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Résumé |
> This talk is dedicated to recent double-copy constructions that unify massless tree-level
amplitudes in a variety of perturbative string theories. All the polarization dependence in
gauge- and gravity amplitudes of type-I, type-II, bosonic and heterotic string theories is
proposed to enter via field-theory building blocks with a known Lagrangian origin. The second
double-copy component of massless string amplitudes involves moduli-space integrals over
punctured sphere and disk worldsheets whose low-energy expansion introduces multiple zeta
values. At each order in the inverse string tension alpha’, the coefficients of highest
transcendental weight turn out to be universal across the above perturbative string theories.
These phenomena have not been explained by the known string dualities and are hoped to
reflect a deeper principle in the theory of quantum gravity. |
