BCFT and OSFT moduli: an exact perturbative comparison
Starting from the pseudo-${\cal B}_0$ gauge solution for marginal deformations in OSFT, we analytically compute the relation between the perturbative deformation parameter $\tildeλ$ in the solution and the BCFT marginal parameter $λ$, up to fifth order, by evaluating the Ellwood invariants. We observe that the microscopic reason why $\tildeλ$ and $λ$ are different is that the OSFT propagator renormalizes contact term divergences differently from the contour deformation used in BCFT
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