1. Anne Dabrowski Northwestern University Collaboration Meeting 22 nd February 2005 Update Kmu3 Branching Ratio measurement A. Dabrowski, February 22 2005

2. 2 Particle ID Test 2 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 A. Dabrowski, February 22 2005

3. ● 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 A. Dabrowski, February 22 2005

4. 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 A. Dabrowski, February 22 2005

5. Difference between Kmu3 and Pipi0 selection ● Kaon Mass (assuming pi) 0.515 GeV ● Mom (10, 40) GeV ● PT track (0.0, 0.2) GeV ● Nu mass (-0.01, 0.01) GeV 2 ● 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) ● Kaon Mass (0.475,0.515) GeV ● Mom (10, 50) GeV ● PT track < 0.215 ● Nu mass (-0.0025, 0.001) GeV 2 ● Distance between track & gammas > 35 cm ● PT pi0 < 0.220 ● E/P < 0.95 ● Use muon rejection only when the muon veto in used in the Kmu3 analysis. A. Dabrowski, February 22 2005

6. Muon ID using the Muon Veto Muon ID efficiency calculated using K μ2 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 ν 2 (-0.02;0.01) GeV 2 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: A. Dabrowski, February 22 2005

7. Muon ID signals using the LKR and HAC Cuts chosen – LKR < 1.5 GeV and HAC < 5 GeV Muon sample using K μ2 events from min bias run. Kinematic cuts – Momentum (10,40) – Banana PT vs P cut – Mass ν 2 (-0.02;0.01) GeV 2 – Muon Veto requested Event Timing and Fiducial cuts as in Kmu3 Br analysis Method 2: A. Dabrowski, February 22 2005

8. Muon ID efficiency using the LKR and HAC 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 A. Dabrowski, February 22 2005 Method 1 eff at 0.998 Corrected bi- nomial errors

9. 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: A. Dabrowski, February 22 2005 Corrected bi- nomial errors

10. ● 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.

11. LKR HAC Muon Veto Comparison in result between 2 methods K+ No Backgrou nd No no Backgrou nd # Events Data Raw Acc MC Acc * Particle ID (muon veto or E/P < 0.95) Backgrounds 525248532838Kmu3559050.10510.1049 ±0.0002 Pipi0dk 0.0133+- 0.0007 Pipi0pi0dk 0.00111+- 3x10-5 31865893186911pipi04883340.15410.1532±0.0003 Ke3 0.00010+-6x10-6 Correction due to pion decaying after LKR (0.993) 529125536558Kmu3546230.10510.1018 ± 0.0002 Pipi0dk 0.0129+- 0.0003 Pipi0pi0dk 0.00112+- 3.3x10-5 3192325324662pipi04974640.15410.1532 ±0.0003Pipi0dk 0.013+- 0.0062 Kmu3 0.00329+- 7.6x10-5 A. Dabrowski, February 22 2005

12. Muon Veto LKR HAC Comparison in result between 2 methods K- A. Dabrowski, February 22 2005 No Back’grnd No no Back’grnd # Events Data Raw Acc MC Acc * Particle ID (muon veto or E/P < 0.95) Backgrounds 291274295517Kmu3336350.10530.1051 ±0.0002 Pipi0dk 0.0135+- 0.0007 Pipi0pi0dk 0.00111+- 3x10-5 17714661771633pipi02710270.15400.1530±0.0003 Ke3 9.28x10-5+-6x10- 6 Correction due to pion decaying after LKR (0.993) 293394297397Kmu3303310.10530.1020 ± 0.0002 Pipi0dk 0.0125+- 0.0007 Pipi0pi0dk 0.0011+- 3.3x10-5 17738661804720pipi02761470.15390.1530 ±0.0003 Pipi0dk 0.014+-0.0062 Kmu3 0.00330+- 7.6x10-5

13. 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” A. Dabrowski, February 22 2005 LKR HAC Muon Veto

14. 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 A. Dabrowski, February 22 2005

15. 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 A. Dabrowski, February 22 2005 Corrected bi- nomial errors