String theory realizations of the nilpotent goldstino

Abstract

We describe in detail how the spectrum of a single anti-D3-brane in fourdimensional orientifolded IIB string models reproduces precisely the field content of a nilpotent chiral superfield with the only physical component corresponding to the fermionic goldstino. In particular we explicitly consider a single anti-D3-brane on top of an O3-plane in warped throats, induced by (2, 1) fluxes. More general systems including several antibranes and other orientifold planes are also discussed. This provides further evidence to the claim that non-linearly realized supersymmetry due to the presence of antibranes in string theory can be described by supersymmetric theories including nilpotent superfields. Implications to the KKLT and related scenarios of de Sitter moduli stabilization, to cosmology and to the structure of soft SUSY-breaking terms are briefly discussed.

D 3 ¯ $$ \overline{D3} $$ induced geometric inflation

“…In this case, the mass of the axion is given by 18) which is positive definite and consistent with our general argument in section 2.3. 3.4 Two-disk merger models…”

“…Examples of models with non-trivial Hermitian function G SS (T, T ) include warped Calabi-Yau throats [18][19][20][21][22][23], in which the Kähler potential takes the form…”

“…Its worldvolume theory includes a Volkov-Akulov fermion goldstino [3,4], which can be equivalently described in terms of a nilpotent scalar superfield S with S 2 (x, θ) = 0 [5][6][7][8][9][10][11][12][13][14][15]. This nilpotent superfield allows for a manifestly supersymmetric description of the uplift to a de Sitter minimum [16][17][18][19][20][21][22][23]. In a parallel development, it has been realized that nilpotent superfields have great potential as a model building tool in effective supergravity theories of inflation [24][25][26][27][28].…”

From linear to non-linear SUSY and back again

“…In this spirit, constrained superfields have been used for the effective description of inflationary models that are embedded in supergravity [15][16][17][18][19][20][21][22][23][24][25][26], but also to study more general brane supersymmetry breaking scenarios in string theory reductions to four dimensions. While explicit string constructions based on tachyon-free non-BPS systems are known since some time [27][28][29] and their non-linear supersymmetry has been studied in detail [30,31], their connection with the constrained superfields are still not fully understood [32][33][34][35][36][37][38]. This renewal of interest for non-linear realizations also led to various developments on the properties of the supersymmetry breaking sector in local supersymmetry [39][40][41][42][43][44][45][46][47].…”

“…Finally, if supersymmetry is never restored within a field theory, then it is not clear how generic the description in terms of constrained superfields can be. Work in this direction can be already found in [32][33][34][35][36][37][38].…”