Link background-subtraction paper

benchmark/3d_object_labels/README.md

@@ -1,6 +1,6 @@
 # CoopScenes 3D Object Labels
 
-Manually created frame-level 3D bounding boxes for CoopScenes sequences 1–4. The labels were used to derive the point-wise foreground/background reference for the paper *Beam-Wise Statistical Background Subtraction for Static Roadside LiDAR: A Cross-Sensor Benchmark Study*.
+Manually created frame-level 3D bounding boxes for CoopScenes sequences 1–4. The labels were used to derive the point-wise foreground/background reference for the paper [*Beam-Wise Statistical Background Subtraction for Static Roadside LiDAR: A Cross-Sensor Benchmark Study*](https://arxiv.org/abs/2608.14868).
 
 ## Coverage