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Two Cut Analysis Optimization

Daniel J. Cruz Dept. of Physics and Astronomy Texas A&M University. Two Cut Analysis Optimization. Presentation. Overview Utilizing Cuts Actual Experiment Results Summary. 2. Overview. Utilize cuts in physics to better analyze data

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Two Cut Analysis Optimization

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  1. Daniel J. Cruz Dept. of Physics and Astronomy Texas A&M University Two Cut Analysis Optimization

  2. Presentation • Overview • Utilizing Cuts • Actual Experiment • Results • Summary 2

  3. Overview • Utilize cuts in physics to better analyze data • Show that care needs to be taken when making cuts (cannot make them blindly) • Sometimes two cuts AREN’T better than one cut 3

  4. Utilizing Cuts 4

  5. One Cut Analysis • Cut away part of data • Stick with most useful • Free to move cut selection (in this case, 200 GeV) 5

  6. Two Cut Analysis • Cut away part of data, then separate rest in two cuts • Cut A is original cut, cut B is new cut within original • Makes data more manageable • Can move both cuts, or keep one cut (A) static while moving other cut (B) 6

  7. Actual Experiment 7

  8. Expected Cross Sections • We look for 95% confidence limit on expected cross section, σproduction • Utilize cuts technique to optimize σ95 • Used modified Fortran Limiting Calculator program, coded by Dr. Joel Walker of Sam Houston State University 8

  9. Experiment • Data taken from Eunsin Lee’s Ph.D. thesis at Texas A&M, Phys. Rev. Lett. 104, 011801 (2010) • Binned values were used, as well as fitted values • Graph provided by Chris Davis (modified graph in slides 5 and 6) 9

  10. Background • Fitted background • Used an exponential curve • Red dots are fit, black dots are actual data 10

  11. Acceptance • Fitted acceptance • Used a Gaussian curve • Red dots are fit, black dots are actual data 11

  12. One Cut Experiment • Red dots are actual data • Black dots are fitted data • Optimum is 22 fb at 240 GeV (22.5 fb at 250 GeV for fitted curve) • What about two cuts? 12

  13. Two Cut Experiment • Minimum of 21 fb at (240,36) • However, places where σ95 > 22 fb • Better than one cut in places, worse in other places! • Graph provided by Chris Davis 13

  14. Results 14

  15. How much better can you get? • Plot of cut A(250 GeV) as a function of cut B; black dotted line indicates limit at 250 GeV (22.45 fb) • By manipulating our cut B, we can optimize to 21.3 fb (achieved with cut Bat 350 GeV) 15

  16. One Cut -> Two Cut • You always (ok, most of the time) get an improvement • Have to be careful in order to maximize improvement • Shown is 2-D Minimum Limit vs. Cut A (notice that lowest limit achieved is better than 1-D) 16

  17. Summary • In MOST cases, two cuts > one cut (have to be careful, though) • Delicate in how to choose cut B (otherwise, you get result which is roughly equal to one cut) 17

  18. The Endquestions?

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