Emergent strings, duality and weak coupling limits for two-form fields

A bstract We systematically analyse weak coupling limits for 2-form tensor fields in the presence of gravity. Such are significant testing various versions Weak Gravity and Swampland Distance Conjectures, more broadly, phenomenon emergence. The 2-forms correspond to certain infinite-distance moduli space string compactifications, where asymptotically tensionless, solitonic strings arise. These identified as weakly coupled fundamental a dual frame, which makes idea emergence manifest. Concretely we first consider six-dimensional compactifications F-theory, arising tensionless play role heterotic strings. As main part this work, infinite distance Type IIB on K3 surfaces, show that describe strings, again surfaces. By contrast analogous M-theory found an F-theory limit extra dimension emerges rather than comment extensions our findings four-dimensional compactifications.