To my knowledge, there aren't specific naming convention for branches. However, it's wise to use names that are easy identifiable, like tasknames or abbreviation for work. We are using JIRA for tasks and use the JIRA ID when naming the branch.
We are using JIRA -Ticket ID and ALM / Rally - Story ID / Defect ID as the branch name. It helps to track the rules changed after the branch has been merged to the main rulesets by doing content search.