2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/137824A covariant calculus for the construction of effective string theories is developed. Effective string theory, describing quantum string-like excitations in arbitrary dimension, has in the past been constructed using the principles of conformal field theory, but not in a systematic way. Using the freedom of choice of field definition, a particular field definition is made in a systematic way to allow an explicit construction of effective string theories with manifest exact conformal symmetry. The impossibility of a manifestly invariant description of the Polchinski-Strominger Lagrangian is demonstrated and its meaning is explained.13 pagesHigh Energy Physics - TheoryHigh Energy Physics - Latticetext