An MBTA driver reported that a Green Line trolley passenger yelled at her, called her a racial slur, and punched her in the arm before running away Sunday afternoon, according to Transit Police. The passenger, described as a man in his 50s wearing a black coat and pushing a carriage full of computer parts, assaulted the 42-year-old driver just after the trolley stopped at the Fenway Station on the D branch of the Green Line at about 3:10 p.m., police said in a report. After the incident, the man ran from the train toward Landmark Center, the report said. If police find the man, the MBTA plans to ask a judge to ban him from using the T, agency spokesman Joe Pesaturo said. The T driver declined medical treatment.