2

events from min bias run.

• Kinematic cuts– Momentum (10,40)– Banana PT vs P cut– Mass ν2 (-0.02;0.01) GeV2

– Muon Veto requested• Event Timing and Fiducial

cuts as in Kmu3 Br analysis

Method 2:Method 2:


Muon ID efficiency using the LKR and HACMethod 2:Method 2:

• Muon ID requirement:– LKR (cluster<1.5

GeV) and HAC (cluster<5.0 GeV)

– Muon ID is energy dependent with max ~0.987

– Analysis done bin by bin in momentum


Method 1 eff at 0.998

Corrected bi-nomial errors

Pion mis-identification as muons using the LKR

and HAC

• Pions can be to mis-identified as muons

– Need a pion mis-identification probability, and background subtraction.

• Sample used for calculating the mis-identification probability– Pions from my standard pipi0

selection, with the muon Veto requirement.

– Plus a tighter Kaon mass cut for this sample (0.485, 0.505 GeV).

– Event Timing and Fiducial cuts as in Kmu3 Br analysis

Method 2:Method 2:



● Main difference between this and the dec meeting:– 1. the pipi0 acceptance is defined as just those

events for which the pi+ does not decay .. So pipi0dk is a background to pipi0.

– For all analysis, the Number events = Ns(1+Ns/Nb) is used.

LKR HAC

Muon Veto

Comparison in result between 2 methods K+

No Background

No noBackground

# Events Data

Raw Acc MC

Acc * Particle ID (muon veto or E/P < 0.95)

Backgrounds

525248 532838 Kmu3 55905 0.1051 0.1049 ±0.0002 Pipi0dk 0.0133+-0.0007

Pipi0pi0dk 0.00111+-3x10-5

3186589 3186911 pipi0 488334 0.1541 0.1532±0.0003 Ke3 0.00010+-6x10-6

Correction due to pion decaying after LKR (0.993)

529125 536558 Kmu3 54623 0.1051 0.1018 ± 0.0002 Pipi0dk 0.0129+-0.0003

Pipi0pi0dk 0.00112+-3.3x10-5

3192325 324662 pipi0 497464 0.1541 0.1532 ±0.0003 Pipi0dk 0.013+-0.0062

Kmu3 0.00329+-7.6x10-5


Muon Veto

LKR HAC

Comparison in result between 2 methods K-


No Back’grnd

No noBack’grnd

# Events Data

Raw Acc MC

Acc * Particle ID (muon veto or E/P < 0.95)

Backgrounds

291274 295517 Kmu3 33635 0.1053 0.1051 ±0.0002 Pipi0dk 0.0135+-0.0007

Pipi0pi0dk 0.00111+-3x10-5

1771466 1771633 pipi0 271027 0.1540 0.1530±0.0003 Ke3 9.28x10-5+-6x10-6

Correction due to pion decaying after LKR (0.993)

293394 297397 Kmu3 30331 0.1053 0.1020 ± 0.0002 Pipi0dk 0.0125+-0.0007

Pipi0pi0dk 0.0011+-3.3x10-5

1773866 1804720 pipi0 276147 0.1539 0.1530 ±0.0003 Pipi0dk 0.014+-0.0062

Kmu3 0.00330+-7.6x10-5

Br Result

Br Ratio

Br(Kmu3)+ 0.0346 ± 0.0003

Br(Kmu3)- 0.0345 ± 0.0003

Br(Kmu3)+ 0.0350 ± 0.0002

Br(Kmu3)- 0.0350 ± 0.0002

• The error statistical and includes:– Data sample– MC statistics– Errors in particle ID efficiency

• No systematic errors have been included– I must still propagate the errors due to the background– And the “not decay after lkr error”


LKR HAC

Muon Veto

My own pi0 mass cut as a function of energy (right now using Michals – possible source for decrease of events in data? Have to check, will check changes in data base / compact why events have decreased since dec meeting)

The Br as a function of momentum

When kmu3 is a source of background – see the effect of the kmu3 Br from PDG used in the analysis (higher order todo)

Vertex in data/mc problem

The factor to correct for particles not decaying after lkr in MC – need to checked if a small correction should be applied to LKR/HAC case –for the region between lkr and hac … for the pipi0dk and pipi0pi0dk backgrounds. Right now not corrected.

Re-measure the correction for decay not simulated in MC as a check.

Check sensitivity to vertex and pt cuts

My to do – and questions


Pion ID efficiency E/P < 0.95 (common to both analysis

methods) • Pion ID efficiency

calculated using pipi0 sample from min bias run.

• Kinematic cuts (as in my selection)– Muon veto

requirement to reject muons

– But have a tighter Kaon mass cut for this sample (0.485, 0.505 GeV).

• Event Timing and Fiducial cuts as in Kmu3 Br analysis



anne dabrowski northwestern university collaboration meeting 22 nd february 2005 update kmu3...

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