Lets say, a company lay off some of its eligible workforce while retaining the current pension plan. What are the accounting steps for this process? What is the difference between us gaap and ifrs? Can you tell me a key word for this process so I can do my research in the right direction ? I am doing a research paper.

You will have to research GAAP and IFRS yourself after all this is your research

The usual accounting treatment is to identify and quantify the liability. As this is a complex process it may be that an actuarial determination may be required. Once the liability is known a provision or a reserve will be created charging current year earnings, but a further question exists, a provision should already have existed for these liabilities