Multiloop f3 amplitudes from bosonic string theory Original Research Article

We show how the multiloop amplitudes of f3 theory (in the world-line formulation of Schmidt and Schubert_ are recovered from the N-tachyon (h + 1)-loop amplitude in bosonic string theory in the α′ → 0 limit, if one keeps the tachyon coupling constant fixed. In this limit the integral over string moduli space receives contributions only from those corners where the world-sheet resembles a f3 particle diagram. Technical issues involved are a proper choice of local world-sheet coordinates, needed to take the string amplitudes off-shell, and a formal procedure for introducing a free mass parameter M2 instead of the tachyonic value −4/α′.