Browsing by Subject "Classical Theories of Gravity"

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    Amplitudes from Coulomb to Kerr-Taub-NUT
    (2022-05-10) Emond, William T; Huang, Yu-tin; Kol, Uri; Moynihan, Nathan; O’Connell, Donal
    Electric-magnetic duality, the Newman-Janis shift, and the double copy all act by elementary operations on three-point amplitudes. At the same time, they generate a network of interesting classical solutions spanning from the Coulomb charge via the dyon to the Kerr-Taub-NUT spacetime. We identify the amplitudes corresponding to each of these solutions, working to all orders in spin, but to leading perturbative order. We confirm that the amplitudes double-copy when the solutions are related by the classical double copy. Along the way we show that the Kerr-Taub-NUT solution corresponds to a gravitational electric-magnetic duality rotation acting on the Kerr solution, again to all orders in spin, and demonstrate that the asymptotic charges also transform simply under our operations.
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    New dynamical degrees of freedom from invertible transformations
    (2023-07-19) Jiroušek, Pavel; Shimada, Keigo; Vikman, Alexander; Yamaguchi, Masahide
    Abstract We show that invertible transformations of dynamical variables can change the number of dynamical degrees of freedom. Moreover, even in cases when the number of dynamical degrees of freedom remains unchanged, the resulting dynamics can be essentially different from the one of the system prior to transformation. After giving concrete examples in point particle cases, we discuss changes in dynamics due to invertible disformal transformations of the metric in gravitational theories.