readme: ---
  license: mit
  ---
  
  This model has been pretrained on MS MARCO corpus and then finetuned on MS MARCO training data with implicit distributionally robust optimization (iDRO), following the approach described in the paper **COCO-DR: Combating Distribution Shifts in Zero-Shot Dense Retrieval with Contrastive and Distributionally Robust Learning**. The associated GitHub repository is available here https://github.com/OpenMatch/COCO-DR.
  
  This model is trained with BERT-large as the backbone with 335M hyperparameters.