The Scrum Guide says the following:
The Product Owner is also accountable for effective Product Backlog management, which includes:
- Developing and explicitly communicating the Product Goal;
- Creating and clearly communicating Product Backlog items;
- Ordering Product Backlog items; and,
- Ensuring that the Product Backlog is transparent, visible and understood.
The Product Owner may do the above work or may delegate the responsibility to others. Regardless, the Product Owner remains accountable.
What does this "to others" mean? That the Product Owner can delegate the responsibility to the Scrum Master?