R ² LLMs: Retrieval and Ranking with LLMs

Generative Large Language Models (LLMs) like GPT, Gemini, and Llama are transforming Information Retrieval, enabling new and more effective approaches to document retrieval and ranking. The switch from the previous generation pre-trained language models backbones (e.g., BERT, T5) to the new generative LLMs backbones has required the field to adapt training processes; it also has provided unprecedented capabilities and opportunities, stimulating research into zero-shot approaches, reasoning approaches, reinforcement learning based training, and multilingual and multimodal applications. This tutorial will provide a structured overview of LLM-based retrievers and rankers, covering fundamental architectures, training paradigms, real-world deployment considerations, and open challenges and research directions.