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Status of the measurement of the main K L branching ratios

Status of the measurement of the main K L branching ratios. M. Antonelli, M. Dreucci, E. De Lucia, C. Gatti, M. Moulson, T. Spadaro. CP meeting 02-2003. Tag bias. Ks  p + p - selection: Rt<10cm ;|z|<20 cm |m-m K |<5 MeV; |p*-p* K |<10 MeV. e. 63%.

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Status of the measurement of the main K L branching ratios

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  1. Status of the measurement of the main KLbranching ratios M. Antonelli, M. Dreucci, E. De Lucia, C. Gatti, M. Moulson, T. Spadaro CP meeting 02-2003

  2. Tag bias Ks p+p-selection: Rt<10cm ;|z|<20 cm |m-mK|<5 MeV; |p*-p*K|<10 MeV e 63% • Main bias is expected from trigger • require trigger from ks pions: • clusters connected to fired trigger sector • no other cluster in “ks sectors” (avoid overlaps) • no splitted pion tracks (T2CL asso. quality) • + ks direction far from beam line (cos(q)>0.9) 39% 25% 20%

  3. e KLtag 63% standard 39% Ks trigger 25% + overlaps 20% + tracks q. Ks dir. Tag bias: MC results Relative KS +- efficiency for various KL process KL p0p0p0 KL All KL p+p-p0 in FV KL en out FV Crash included KL mn +/- 1%

  4. Tracking + Vertex efficiency Double tag method ( from KL p+p- analysis) Conditional efficiency N2/N1 from data KS p+p- x swlen dist Tag definition: sliding cuts on DIST and SWLEN

  5. dist (cm) swlen (cm) Rt (cm) Rt (cm)

  6. emc edt Data-MC comparison (2002 data) e DATA MC P*(MeV) 1.06 in 2000

  7. emc edt Data-MC comparison (2002 data) e DATA MC Rt(cm)

  8. emc edt Vertex efficiency (2002 data) e DATA MC Rt(cm)

  9. Signal counting: Kinematics Several variables tried: Pmiss-Emiss with mass hypothesis (pm,mp) giving min |Pmi.-Emi.| Fit to expected MC distributions 3 parameters c2norm=1.5 DATA MC KL p+p- Fixed to expected contribution

  10. Signals separation Correlation matrix: ke3 km3 3p 1. -0.1 -0.02 1. -0.03 1. KL mn KL en KL p+p-p0 Pmiss-Emiss (MeV)

  11. Signal counting: Kinematics DATA MC Pmiss-Emiss (MeV)

  12. Preliminary results: Total number of tag: 11707500 (L~ 78pb-1) run# 25*** KL en KL mn KL p+p-p0 C=ei/etot (tag) 0.995 1.01 0.992 dC (1-C)/2 <e> FV 0.255 <e> track+vertex 0.508 0.485 0.338 Fit Results: 581245 396713 129445 errors* 2963 2521 1420 Branching 0.3840.002 0.2710.002 0.1320.002 PDG 0.3880.003 0.2720.002 0.1260.002(s=1.7) *Dominated by MC statistcs (~6.5 pb-1)

  13. O order result ready: almost unbiased KL tag tracking efficiency ~ agreement with MC shapes not that bad results in agreement with PDG Conclusions To do list: Include KL3p0 (sum Branching ratios to 1 up to 10-3) Checks on KLtag bias: compare data MC agreement for different KL tags* compare with KS-> 2p0 Track + Vertex : use new vertex routine some mc-dt disagreement for resolutions (probably fine with new MC ) Increase MC statistic (statistical error, tag bias studies, tracking eff. Studies…..) * Agreement at <1%(MC stat.) level (from morning studies)

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