ILC - HEPHY
ILC - HEPHY
ILC - HEPHY
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Example decay tree and fit algorithm<br />
cay tree: KinematicTree<br />
be created,<br />
Invalid production<br />
vertex<br />
Invalid decay<br />
vertex<br />
B 0<br />
s<br />
B 0 Decay Vertex<br />
s<br />
J/ Ψ<br />
Φ<br />
(Previous state)<br />
− + −<br />
µ + µ Κ Κ<br />
Constraints<br />
(Present State)<br />
The kinematic fit: LMS minimization<br />
χ 2 minimization with the set of additional constraints H y ref<br />
0,<br />
linearized (first order Taylor expansion) around some given point<br />
H y exp<br />
<br />
yy exp<br />
H y exp<br />
D yd 0<br />
y<br />
D: matrix of derivatives, one line per constraint equation<br />
(n_equations x n_parameters)<br />
d: vector of values of constraints<br />
Function to minimize with respect to y ref<br />
, :<br />
2 y ref yV y<br />
1<br />
y<br />
ref<br />
y<br />
T<br />
2 <br />
T<br />
D yd min<br />
y exp<br />
Decay tree example for B 0 s → J/ψΦ → µ+ µ − K + K − .<br />
Winfried Mitaroff <strong>HEPHY</strong> Projektbericht, 19. November 2007
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