The PMI process, perform quality assurance, is in the executing process group and the quality management knowledge group.

According to the PMBOK, this activity has the following characteristics:

Inputs Tools and Templates Outputs
quality management plan, process improvement plan, quality metrics, quality control measurements, project documents quality management and control tools, quality audits, process analysis change requests, project management plan updates, project documents updates, organizational process assets updates

Perform quality assurance is described in section 8.2 of the PMBOK, 5th edition.