# Bonn 2010 – wissenschaftliches Programm

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# HK: Fachverband Physik der Hadronen und Kerne

## HK 65: Hadronenstruktur und -spektroskopie XI

### HK 65.6: Vortrag

### Freitag, 19. März 2010, 15:30–15:45, HG IV

**Vertex and kinematic fitting for Panda** — •Vishwajeet Jha and James Ritman — IKP, Forschungszentrum, Jülich, Germany

The efficient reconstruction of the primary and secondary vertices is crucial for many topics in the PANDA physics program. The vertex position of a set of tracks can be determined by varying the track parameters such that the total error is minimized under the condition that the tracks pass through a common vertex point. In addition, the kinematic information of various particles in a particular decay chain can be used as constraints, leading to an improvement in the momentum and mass resolution of the reconstructed particles.

The algorithms based on kinematic constraints for the vertex fitting have been implemented in the Pandaroot software package.
The method includes the constraints by the Lagarange multipliers and it uses an iterative χ^{2} minimization procedure for vertex fitting. The performance of the vertex fitter has been tested by reconstructing the short lived decay particles *D*_{s}^{±} mesons (*c*τ = 147 µ *m*) and Λ baryons (*c*τ = 7.89 *cm*), using simulated events from the reactions *p* p → *D*_{s}^{±} *D*_{s}^{*}(2317) ^{∓} and *p* p → Λ Λ, respectively. These decay particles have been reconstructed from the tracks of their daughter particles. In addition to the vertex fit, the possibility to include other kinematic constraints such as mass constraint, total momentum constraint, total energy constraint, four momentum constraints etc. are being developed and tested.