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Exclusive D s Semileptonic decays using kinematic fitting.

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Presentation on theme: "Exclusive D s Semileptonic decays using kinematic fitting."— Presentation transcript:

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 

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/or 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

7 Exclusive Ds semileptonic decays7 Invariant mass of D s tag 

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    

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]

10 Exclusive Ds semileptonic decays10 Efficiencies dependences  e Effic.Err. w/ PID8.570.17 w/o 1st PID8.60.17 w/o both8.610.17 w/o 2nd PID8.580.39 K* e Effic.Err. w/ PID8.140.57 w/o PID on K8.340.58

11 Exclusive Ds semileptonic decays11 Next … Will remove the PID on the K in K*(Kπ). Run on Generic MC. Run on data.


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