What is the shortest known GM level OTB game to end with checkmate? What is the shortest known on the board game played between GM rated players that ended with a checkmate? "Shortest" does not mean the game has to be very short. 

Note: Edited this question twice clarifying some ambiguity.
Keres-Arlamowski 1950, comes very close

[FEN ""]
[Event "Szczawno Zdroj"]
[Date "1950"]
[Result "1-0"]
[White "Paul Keres"]
[Black "Edward Arlamowski"]

1. e4 c6 2.Nc3 d5 3.Nf3 dxe4 4.Nxe4 Nf6 5.Qe2 Nbd7 6.Nd6# 1-0


I heard Mr Arlamovski was an IM at the time - but given Keres' level, and the fact that there were many fewer IM's back then - probably puts the game into the GM level category.