1. Anne Dabrowski 26 February 2004 1 Semileptonic Analysis from Low Intensity Run Anne Dabrowski Northwestern University NA48 Collaboration Meeting 26 February 2004

2. Anne Dabrowski 26 February 2004 2 Want to measure V us using K ± → e ± νπ 0 and K ± → μ ± νπ 0 events Measuring V us involves: –Br (K ± →e ± νπ 0 ) and Br (K ± →μ ± νπ 0 ) Goal measure ratio: –e ± νπ 0 / (π ± π 0 + μ ± ν + π ± π ± π ± +…….) Goal measure ratio: –μ ± νπ 0 / (π ± π 0 + μ ± ν + π ± π ± π ± + …….) –Extract the Form Factors Step for NOW: –Study e ± νπ 0 π ± π 0 μ ± νπ 0 –Want small backgrounds, high acceptance –Systematic error contribution less than 1/1000 –Good understanding of the MC and the DATA

3. Anne Dabrowski 26 February 2004 3 Outline of Talk Data Quality Check Trigger Efficiency Selection Acceptance Backgrounds Ongoing work –Radiative corrections –MC tuning

4. Anne Dabrowski 26 February 2004 4 Proton Intensity for Special Run Data from Special run 15746 & 15747 1800 bursts. Low intensity (I/8) Trigger: Q1/4 or 1 Trackloose/100 + something else. Data for this talk is non-reprocessed data

5. Anne Dabrowski 26 February 2004 5 DATA Quality issues NOTE: difference between track and cluster time –We do NOT apply cut on the difference between track and cluster time varies with E/P Due to the difference between the track and cluster (associated to the track) time varies with E/P as seen here. E/P

6. Anne Dabrowski 26 February 2004 6 The difference between Track and Cluster time for each channel Mean ~ 0.6 Rms ~ 1.3 Mean ~ 1.5 Rms ~ 0.5 Mean ~ -0.2 Rms ~ 1.6 e ± νπ 0 events π ± π 0 events μ ± π 0 ν events

7. Anne Dabrowski 26 February 2004 7 Cluster times among themselves fine Plot of the difference in the time of the 2 gammas Mean ~ -0.4 Rms ~ 0.5 Mean ~ -0.5 Rms ~ 0.5 Mean ~ -0.4 Rms ~ 0.5 e ± νπ 0 events π ± π 0 events μ ± π 0 ν events

8. Anne Dabrowski 26 February 2004 8 Timing a function of EOP Since timing varies as a function of EOP (energy in LKR of cluster), we do not cut on the difference between track and cluster time for clusters associated to tracks. We would have to have a separate timing cut for each channel –This would cause bias Needs investigation, not believe to be such a problem right now, because of the low intensity and low accidental activity.

9. Anne Dabrowski 26 February 2004 9 Trigger Efficiency Trigger: Q1/4 or 1 Trackloose/100 + something else Data for this talk on non-reprocessed data π ± π 0 (99.90+0.02-0.01)% e ± νπ 0 (99.85 +0.06-0.06) % μ ± νπ 0 (99.88+0.04-0.04) %

10. Anne Dabrowski 26 February 2004 10 Current Selection in Summary Data from Special run 15746 & 15747 1800 bursts. Low intensity (I/8) Trigger: Q1/4 or 1 Trackloose/100 + something else Data for this talk is non-reprocesed data MC used is CMC003 version released on 2 February 2004 π±π0π±π0 e ± νπ 0 μ ± νπ 0 Number good events55688711116148840 Acceptance (using cmc003 release 2 February 2004) (25.68±0.19) %(13.54±0.01)%(14.09±0.01)% Trigger Efficiency (99.90+0.02- 0.01)% (99.85+0.06- 0.06)% (99.877+0.041 -0.04)%

11. Anne Dabrowski 26 February 2004 11 Selection single trackWITH a single π 0Classify all single track events WITH a single π 0, as either: –π ± π 0 –e ± νπ 0 –μ ± νπ 0 events. –Future work will include e ± νπ 0 γ and μ ± νπ 0 γ –Future it is hoped to implement a particle decay ID probability for each Kaon event in your detector. Preferably only kinematic cuts : –Avoid cuts in Dalitz plane (extract form factors) –Similarly, avoid cuts on COM energy (sensitive radioactive corrections) –Treat event classification of selection and normalization as close as possible to cancel systematic inefficiencies.

