Open string field theory is considered as a tool for deriving the effective action for the massless or tachyonic fields living on D-branes. Some simple calculations are performed in open bosonic string field theory which validate this approach. The level truncation method is used to calculate successive approximations to the quartic terms φ4, (AAμ) 2 and [Aμ, Aν ] 2 for the zero momentum tachyo...

We continue our study of effective field theory via homotopy transfer L ? $L_\infty$ -algebras, and apply it to tree-level non-Wilsonian actions the kind discussed by Sen in which modes integrated out are comparable mass that kept. focus on construction for string states at fixed levels particular weakly constrained double theory. With these examples mind, we discuss closed toroidal backgrounds...