Related Experiment Video
Updated: Apr 6, 2026

Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
New Fermionic Soft Theorems for Supergravity Amplitudes
Wei-Ming Chen1, Yu-Tin Huang1,2, Congkao Wen3
1Department of Physics and Astronomy, National Taiwan University, Taipei 10617, Taiwan, Republic of China.
Abstract:
Soft limits of a massless S matrix are known to reflect the symmetries of the theory. In particular, for theories with Goldstone bosons, the double-soft limit of scalars reveals the coset structure of the vacuum manifold. In this Letter, we propose that such universal double-soft behavior is not only true for scalars, but also for spin-1/2 particles in four dimensions and fermions in three dimensions. We first consider the Akulov-Volkov theory and demonstrate that the double-soft limit of Goldstinos yields the supersymmetry algebra. More surprisingly, we also find that amplitudes in 4≤N≤8 supergravity theories in four dimensions as well as N=16 supergravity in three dimensions behave universally in the double-soft-fermion limit, analogous to the scalar ones. The validity of the new soft theorems at loop level is also studied. The results for supergravity are beyond what is implied by supersymmetry Ward identities and may impose nontrivial constraints on the possible counterterms for supergravity theories.
Related Concept Videos
The Principle of Superposition and the Gravitational Field
Superposition Theorem
Symmetry in Maxwell's Equations
Differential Form of Maxwell's Equations
Fundamental Theorem of Algebra
Superposition Theorem for AC Circuits
The principle of superposition stipulates that the output of a linear circuit with several concurrent inputs is equivalent to the...