12. Anne Dabrowski 26 February 2004 12 Treatment of Tracks Cuts: –1 track events (not ghost track) –Hodoscope Track in time window of event (-15.5 19.5) ns –Track Time min max (-17.5, 19.5) ns –Standard fiducial volume of every sub detector (see Appendix) –Track Quality > 0.7 –CDA from dx/dz and dy/dz CDA cut < 1.5 Min Max z vertex (-2500 8000.) cm Min Max X vertex (-1.8 1.8) cm Min Max y vertex (-1.8 1.8) cm

13. Anne Dabrowski 26 February 2004 13 Treatment of Gammas Use Michal Szleper’s LKR energy scale (see talk M. Szleper) Look for a π 0 candidate using charged vertex. –In the case of π ± π 0 Loop over all in time “good” gammas to find a good pizero mass –In the case of e ± νπ 0 and μ ± νπ 0 2Select only 2 in time “good” gammas –Good gamma is: Energy (1.5, 65.) GeV Sep distance > 10 cm Evt time – Gamma time (-2.4, -0.3) ns Timing between themselves (-1.5, 1.5) ns Cut on pizero mass (0.128, 0.142) GeV

14. Anne Dabrowski 26 February 2004 14 π±π0π±π0 e ± νπ 0 Scale in y arbitrary π±π0π±π0 e ± νπ 0 μ±π0ν μ±π0ν μ±π0ν μ±π0ν Exploit differences in kinematics So we have a event with a track and a π 0. What next?

15. Anne Dabrowski 26 February 2004 15 COM energy of pizero Visible energy of event μ±π0ν μ±π0ν e ± νπ 0 π±π0π±π0

16. Anne Dabrowski 26 February 2004 16 Neutrino mass Constraint π ± π 0 MC e ± π 0 ν MC μ ± π 0 ν MC Assuming π mass e mass μmass The neutrino mass squared is calculated with the assumption of the mass of the particle associated the that track. Assuming 60GeV of the Parent Kaon. Mis-ID of track mass gives skewed distribution to neutrino mass.

17. Anne Dabrowski 26 February 2004 17 PT vs P plane Invariant mass of Track and Pizero π±π0π±π0 e ± νπ 0 or μ ± π 0 ν π±π0π±π0 μ±π0ν μ±π0ν e±π0ν e±π0ν

18. Anne Dabrowski 26 February 2004 18 Check 1. IS Combination of 1Track and π 0 a π ± π 0 event ? K ± → π ± π 0 is most constrained channel (no missing energy). My selection algorithm checks for these events first. Cuts: –Mass kaon (M kaon -0.2, M kaon +0.2) GeV –Momentum (10, 50) GeV (min cut of 10 if for efficient MUV status) –PT Track (0.0, 0.215) GeV –PT π 0 (0.0, 0.22) GeV –Nu mass min max (-0.0025, 0.001) GeV –Energy of π 0 (10, 50) GeV Particle ID –EOP > 9.5 candidate Ke3 event (not considered as a π ± π 0 candidate) –MUV Status candidate Kmu3 event (not considered as a π ± π 0 candidate )

19. Anne Dabrowski 26 February 2004 19 Note: Particle ID Cuts EOP and MUV status checkWe choose to use particle ID (EOP and MUV status check) –Although this introduces the need for an efficiency study into these cuts, without these cuts, you get a 2% contamination (mis-identification) of Ke3 and Kmu3 events as pipi0. –Possibility to implement the neural network in future.

20. Anne Dabrowski 26 February 2004 20 Check 2 Is event e ± νπ 0 or μ ± νπ 0 candidate ? IF the event fails the π ± π 0 event ID → then candidate for e ± νπ 0 or μ ± νπ 0 selection check Cuts Ke3 P min max (5.,40.) GeV Pt Track min max (0.01,0.2) GeV PT π 0 min max (0.01,0.23) GeV Nu mass min max (-0.012,0.012) GeV Energy of π 0 > 10. GeV COM energy π 0 < 0.27 GeV COM energy Track < 0.22GeV Cuts Kmu3 P min max (10.,40.) GeV (min cut of 10 if for efficient MUV status) Pt Track min max (0.02,0.2) GeV PT π 0 min max (0.02,0.22) GeV Nu mass min max (-0.01,0.01) GeV Energy of π 0 min max (10.,40) GeV COM energy π 0 < 0.24 GeV COM energy Track < 0.23GeV Kaon mass < 0.45 GeV

