| {User} or {User.Name} |
Display name of the user who issued the query. For example, this value can be used to query content of the managed property Author. |
| {User.Email} |
Email address of the user who issued the query. For example, this value can be used to query content of the managed property WorkEmail. |
| {User.SID} |
SID of the user who issued the query. |
| {User.LCID} |
Numeric value of locale as defined in the profile of the user who issued the query. |
| {User.PreferredContentLanguage} |
Language as specified as Preferred Content Language in the profile of the user who issued the query. |
| {User.PreferredDisplayLanguage} |
Language as specified as Preferred Display Language in the profile of the user who issued the query. |
| {User.<property>} |
Any property from the user profile of the user who issued the query — for example, SPS-Interests, including custom properties |
Ref: http://technet.microsoft.com/en-us/library/jj683123(v=office.15).aspx
