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Search for Direct CP Violation in 3-body Cabibbo Suppressed D 0 Decays

Investigating direct CP violation in multimode D0 decays, especially in Cabibbo-suppressed modes, as a potential probe beyond Standard Model predictions. Using Dalitz plot analyses for separate D0 and D0bar decays, aiming to identify evidence of non-SM processes.

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Search for Direct CP Violation in 3-body Cabibbo Suppressed D 0 Decays

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  1. Search for Direct CP Violation in 3-body Cabibbo Suppressed D0 Decays Kalanand Mishra, G. Mancinelli, B. T. Meadows, M. D. Sokoloff University of Cincinnati • Motivation • Strategy • Summary and outlook Charm AWG 08/17/2006

  2. CP Violation in D0 Decay CPV expected to be small in the charm sector SM predictions O(0.1%) Look for particle Û anti-particle rate differences CPV > 1% will be a strong evidence for non-SM processes - - Where f is: p+p-p0 [π, …] and K+K-p0[K*K, π0 , …].Decays to these final states are Cabibbo-suppressed, enhancing the possibility that interference with non-SM amplitudes could produce direct CP violation. University of Cincinnati

  3. Why 3-body CS modes ? • The best hope for SM predicted CP violation in Charm decays is in CS modes. The prediction for CF decays are too small. • 3-body decays permit the measurement of phase differences which are required to create direct CP violation in the interference between SM and non-SM processes. • These are relatively high statistics modes (45000 D0/D0barπππ0 & 6800 D0/D0barKKπ0 events). • Since we can normalize measurements relative to the whole phase space (Dalitz plot), the dependence on πs tagging efficiency is negligible. University of Cincinnati

  4. direct CPV Strategy • need interference between diagrams with different strong (i) and weak phases (i) : • Perform separate Dalitz plot analyses of D0π-π+π0 (K-K+π0) and D0barπ+π-π0 (K+K-π0). • Models have already been established in both cases that provide good description of data. University of Cincinnati

  5. What is Known ? • CLEO measure ACP in D0π-π+π0 mode ACP = 0.01 + 0.05 • No ACP measurements available for D0K-K+π0 • Other analysis are under way to measure CP asymmetry in D0K-K+, π-π+ modes Measure the difference between the integral of the coherent sum of all amplitudes across the DP for D0 and D0bar, divided by the area of the DP. +0.07 -0.05 • ACP(K+K-) = 0.014 ± 0.010 • ACP(π+π-) = 0.013 ± 0.012 • ACP(π0π0) = 0.00 ± 0.05 • ACP(K+K-π+π-) = -0.08 ± 0.07 PDG 2006  University of Cincinnati

  6. Dalitz Plot Fit Results: π-π+π0 BAD 1174 University of Cincinnati

  7. Dalitz Plot Fit Results: K-K+π0 BAD 1502 University of Cincinnati

  8. What we have looked at ? • Our sensitivity to observe CP asymmetry is higher in the D0π-π+π0 decay because of the higher statistics in this mode. • However, I have started with D0K-K+π0 mode since recently I have been working on this Dalitz plot analysis. • Start by looking at the distribution of moments of the cosine of the helicity angle in data for both D0 and D0bar events. • Then perform separate Dalitz plot fit for CP conjugate events. University of Cincinnati

  9. Moments of cosH [K+π0] D0 __ D0 University of Cincinnati

  10. Moments of cosH [K-π0] D0 __ D0 University of Cincinnati

  11. Moments of cosH [K-K+] D0 __ D0 University of Cincinnati

  12. Separate DP Fits Amplitude Phase f0(980)0.65 ± 0.140.48 ± 0.13 0.9103.2 ± 13.483.0 ± 18.1 0.9 f2’(1525)1.12 ± 0.210.85 ± 0.20 0.9-38.8 ± 8.5-45.0 ± 10.6 0.5 (1020)0.74 ± 0.020.73 ± 0.020.3-17.7 ± 10.3-21.0 ± 12.6 0.2 K*-(892)0.64 ± 0.020.65 ± 0.020.3-30.5 ± 3.5-40.6 ± 3.3 2.1 K*+(1410)0.64 ± 0.601.09 ± 0.570.5120.6 ± 36.7115.5 ± 20.5 0.1 K*-(1410)2.91 ± 0.452.94 ± 0.530.0184.1 ± 9.8159.6 ± 8.4 1.9 K+π0 SW4.50 ± 1.393.08 ± 1.110.863.1 ± 8.9100.4 ± 11.4 2.6 K-π0 SW4.92 ± 0.684.12 ± 0.860.7154.0 ± 14.8114.7 ± 16.2 1.8 D0 D0bar D0 D0bar # SD # SD University of Cincinnati

  13. Separate DP Fits Amplitude Phase K*-(892)0.63 ± 0.020.66 ± 0.021.1-30.8 ± 3.3-41.1 ± 3.2 2.2 K*+(1410)0.30 ± 0.311.04 ± 0.301.7 87.6 ± 70.5100.7 ± 16.0 0.3 K*-(1410)2.80 ± 0.272.72 ± 0.280.2182.8 ± 6.9168.8 ± 6.1 1.5 K+π0 SW4.85 ± 0.743.65 ± 0.581.366.9 ± 7.286.3 ± 10.3 1.6 K-π0 SW4.78 ± 0.633.59 ± 0.571.4160.0 ± 8.6 123.6 ± 10.5 2.7 D0 D0bar D0 D0bar # SD # SD Parameters for CP eigen states are fixed to the ones obtained from the combined fit. University of Cincinnati

  14. Summary • After performing D0π-π+π0, K-K+π0 Dalitz plot analysis, we have started looking into CP asymmetries in the conjugate decays. • We will keep documenting (BAD 1531) as we move along. • We aim for a preliminary result for DPF 2006. University of Cincinnati

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