7.1. Particles

Particles in basf2 are created from reconstructed dataobjects: Tracks, tracking vertices (V0s), ECLClusters, and KLMClusters. The Particle class, provides a unified way to treat different objects at a high level interpreting them as physical particles. All of the Particle s in an event that fall within certain criteria are collected into ParticleList s.

The Belle II physics performance group already has several predefined ParticleList s. To use them you need to use functions described in the standard particle lists.

• 7.1.1. Standard Particles
  • Default final-state particle list builder functions
  • Not (yet) recommended final-state particle list builder functions
  • Other functions available

Creation of new particle lists by combination of particles is essential part of almost any analysis job. The syntax used during this procedure is the DecayString and is described below:

• 7.1.2. DecayString
  • Particles and Decays
  • Selection
  • Grammar for custom MCMatching
    • Marker of unspecified particle
    • Markers for Final State Particles
    • Keywords
    • Arrows

It is often desirable to apply selections to ParticleList s, and events. This is done with cut strings.

• 7.1.3. Cut strings and selections