Superspace evaluation of the two-loop effective potential for the O'Raifeartaigh model

All-order spurion-corrected superpropagators and superfield Feynman rules are employed to systematically compute a two-loop corrected effective potential for the O'Raifeartaigh model, that realizes spontaneous supersymmetry breaking. Though the shifted superpropagators are rather nontrivial, superspace techniques may be suitably extended and confirm their efficacy in computing radiative corrections even when supersymmetry breakdown occurs.Comment: 24 pages, 2 figures, revtex4, 2 pages added, new appendix adde

Supergraph Approach in a Higher-order LDE Calculation of the Effective Potential for F-type Broken SUSY

In this work, we adopt the simplest model that spontaneously breaks supersymmetry, namely, the minimal O'Raifeartaigh model. The effective potential is computed in the framework of the linear delta expansion (LDE) approach up to the order $\delta^2$, conjugated with superspace and supergraph techniques. The latter can be duly mastered even if supersymmetry is no longer exact and the efficacy of the superfield approach in connection with the LDE procedure is confirmed according to our investigation. That opens up a way for a semi-nonperturbative superspace computation which allows us to deal with spontaneously broken supersymmetric models and encourages us to go further and apply this treatment to the Minimal Supersymmetric Standard Model (MSSM) precision tests.Comment: 42 pages, 22 figures, text modified, new paragraph added in the conclusions, revtex

Superspace approach to the renormalization of the O'Raifeartaigh model up to the second order in the LDE parameter

We adopt a superspace/supergraph formalism to pursue the investigation of the structure of one- and two-loop divergences in the frame of the minimal O'Raifeartaigh model that realizes the F-term spontaneous supersymmetry breaking. The linear delta expansion(LDE) procedure is introduced and renormalization is carried out up to the second order in the LDE expansion parameter. In agreement with the nonrenormalization theorem for the (chiral/antichiral) matter potential of ${\mathcal N}=1, \ D=4$ supersymmetry, our explicit supergraph calculations confirm that only the K\"{a}hler potential is actually renomalized.Comment: 23 pages, 4 figures, revtex4. arXiv admin note: text overlap with arXiv:0904.467

Linear delta expansion applied to the O'Raifeartaigh model

We reassess the method of the linear delta expansion for the calculation of effective potentials in superspace, by adopting the improved version of the super-Feynman rules in the framework of the O'Raifeartaigh model for spontaneous supersymmetry breaking. The effective potential is calculated using both the fastest apparent convergence and the principle of minimal sensitivity criteria and the consistency and efficacy of the method are checked in deriving the Coleman-Weinberg potential.Comment: 20 pages, 2 figures, revtex4, revised and extended, published versio

Mass dimension one fermions and their gravitational interaction

We investigate in detail the interaction between the spin-${1/2}$ fields endowed with mass dimension one and the graviton. We obtain an interaction vertex that combines the characteristics of scalar-graviton and Dirac's fermion-graviton vertices, due to the scalar-dynamic attribute and the fermionic structure of this field. It is shown that the vertex obtained obeys the Ward-Takahashi identity, ensuring the gauge invariance for this interaction. In the contribution of the mass dimension one fermion to the graviton propagator at one-loop, we found the conditions for the cancellation of the tadpole term by a cosmological counter-term. We calculate the scattering process for arbitrary momentum. For low energies, the result reveals that only the scalar sector present in the vertex contributes to the gravitational potential. Finally, we evaluate the non relativistic limit of the gravitational interaction and obtain an attractive Newtonian potential, as required for a dark matter candidate.Comment: 8 pages, 3 figure