21. Anne Dabrowski 26 February 2004 21 DATA / MC comparison momentum of Track π±π0π±π0 e ± νπ 0 μ±π0ν μ±π0ν Check quality of low momentum events CMC003 mc rad cor on MC dots in above plot Ratio: Data/MC

22. Anne Dabrowski 26 February 2004 22 DATA/MC comparison energy of π 0 π±π0π±π0 e ± νπ 0 μ±π0ν μ±π0ν CMC003 mc rad cor on MC dots in above plot Ratio: Data/MC

23. Anne Dabrowski 26 February 2004 23 DATA/MC comparison PT of π 0 π±π0π±π0 e ± νπ 0 μ±π0ν μ±π0ν CMC003 mc rad cor on MC dots in above plot Ratio: Data/MC

24. Anne Dabrowski 26 February 2004 24 DATA/MC comparison PT of Track π±π0π±π0 e ± νπ 0 μ±π0ν μ±π0ν CMC003 mc rad cor on MC dots in above plot Ratio: Data/MC

25. Anne Dabrowski 26 February 2004 25 DATA/MC comparison COM energy π 0 π±π0π±π0 e ± νπ 0 μ±π0ν μ±π0ν

26. Anne Dabrowski 26 February 2004 26 Naïve Background Contributions: π±π0 events coming through e±νπ 0 ~ 2.1x10 -3 e±νπ 0 and μ ± νπ 0 events coming through π±π 0 ~ 4.7x10 -4 π±π 0 events coming through μ ± νπ 0 ~ 2.9x10 -3 Other channels checked, and not a significant source of background e ± νπ 0 γ and μ±νπ 0 γ channels are sources of background but are missing from MC.

27. Anne Dabrowski 26 February 2004 27 Acceptance for channels as a function of PT π ± π 0 e ± νπ 0 π±π0π±π0 μ±π0ν μ±π0ν π±π0π±π0 μ ± νπ 0 Acceptance (using cmc003 release 2 February 2004) (25.68±0.19) %(13.54±0.01)%(14.09±0.01)%

28. Anne Dabrowski 26 February 2004 28 Radiative Corrections Ke3 1/2 π±π0π±π0 μ±π0ν μ±π0ν e±π0ν e±π0ν Radiative Corrections have been applied by Stoyan. Based on treatment by Ginsberg. Plot shows the effect of radiative corrections to the mass of the e±νπ0 More work will be done to check radiative corrections by V Bytev arXiv:hep-ph/0210049 …. in the cmc. Need to generate e±νπ0 γ separately too.

29. Anne Dabrowski 26 February 2004 29 Radiative corrections Ke3 2/2 The existing calculations were E.S.Ginsberg and T.Becherrawy in the late 60’s Their results for corrections to the decay rate, Dalitz plot, pion and positron spectra disagree, in some places quite sharply; for example Ginsberg’s correction to the decay rate is.0.45% while that of Becherrawy is.2% (corresponding to corrections to the total width of 0.45 and 2 respectively). Work will be done with Rosner’s Student at U-Chicago and Earl Swallow to help understand and implement the corrections.

30. Anne Dabrowski 26 February 2004 30 Radiative Corrections Kmu3 Radiative Corrections have been coded by Mengkei at Northwestern, and are being debugged. They are the corrections of Ginsberg. Phys Rev D Vol1 Number 1 1 Jan 1970 p220 The Effect of radiative corrections to Kmu3 less than that of Ke3.

31. Anne Dabrowski 26 February 2004 31 TO do list MC tune up of beam –Great improvement from Dmitri with the introduction of new turtle description of Turtle –Northwestern will help tune beam (shift at DCH1 in y known problem of cmc tuning group) Check MC / DATA energy scale in LKR Implement μ ± νπ 0 radiative corrections Carefully re-examine new papers out of e±νπ0 radiative corrections – to understand treatment e ± νπ 0 γ and μ ± νπ 0 γ