1. Exclusive D s Semileptonic decays using kinematic fitting

2. Exclusive Ds semileptonic decays2 Analysis Techniques e+ e- (1 -- ) D s +* (D s + ) +...D s - (D s -* )      e + and K* 0 (K +  - ) e + n SIGNAL SIDE TAGGED SIDE: + CC Event       K s            K + K - )  -  +  -  - K*K*(K s K -  +  - )  - 

3. Exclusive Ds semileptonic decays3 Analysis Techniques Define the beam constrained mass: Cut “loose” on M bc then look at the invariant mass. We do NOT require one candidate per event based on “best” M bc since M bc and the invariant mass are correlated. Evaluate missing mass-squared (MM 2 ) on the signal side:

4. Exclusive Ds semileptonic decays4 Selection criteria Track Quality Cuts: Hit fraction > 0.5 Good fit |d0|<0.5cm and |Z0|<5.0cm |cosθ| < 0.93 |p| >0.04 GeV Particle ID Both dE/dX & RICH PID if |p| > 0.7GeV, dE/dX PID if |p| < 0.7       PID for the 1st and/or 2 nd kaon. |  Mass-PDG|<0.02 GeV        PID for Pion and kaon. |    Mass-PDG|<0.100 GeV e  electron ID. |p| > 0.2GeV. F RICH ≥ 0.8

5. Exclusive Ds semileptonic decays5 Kinematical constraints Mass of the tag is constrained to the D S mass Total of 7 constraints 4 Missing variables in the fit (Energy and Momentum of the ).  2 is then determined for both  -tag or  -he hypotheses for any legitimate photon candidates.

6. Exclusive Ds semileptonic decays6 MM 2 resolution improvements Fitted Not fitted Ds +    e + nu K + p - mass [0.7761,0.9761] GeV Ds +   e + nu K + K - mass [1.010,1.030] GeV Signal MC

7. Exclusive Ds semileptonic decays7 Invariant mass of D s tag  KsK-KsK- hp-hp-hp- Inv Mass (GeV) f r -  r- Data K * K * from K s K - p + p - p+p-p-p+p-p-

8. Exclusive Ds semileptonic decays8 MM 2 for D s +   e + Ds +   e + nu K + K - mass [1.010,1.030] GeV MM 2 [GeV 2 ] m [GeV] Inv mass     Data

9. Exclusive Ds semileptonic decays9 MM 2 for D s +  K* 0 e + Ds +    e + nu K + p - mass [0.7761,0.9761] GeV Inv mass  MM 2 [GeV 2 ]m [GeV] Data

10. Exclusive Ds semileptonic decays10 Next … Will remove the PID on the K in K*(Kπ). Get effect on effeciencies. Get the branching fractions.

11. Exclusive Ds semileptonic decays11 Generic MC(1)

12. Exclusive Ds semileptonic decays12 Generic MC(2)

13. Exclusive Ds semileptonic decays13 Generic MC(3)