Analysis of a D* + Decay Path and Natural Line Width

1. Analysis of a D*+ Decay Path and Natural Line Width Jeff Rodriguez Mike Sokoloff Rolf Andreassen Carol Fabby

2. Importance of particle physics and general physics research • Spin off technologies- Internet, Computers, Kings Island • Answer some simple questions • How did the universe come to be? • Where is all the anti-matter? • Why do objects have mass? • What is dark matter and dark energy? • Particles, Strings, and Dimensions? • The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful. If nature were not beautiful, it would not be worth knowing, and if nature were not worth knowing, life would not be worth living.- Henri Poincaré. Jeff Rodriguez

3. Importance of particle physics and general physics research ; • advanced software for information-sharing (the World Wide Web), distributed grid-computing and radiation-exposure simulations for space and medical technologies. • accelerators for medical diagnosis, therapies, food-treatment, micro electronics production and energy-generation; radiofrequency power generation • high-field magnets for medical imaging; • radiation and imaging detectors for use in pharmaceutical, biological and materials sciences, medical and security equipment; • Novel ‘bionic’ implants A new type of active pixel sensor developed for the LHC has many applications but the most exciting are retinal implants which have the potential to restore partial sight to the blind. • Hilger Crystals in London had to mass-produce fast-response scintillator crystals for the BaBar experiment, which then allowed the company to supply its products at a price that was attractive to manufacturers of medical imaging equipment. Jeff Rodriguez

4. BABAR Experiment • The goal of the experiment is to study the violation of charge and parity (CP) symmetry in the decays of B mesons. This violation manifests itself as different behaviour between particles and anti-particles and is the first step to explain the absence of anti-particles in everyday life. • B-factories confirm matter-antimatter asymmetry; leads to 2008 Nobel Prize in Physics http://www-public.slac.stanford.edu/babar/Nobel2008.htm Jeff Rodriguez

5. What is so important about this study? • CP violation? • If CP symmetry holds, the decay rate of B mesons and their antiparticles should be equal. Analysis of secondary particles produced in the BaBar detector showed this was not the case – in the summer of 2002, definitive results were published based on the analysis of 87 million B/B meson-pair events, clearly showing the decay rates were not equal. Consistent results were found by the Belle experiment at the KEK laboratory in Japan. • What about this study? Jeff Rodriguez

6. Particle Data Group D* (2010)+ , D0, and ∆m values D*(2010)+ 2008 +/- 3 MeV D* (2010)+ Width 96 +/-4(stat) +/-22 (syst) keV D0 1864.84 +/- .17 MeV ∆m= m D*+(2010) = m D0145.421 +/- .01 MeV D* (2010)+ Decay Modes Mode Fraction(Γi/Γ) D0π+ (67.7 +/- 0.5)% D+ π0 (30.7 +/- 0.5)% D+γ (1.6 +/- 0.4)% Jeff Rodriguez

7. Particle Data Group Why is fraction>100%? D0 Decay Modes Inclusive Modes Fraction(Γi/Γ) Scale factor K- anything (54.7 +/- 2.8)% S=1.3 K0 anything +K0 anything (47 +/- 4)% K+ anything (3.4 +/- 0.4)% More….. The D0 and D0 bar are the mass eigenstates of the D0 meson( due to mixing). Need to determine proper description of decay mode Jeff Rodriguez

8. CLEO Detector @Cornell (CESR) • Although CLEO ran mainly near the Υ(4S) to study B mesons, it was also competitive with experiments designed to study charm hadrons. CLEO was the first experiment to measure the doubly Cabibbo suppressed decay D0→ K+π-,[99] and CLEO performed Dalitz analyses of D0,+ in several decay modes.[100][101][102][103][104][105] • CLEO studied the D*(2010)+, making the first measurement of its width and the most precise measurement of the D*-D0 mass difference.[106] CLEO-c made many of the most accurate measurements of D meson branching ratios in inclusive channels,[107][108] μ+νμ, [109] semileptonic decays,[110][111] and hadronic decays. [112][113][114] • These branching fractions are important inputs to B meson measurements at BaBar and Belle. CLEO first observed the purely leptonic decay Ds+→μ+ν,[115] which provided an experimental measure of the decay constant fDs. • CLEO-c made the most precise measurements of fD+[116] and fDs.[117] These decay constants are in turn a key input to the interpretation of other measurements, such as B mixing.[118] Jeff Rodriguez

