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Progress in D 0 K s K + K - and Dº  K s K analysis Results from an exercise Dalitz fit for D +  K + K - 

Progress in D 0 K s K + K - and Dº  K s K analysis Results from an exercise Dalitz fit for D +  K + K -  + D 0 K s K + K - Dalitz plot Detached sample, no tagging 2900 runs (Each point is doubly entered) f(1020) D 0 K s K + K - Dalitz plot, tagged sample

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Progress in D 0 K s K + K - and Dº  K s K analysis Results from an exercise Dalitz fit for D +  K + K - 

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  1. Progress in D0Ks K+ K- and Dº Ks K analysis • Results from an exercise Dalitz fit for D+ K+K- + Amir Rahimi/FOCUS

  2. D0Ks K+ K- Dalitz plot • Detached sample, no tagging • 2900 runs (Each point is doubly entered) f(1020) Amir Rahimi/FOCUS

  3. D0Ks K+ K- Dalitz plot, tagged sample D*++D0  K0barK+ K- Look for resonances in either K+ K- or K0bar K+ and vice versa. Detached sample with the D* tagging. Determine the strangeness of the Ks by tagging the charm of the D0 Decay trees for this D0 decay mode, showing some possible resonances which couple u and d quarks to s quarks: a0(980) a0(980)? f0(980)? f0(980) f(1020)? f(1020) Amir Rahimi/FOCUS

  4. f0(980) simulation from Rodney Green’s thesis. y axis is M2(K-pi+) and x axis is M2(K- K+). How is a0+ (980) simulated in MCFocus? • Simulated the following decay and its c.c. • D*+ D0p+ • a0+ (980) K- •  Ks K+ •  p+ p - • The Dalitz plot is populated according to a0+ (980) decay. Amir Rahimi/FOCUS

  5. Revisit DºKs K with higher statistics Recall we fit four signal yields to a function of 3 variables + + • N = total yield •  = Charm-anti-Charm asymmetry (fragmentation dynamics) + The ² of this fit of 3 parameters with 4 dof is a test of hypothesis that CP is conserved which model is based on. Amir Rahimi/FOCUS

  6. Example of the fit with higher statistics obs pred N 21.1 25.4 D*+K+ N 61.0 56.5 D*+K- N 35.1 40.1 D*-K+ N 26.7 18.0 D*-K- D0K+ D0K- obs pred N 136 136 D*+K+ N 330 330 D*+K- D0BarK- N 320 320 D0BarK+ D*-K+ ² =0.0011 for 1 dof CL=99% N 132 132 D*-K- Detached sample (no out of target cut): N=140 =0.17 fK+=.31 (too Low!) • This was in October ² =3.13 for 1 dof CL=7.71% What’s up with the widths?! N=919 =0.015 fK+=.292 (lower!) • This is NOW Amir Rahimi/FOCUS

  7. Summary • We have looked at D0Ks K+ K- Dalitz plot with 2900 runs • D* tagging virtually eliminates the background • There is a clear indication of f(1020) resonance as well as some indications of both f0(980) and a0(980) resonances. • It appears that MCFocus simulates a0(980) with the correct matrix element • We are in the process of learning how to fit for a0(980) • We repeated our CPV studies of DºKs K with higher statistics • A significant improvement in ² • The charm anti-charm asymmetry is around =0.015; more reasonable compared to =0.17 • We are seeing fK+=0.292 (+/- 0.023), the PDG value is fK+= 0.439 (+/- 0.1) Amir Rahimi/FOCUS

  8. D+ K+K- + sample (provided by JEW): • We pick a “dirty” sample for this study • First we do do a log likelihood fit to the combined sample from low and high side bands; this is our background fit • Then we do a log likelihood fit to the signal region • The asymmetry in K*(890) lobes in signal suggests interference with K*(1430) A practice Dalitz fit with D+ K+K- + f(1020) No Zemach nodes K*(1430) f(1020) K*(890) high s.b. Low s.b. signal K*(890) No Zemach nodes Amir Rahimi/FOCUS

  9. Likelihood profiles for the combined low and side bands D+ K+K- +background fit • For the background fit intensity function we pick two Breit-Wigners for f and K*(890) and a flat background • We fit for f and K*(890) amplitudes, fixing the flat background at unity f K*(890) Low side band overlays of data and the background intensity function(the fit quality with the high side band is similar to this): K*(890) f K+  + K-  + K-K+ Amir Rahimi/FOCUS

  10. We fix the parameters in the background probability density function to the values we obtained from our fit to the background. • For the signal region we pick • three Breit-Wigners for f, K*(890) and K*(1430) • Zemach factors for f and K*(890) • two complex phases and two amplitudes. • Do a log likelihood fit to the signal probability density function Clean sample D+ K+K- +signal fit f K*(1430) Log likelihood profiles: phase The results match the likelihood profiles that we obtain using a clean D+ K+K- + sample in which we do not fit for the background (the arrows indicate the clean sample minimums) Amp. Amir Rahimi/FOCUS

  11. D+ K+K- + Dalitz projections • Putting it all together, we overlay the Dalitz squared mass projections of the combined probability density function and the data • The overlays match reasonably well f lobes K*(890) f lobes f K*(890) lobes K-  + K-K+ K+  + Amir Rahimi/FOCUS

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