Support of Dirac Gauginos

Another feature which became popular in the last years are models with Dirac gauginos. In these models mass termsm_D^ϕ̂_iAλ_Aψ_i between gauginosλ_A and a fermionic componentψ_i of the chiral superfieldϕ̂_i in the adjoint representation of the gauge groupA are present. In addition, also newD-terms are introduced in these models . Thus, the new terms in the Lagrangian are

\mathfrak{L}_{DG} = - m^{\hat \phi_i A}_D \lambda^a_A \psi_i + \sqrt{2} m^{\hat \phi_i A}_D \phi_i D_A

D_A is the auxiliary component of the vector superfield of the groupA. To allow for Dirac mass terms, these models come always with an extended matter sector: to generate Dirac mass terms for all MSSM gauginos at least one singlet, one triplet underS**U(2) and one octet underS**U(3) must be added. Furthermore, models with Dirac gauginos generate also new structures in the RGEs . All of this is fully supported in SARAH. If Dirac masses for gauginos are explicitly turned on in SARAH, it will check for all allowed combinations of vector and chiral superfields which can generate Dirac masses and which are consistent with all symmetries. For instance, in models with several gauge singlets, the bino might even get several Dirac mass terms.

Superpotential, soft-terms and non-canonical interactions

The matter interactions in SUSY models are usually fixed by the superpotential and the soft-SUSY breaking terms. SARAH fully supports all renormalizable terms in the superpotential

W = c_LL_iϕ̂_i + c_MM^i**jϕ̂_iϕ̂_j + c_TY^ijkϕ̂_iϕ̂_jϕ̂_k

and generates the corresponding soft-breaking terms

L_S**B, W = c_Lt_iϕ_i + c_MB^i**jϕ_iϕ_j + c_TT^ijkϕ_iϕ_jϕ_k + h.c.

c_L,c_M,c_T are real coefficients. All parameters are treated by default in the most general way by taking them as complex tensors of appropriate order and dimension. If identical fields are involved in the same coupling, SARAH derives also the symmetry properties for the parameter. As discussed below, SARAH can also handle to some extent non-renormalizable terms with four superfields in the superpotential

W_N**R = c_WW^ijk**lϕ̂_iϕ̂_jϕ̂_kϕ̂_l

From the superpotential, all theF-terms

|F|^2 = \sum_i \left|\frac{\partial \tilde{W}}{\partial \phi_i}\right|^2

and interactions of matter fermions

\mathfrak{L}_Y = - \frac{1}{2} \frac{\partial^2 \tilde{W}}{\partial \phi_i \partial \phi_j} \psi_i \psi_j + \mbox{h.c.} ,

are derived. HereW̃ is the superpotentialW with all superfieldsϕ̂_i replaced by their scalar componentϕ_i.ψ_i is the fermionic component of that superfield. Usually, theF- andD-terms and the soft-breaking terms for chiral and vector superfields fix the full scalar potential of the model. However, in some cases also non-canonical terms should be studied. These are for instance non-holomorphic soft-terms

𝔏_S**B, N**H = T̃^ijkϕ_iϕ_jϕ_k^*

Those can be added as well and they are taken into account in the calculation of the vertices and masses and as consequence also in all loop calculations. However, they are not included in the calculation of the RGEs because of the lack of generic results in literature.

See also