9. Decay being studied (for D*+ natural line width): D*+ D0π+ D0 K-π+π0 π+ π+ π0 D0 Signal Side These particles reach layers of the detector D*+ K- e + e - Tag Side Note-Decay image altered from Carol Fabby’s analysis Jeff Rodriguez

10. D0 mass vs ∆m Jeff Rodriguez

11. D0 mass distribution • .1461>∆m>.1447 What happened to stat boxes? Jeff Rodriguez

12. D0 mass Region Selections • Central Signal Region 1.835-1.855 GeV/c2 • Upper Signal Band 1.865-1.885 GeV/c2 • Lower Signal Band 1.835-1.855 GeV/c2 • Upper Side Band 1.940-1.960 GeV/c2 • Lower Side Band 1.760-1.780 GeV/c2 Jeff Rodriguez

13. D0 Mass Cuts on ∆m Jeff Rodriguez

14. Tag SVT and Drift Chamber selection • Make requirements on number of hits to have well measured tracks: Pion SVT OK Kaon SVT OK Slow Pion SVT OK • For high quality tracks, good track resolution and to remove background: Kaon DCH Hits > 20 Pion DCH Hits > 20 Jeff Rodriguez

15. TagSVT and nDch Cuts Jeff Rodriguez

16. Cabibbo Favored vs. Doubly Cabibbo Suppressed“Right Sign vs. Wrong Sign” 0.3% favored 99.7% favored Jeff Rodriguez

17. Cabibbo Favored vs. Doubly Cabibbo Suppressed“Right Sign vs. Wrong Sign” Jeff Rodriguez

18. π CF(+/+) vs CDS(+/-) Jeff Rodriguez

19. Something here about how the calorimeter picks up 2 photons as a means of determining the detection of pi 0 and thus the probability that a particle detected is a pi 0 • Also something about chi2 analysis Jeff Rodriguez

20. Plots of π0 Chi2 probability function Jeff Rodriguez

21. Probability of π0 Chi2 >0.2 Jeff Rodriguez

22. Dalitz plot explanation K- (m1) D0(M) π+(m2) π0 (m3) Jeff Rodriguez

23. Dalitz plot explanation (cont.) http://en.wikipedia.org/wiki/Dalitz_plot http://pdg.lbl.gov/2009/reviews/rpp2009-rev-kinematics.pdf Dalitz description pge4 Don’t forget invariant mass description Jeff Rodriguez

24. Need extra code to clean up outsides of plot Dalitz Plots of Signal region Jeff Rodriguez

25. Dalitz Cuts New code will be needed to determine regions of high cross product m2 rather than using ranges Jeff Rodriguez

26. Kinematic Limits 3-body decay • http://en.wikipedia.org/wiki/Particle_decay • http://pdg.lbl.gov/2009/reviews/rpp2009-rev-kinematics.pdf • Put in equations here and description of 3 particle decay • Try and calculate angle in lab vs cm and compare? Jeff Rodriguez

27. P and Energy (lab and CM) Jeff Rodriguez

28. Center of Mass Momentum Cut Jeff Rodriguez

29. Effect of all cuts on ∆m Jeff Rodriguez

30. MC Truth Matching • • Not just verifying the decay mode exists • • Goal: find best match for D0 and check the mode • • “Top down” approach • – Find the best match for the D*+, πs, D0 (verify D*+ D0πs) • – Find best match for the D0 daughters • – From prev. step you know you have the D0 • – Make the separate categories for signal mode and bkg Zach Huard Presentation on Truth Jeff Rodriguez

31. Example Event - Event 0 /data/huard/05Jul10_MC_MWDstStudy/SP*.root" Jeff Rodriguez

32. Event info Jeff Rodriguez