Ke2 and Kmu2 Mengkai Shieh Northwestern University

Pisa M. Shieh, Northwestern University Physics Motivation Measure Br Ratio of Ke2 more precisely Measure Br Ratio of Ke2 more precisely Test Lepton Universality Test Lepton Universality

Pisa M. Shieh, Northwestern University Data Sample Eventually, full run based on Ke2 and Kmu2 triggers Eventually, full run based on Ke2 and Kmu2 triggers Today, only Monte Carlo and data based on minimum bias run (only Q1 trigger) so no trigger issues. Today, only Monte Carlo and data based on minimum bias run (only Q1 trigger) so no trigger issues.

Pisa M. Shieh, Northwestern University Initial Cuts 1 track 1 track 1 cluster 1 cluster e/p > 0.9 e/p > 0.9 HAC Energy < 10 GeV HAC Energy < 10 GeV LKR Energy > 2 GeV LKR Energy > 2 GeV 2 GeV< track p < 80 GeV 2 GeV< track p < 80 GeV Track and cluster correspond Track and cluster correspond Fiducial cuts 12cm < r < 110cm Fiducial cuts 12cm < r < 110cm 5 sigma timing cut 5 sigma timing cut

Pisa M. Shieh, Northwestern University Tuning of Cuts Look at Monte Carlo results Look at Monte Carlo results Maximize signal events Maximize signal events Minimize background Minimize background K->pi0ev(Br 5%)K->pi0ev(Br 5%) K->pipi0(Br 21%)K->pipi0(Br 21%)

Pisa M. Shieh, Northwestern University Monte Carlo Results Ke2 (signal), Br: 1.55 X 10-5 Ke2 (signal), Br: 1.55 X 10-5 Ke3 (background), Br: 0.05 Ke3 (background), Br: 0.05 Kpipi0 (background), Br: 0.21 Kpipi0 (background), Br: 0.21 Kmu2 (normalization) Kmu2 (normalization)

Pisa M. Shieh, Northwestern University Ke2, Ke3 MC Vertex Ke2 acceptance relatively flat, Ke3 drops sharply. Ke2 acceptance relatively flat, Ke3 drops sharply. Can use vertex to make a good cut. Can use vertex to make a good cut.

Pisa M. Shieh, Northwestern University Ke2, Ke3 MC p T Can cut for pt > 0.2 Can cut for pt > 0.2

Pisa M. Shieh, Northwestern University Ke2, Ke3 MC M fake Mfake calculated with electron mass Mfake calculated with electron mass Can cut for Mfake > 0.45, Mfake 0.45, Mfake < 0.525

Pisa M. Shieh, Northwestern University Ke2, Ke3 MC p e Can cut on electron p Can cut on electron p Ke3 gone for p > 52 GeV Ke3 gone for p > 52 GeV

Pisa M. Shieh, Northwestern University 2-Dimensional Cuts Look at 2-Dim acceptance plots to determine cuts for maximizing signal events while effectively cutting out the background. Look at 2-Dim acceptance plots to determine cuts for maximizing signal events while effectively cutting out the background.

Pisa M. Shieh, Northwestern University Acc vert vs Acc pt

Pisa M. Shieh, Northwestern University Acc vert vs Acc Mfake

Pisa M. Shieh, Northwestern University Kpipi0 MC p T

Pisa M. Shieh, Northwestern University Kpipi0 MC M fake

Pisa M. Shieh, Northwestern University Kpipi0 MC p pi

Pisa M. Shieh, Northwestern University Data Tuning Tuning Minimum bias runsMinimum bias runs 25 Aug Vus run 25 Aug Vus run Runs 15746, Runs 15746, Intensity 1/8, trigger Q1/4. Intensity 1/8, trigger Q1/4. Total of 1860 bursts. Total of 1860 bursts. Future Ke2, Kmu2 triggers Future Ke2, Kmu2 triggers

Pisa M. Shieh, Northwestern University Extra Cuts (vertex>2000||pt>.2)&&mfake>0.45 &&mfake 2000||pt>.2)&&mfake>0.45 &&mfake<0.525&&pt<.25 Acc for Ke2 =.511 Acc for Ke2 =.511 Acc for Ke3 = 0 Acc for Ke3 = 0

Pisa M. Shieh, Northwestern University Data

Pisa M. Shieh, Northwestern University Data

Pisa M. Shieh, Northwestern University Data/Conclusion flux and trigger efficiency cancel flux and trigger efficiency cancel We get N e and   from the data and acceptances from the Monte Carlo. We get N e and   from the data and acceptances from the Monte Carlo. Left and right sides are not equal, therefore, we still have background that we need to eliminate. Left and right sides are not equal, therefore, we still have background that we need to eliminate. If we use the more rigid cuts instead of the looser box cut for vertex and pt (vertex>2000 && pt>.2), we get the following values: N_e=10, acc_e=.296, and above equation becomes: If we use the more rigid cuts instead of the looser box cut for vertex and pt (vertex>2000 && pt>.2), we get the following values: N_e=10, acc_e=.296, and above equation becomes: right side=.96x10^-5, left side=1.7x10^-5 May need to investigate pipi0 more to make a better selection. May need to investigate pipi0 more to make a better selection.