# Reconstruction efficiency for events.

## Efficiency definition

### Good candidate:

A good candidate is a MCParticle in the event that satisfies the following requirements.

• is a charged pion(PID = 211 or PID = -211)
• perp of the start vertex < 10
• prep of the end vertex > 100

### Good event:

A good event is a event with no less than 3 good MCParticle candidates in it.

### Reconstructed event

A reconstructed is good event with all the good MCParticle candidates reconstructed. The definition of Reconstructed MCParticle can be found in previous section.

### Efficiency

Efficiency is defined as: efficiency = #(Reconstructed events)/#(Good events)

Arbor CEPCv4