Transferring information retrieval (IR) models from a high-resource language (typically English) to other languages in a zero-shot fashion has become a widely adopted approach. In this work, we show that the effectiveness of zero-shot rankers diminishes when queries and documents are present in different languages. Motivated by this, we propose to train ranking models on artificially code-switched data instead, which we generate by utilizing bilingual lexicons. To this end, we experiment with lexicons induced from (1) cross-lingual word embeddings and (2) parallel Wikipedia page titles. We useResearch goal: How does the robustness of neural ranking models trained on synthetic code-switched data compare to models trained on original monolingual data when evaluated on adversarial cross-lingual benchmarks like XLM-R's zero-shot retrieval tasks?Autonomous synthesis report generated by Assignee Research. Tribunal consensus score: 8.1/10.