The track formed by the matched boxes, a.k.a. tracklets, is used in the second stage association.

Tracklet Association Tracker: An End-to-End Learning-based Association Approach for Multi-Object Tracking, 2018

tracklet is a short track between frames

https://stackoverflow.com/questions/55512548/whats-the-difference-between-track-and-tracklet-in-tracking

A fragment of the track followed by a moving object,

https://en.wiktionary.org/wiki/tracklet

Tracklet은 짧은 구간에서의 경로

https://m.blog.naver.com/sw_maestro/221032791075