update kmu3 branching ratio measurement

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– DCH resolution correction to MC

– Energy scale 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– 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.


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


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)– Min PT of 0.15 GeV– 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

Method 1:Method 1:


Correction Factor due to pion not

decaying in MC after LKR

• IN MC 6.4m decay volume, particle decay not simulated (LKr to MUV)

• Apply a correction to MC acceptance of pipi0, momentum dependent

• Inefficiency of 0.2% for MUV-ID taken into account

Method 1:Method 1:


The efficiency of pion decay in pipi0 in data and MC (max z is zlkr in MC)

Probability of a pion NOT decaying between LKr and MUV

Muon Veto ID

Acceptance of signal and normalisation

channel Raw Acceptance from MC

Acceptance * particle ID

Final acceptance(including correction factor due to decay between lkr and muon veto)

kmu3 0.1052±0.0002 0.1047±0.0002(muon veto ID)

0.1047±0.0002No correction needed

Pipi0 0.1541±0.0001(when the pion has not decayed)

0.1531±0.0001(E/P < 0.95)(excluding μ rejection efficiency)

0.1521±0.0001Correction due to MC decay bin by bin

Integrated value including μ -ID inefficiency overall correction 6.5‰

Method 1:Method 1:


Normalization

Signal

Sources of Background to kmu3+

Source of

Background

Particle ID used

RAW MC acceptance no particle ID

Acceptance*particle ID

Acceptance*

Particle ID

*correction

Background(Accbk*Br_bk)/(AccS*BR_sign

al)

Comments

Pipi0dk(when

pion decays)

Muon veto ID (2.05+-0.05)x10-4

(2.04+-0.05)x10-4

(1.26±0.04)x10-2

No correction

pipi0pi0dk

Muon veto ID (2.20+-0.07)x10-4

(2.19+-0.01)x10-4

(1.11±0.05)x10-3

No correction

Pipi0(when

pion doesn’t decay)

Real punch through correction

0±7x10-4 (without real punch though corr )

No events in 2M mc events ..

Pipi0pi0(when


Real punch through correction

0±7x10-4 (without real punch though corr)

No events in 2M mc events ..

Method 1:Method 1:


Ask teresa

Sources of Background to pipi0+

Source ofBackground

Particle ID used

Raw Acceptance

Acc*Particle ID

Need for a correction to MC decay?

Background(Accbk*Br_bk)/(AccS*BR_signal)

pipi0dk E/P < 0.95!MUV

(2.26+0.02)x10-3

(#pipi0dk/gen#pipi0 when


(1.7+-0.1)x10-5

Yes(1.7+-0.1)x10-5

(1.15+-0.08)x10-4

kmu3 E/P < 0.95!MUV

(3.27+0.04)x10-3

(1.3+-0.2)x10-6

(1.3+-0.1)x10-5

ke3 E/P < 0.95!MUV

(2.33±0.03)x10-4

(6.7±0.4)x10-5

(1.01±0.06)x10-5

pipi0pi0dk E/P < 0.95!MUV

0

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 HAC

Method 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


Recall Method 1 eff at 0.998

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:


Probability of pion NOT decaying between the LKR and the HAC

Method 2:Method 2:


LKR & HAC muon ID

Acceptance of signal and normalisation

channel Acceptance from MC

Acceptance * particle ID

Final acceptance(including correction factor due to decay between lkr and hac)

kmu3 0.1052±0.0002 0.1019±0.0002(lkr & hac muon ID)

0.1019±0.0002No correction factor needed

Pipi0 0.1562±0.0001No μ -ID

0.1553±0.0001(E/P < 0.95)

0.1553±0.0001No correction factor needed

Method 2:Method 2:


Signal

Normalization

Sources of Background to kmu3+Source of Backgrou

nd

Particle ID used Raw MC accepta

nce

MC acceptance* particle ID

MC Acc* particle ID * decay factor

Background(Accbk*Br_bk)

/(AccS*BR_sig

nal)

Decay factor for MC acceptance included?

Comments

pipi0dk Muon ID (lkr hac)

(2.05+-0.05)x10-4

(1.97+-0.04)x10-4

(1.24+-0.03)x10-2

no

pipi0pi0dk

Muon ID (lkr hac)

(2.20+-0.07)x10-4

(2.13+-0.07)x10-4

(1.11+-0.05)x10-3

no

Pipi0_ib Pion mis-id as muon using lkr & hac

(2.44+- 0.05)x10-3

1.6+-0.3x10-4

(1.32+-0.0 8)x10-05

pipi0 Pion mis-id as muon using lkr & hac

Calculate small number of pions that decay -> muon id

[if pi decays:acc0x10-6]

[if pi not decay: acc 1.1x10-5

(7.4+-0.4)x10-4

Sample split, and small amount that would have decayed get muon ID

No events in 2M mc events …

pipi0pi0 Pion mis-id as muon using lkr and hac

Is this correct to include decay factor?

0. 0. 0. 0±7x10-4 Sample split, and small amount that would have decayed get muon ID

No events in 2M mc events …

Method 2:Method 2:

Sources of Background to pipi0+

Source of Background

Particle ID

used

Raw MC Acceptance

Raw Mc acceptance* particle ID

Background(Accbk*Br_bk)/(AccS*BR_signal)

Comments

kmu3 E/P < 0.95

(3.27 +-0.04)x10-3

(3.27+-0.04) x10-3

(3.26+-0.08)x10-3

ke3 E/P < 0.95

(2.34 +-0.01)x10-3

(6.7+-0.4)x10-5

(9.9 +-0.6)x10-5

pipi0pi0 E/P < 0.95

0 2M events

Method 2:Method 2:


LKR HAC

Muon Veto

Comparison in result between 2 methods K+

N0 afterBackgroun

d subtracted

N0 withoutBackground

subtracted

Raw # Events Data

Raw Acc MC

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

Acc * Particle ID * MC decay correction if necessary

Backgrounds(Accbk*Br_bk)/(AccS*BR_signal)

Kmu3

526,635 533,861 55,905 0.1052±0.0002

0.1047±0.0002

0.1047±0.0002

Pipi0dk (1.26±0.04)x10-2

Pipi0pi0dk (1.11±0.05)x10-3

pipi0 3209,079 3209,815 488,334 0.1542±0.0001

0.1532±0.0001

0.1522±0.0001

Ke3 (1.01±0.06)x10-5Pipi0dk (1.15+-

0.08)x10-4Kmu3 (1.3+-0.1)x10-5

Kmu3

528,655 536,215 54,623 0.1051 ±0.0002

0.1018 ± 0.0002

0.1018 ± 0.0002

Pipi0dk (1.31+-0.07)x10-2

Pipi0pi0dk (1.13+-0.06)x10-3Pipi0 (7.4+-0.4)x10-4Pipi0_ib (1.32+-0.0

8)x10-05

pipi0 3193,700 3204,410 497,464 0.1562 ±0.0001

0.1553±0.0001

0.1553±0.0001

Kmu3 (3.25+-0.07)x10-3

Ke3 (9.9 +-0.6)x10-5

Br Result

Br Ratio

Br(Kmu3)+ 0.0347 ± 0.0003

Br(Kmu3)-

Br(Kmu3)+ 0.0354 ± 0.0002

Br(Kmu3)-

• 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 corrected … but must check logic

● Check sensitivity to vertex and pt cuts

My to do – and questions


update kmu3 branching ratio measurement

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