Interactions of light gravitinos

Abstract

In models of spontaneously broken supersymmetry, certain light gravitino processes are governed by the coupling of its Goldstino components. The rules for constructing SUSY and gauge invariant actions involving the Goldstino couplings to matter and gauge fields are presented. The explicit operator construction is found to be at variance with some previously reported claims. A phenomenological consequence arising from light gravitino interactions in supernova is reexamined and scrutinized.

Phenomenology of a leptonic goldstino and invisible Higgs boson decays

“…Soon after, it was realized [2] that interpreting the goldstino as one of the Standard Model (SM) neutrinos was not allowed by the low-energy theorems of supersymmetry, which prescribe a much softer infrared behaviour of the goldstino amplitudes with respect to the neutrino ones. Many years later, it was also noticed that, already at the lowest order in the derivative expansion, the bilinear goldstino couplings to the SM fields are more general than the universal coupling to the energy-momentum tensor [3,4,5], and explicit examples were produced [6] in superstring models with D-branes.…”

Nonlinear realization of supersymmetry and superconformal symmetry

“…This is reminiscent of the situation which occurs in the coupling of gauge fields with nonlinearly realized SUSY. In that case, if one demands that the gauge field transforms as a nonlinear SUSY standard realization, then its gauge transformation is nonstandard [10]. Note, however, that neither the special conformal nor the dilatation symmetries are spontaneously broken in this realization.…”

“…A field transforming as Λ µ (ξ,ξ)∂ µ under nonlinear SUSY is said to carry the standard realization [9]- [10].…”

Gauging nonlinear supersymmetry

“…Additional discussion of these couplings in the global SUSY case can be found in Ref. [15]. There is another useful oneform basis in which to express the derivatives and gauge fields [14].…”

“…The fully covariant derivatives for the scalar, S x , and fermion, x and _ x , matter fields have the explicit form It proves convenient to catalog the terms in the effective Lagranian, L eff , by an expansion in the number of Goldstino/gravitino fields which appear after the Goldstino and gravitino fields are set to zero in the fully covariant derivatives and in the vierbein [15]. This is tantamount to counting the number of factors of the fermionic Mauer-Cartan one-forms in each expression.…”