Solution date format
1. Edit the related Item Template.
2. Add the ArticleStartDate to the ManagedPropertyMapping. For a clean example I removed all mappings besides Title and ArticleStartDate in the code below.
3. Create a variable for the ArticleStartDate column.
4. To be able to format the date we need to create a new variable of the type Date.
5. Us the code below to display the ArticleStartDate with the required format.