作者: Hidenori Sonoda , Barton Zwiebach
DOI: 10.1016/0550-3213(90)90086-S
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摘要: Abstract It is shown that symmetric modular invariant quadratic differentials with factorization properties allow the construction of covariant closed string field theory counterterms restore BRST invariance to loop amplitudes. Off-shell scattering amplitudes are constructed in terms hermitian vertices and propagators; they manifestly factorizable all channels, unitary orders perturbation theory. We discuss Strebel on any punctured surface.