Exclusive D s Semileptonic decays using kinematic fitting

Exclusive Ds Semileptonic decays using kinematic

fitting

Exclusive Ds semileptonic decays 2

Analysis Techniquese+ e- (1--)

Ds+* (Ds

+) + ...Ds-(Ds

-*)

e+ and K*0(K+-) e+

SIGNAL SIDE

TAGGED SIDE:

+ CC Event

Ks

K+K-)-

+--

K*K*(KsK-+-)-


Analysis Techniques• Define the beam constrained mass:

• Cut “loose” on Mbc then look at the invariant mass. We do NOT require one candidate per event based on “best” Mbc since Mbc and the invariant mass are correlated.

• Evaluate missing mass-squared (MM2) on the signal side:


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 2nd kaon. | Mass-PDG|<0.02

GeV

PID for Pion and kaon. | Mass-PDG|<0.100

GeV

e

electron ID.|p| > 0.2GeV.FRICH ≥ 0.8


Kinematical constraints

•

•

•

• • Mass of the tag is constrained to the DS 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.

2 2 2 2

*

(2.1121) (1.9683) (2.1121) (1.9683)

4* 4*Ds beam Ds beambeam beam

E E or E EE E

*S S

beam D D2E =E +E

*SS

DDM -M =143.6 MeV


MM2 resolution improvements Fitted

Not fitted

Ds+ e+ nu K+- mass [0.7761,0.9761] GeV

Ds+ e+ nuK+K- mass [1.010,1.030] GeV

Signal

MC


Invariant mass of Ds tag

KsK-

Inv Mass (GeV)

-

Data

K*K* from KsK--


MM2 for Ds+ e+

Ds+ e+ nuK+K- mass [1.010,1.030] GeV

MM2 [GeV2] m [GeV]

Inv mass

Data


MM2 for Ds+K*0 e+

Ds+ e+ nu K+- mass [0.7761,0.9761] GeV

Inv mass

MM2 [GeV2] m [GeV]

Data


Next …

• Will remove the PID on the K in K*(Kπ).

• Get effect on effeciencies.

• Get the branching fractions.


Generic MC(1)


Generic MC(2)


Generic MC(3)

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Exclusive D s Semileptonic decays using kinematic fitting