Symplectic structure in open string field theory II: Sliding lump
Vinícius Bernardes, Theodore Erler, Atakan Hilmi Fırat
TL;DR
This work develops a concrete Hamiltonian perspective on open string field theory by deriving a new phase-space symplectic structure for boosted solitonic lumps. The authors obtain a mass formula ${m = \dfrac{1}{g^2} \mathrm{Tr}_{Q\sigma}[(i J^{01} \Psi)(i p_1 \Psi)]}$ and demonstrate, via an analytic D0-lump, that the resulting D-brane tension matches the on-shell action through an $L_\infty$ coalgebra framework. They resolve divergences inherent in twist-field-based constructions by a divergence-free sigmoid built from a lightlike boson, and compute the lump mass explicitly as ${m = \dfrac{Z_{\mathrm{D0}}}{\mathrm{vol}(X^0)} \dfrac{1}{2\pi^2 g^2}}$, confirming the expected D0-brane tension. The final general boosted-solution analysis shows the mass is equivalent to the on-shell action expansion around a boost-invariant vacuum, establishing a robust link between Hamiltonian observables and on-shell dynamics in open SFT.
Abstract
We use a new formula for symplectic structure to compute the momentum of an analytic lump solution moving at constant velocity in Witten's open string field theory. The computation gives a new way to determine the D-brane tension in string field theory. Using homotopy algebra technology, we prove that this tension must agree with the value implied by the on-shell action.
