Massive Strings from a Field Theory with Ghosts

In this Letter, we present the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msup><a:mrow><a:mi>α</a:mi></a:mrow><a:mrow><a:mo>′</a:mo></a:mrow></a:msup></a:mrow></a:math>-exact background equations of motion of the bosonic chiral string (also known as Hohm-Siegel-Zwiebach model), with the spin-two ghost fields integrated out. This is the first instance of a world sheet model in which all corrections are fully determined in a generic curved spacetime. As a concrete cross-check, we find complete agreement between all three-point and a sample of four-point tree-level scattering amplitudes computed using field theory methods and the chiral string prescription. These equations of motion provide a field theoretical shortcut to compute world sheet correlators in conventional bosonic strings (with an arbitrary number of massless and mass-level-one states) and outline a new perspective on massive resonances in string theory. Published by the American Physical Society 2024