Skip to content

GitLab

Last edited by Martin Gabelmann
Page history

Models_with_another_gauge_group_at_the_SUSY_scale

Models with another gauge group at the SUSY scale

Important Note

This functionality was replaced in SARAH 4.9.0 by the new option

DEFINITION[MatchingConditions]

see Matching to the SM in SPheno.

General

Some SUSY models have the distinct feature that they gauge group at the SUSY scale doesn’t consist of S**U(3)C × S**U(2)L × U(1)Y. This is for instance the case in left-right models in which U(1)R × U(1)B − L is just broken around the SUSY scale (see e.g. Ref.  and references therein). This special feature has to be taken into account in some calculations. For instance, the calculation of the running couplings at the EW scale assumes that the hypercharge is present. Therefore, SARAH has to create in this kind of models an auxiliary variable for the hypercharge coupling called gYaux. This is done by adding

AuxiliaryHyperchargeCoupling = True;

in SPheno.m. In addition, the user has to define a relation between the existing gauge couplings and the hypercharge coupling. For instance, in the model mentioned above, this relation reads

ExpressionAuxHypercharge =Sqrt[(gBL*gR - gBLgR*gRgBL)^2/((gBLgR - gR)^2 + (gBL - gRgBL)^2)];

Note, if kinetic mixing is neglected, this reduces to the more familiar form of \sqrt{g^2_{BL} g_R/(g_R^2 + g_{BL}^2)}. When setting the boundary conditions to relate the gauge couplings, one has to make sure that always the relations for the not GUT-normalized values are used. For instance,

BoundaryEWSBScale = {
  {gYauxt, Sqrt[5/3]*gYaux},
  {gR, g1RBLFactor*gYauxt},
  {gRgBLt, 1*gRgBL},
  {gBLgRt, Sqrt[2/3]*gBLgR},
  {gBLt, (5 gBLgRt gR gRgBLt - Sqrt[6] gRgBLt gYauxt^2
      + Sqrt[(3 gBLgRt^2 - 2 Sqrt[6] gBLgRt gR + 2 gR^2) *
        (5 (gR^2 + gRgBLt^2) - 3 gYauxt^2) gYauxt^2])/(5 gR^2 - 3 gYauxt^2)},
  {gBL, Sqrt[3/2]*gBLt},
  {TanBetaR, TanBetaRinput},
  {vChiR, vR*TanBetaR/Sqrt[1 + TanBetaR^2]},
  {vChiRb, vR*1/Sqrt[1 + TanBetaR^2]}};

Here, g1RBLFactor is the ratio of gR/gYaux which has been calculated in the iteration before

BoundaryEWSBScaleRunningDown = {
  {gBLt, gBL*Sqrt[2/3]},
  {gRgBLt, 1*gRgBL},
  {gBLgRt, Sqrt[2/3]*gBLgR},
  {gYaux, Sqrt[5*(gBLt*gR - gBLgRt*gRgBLt)^2/(3*(gBLt^2 + gBLgRt^2)
     + 2*(gR^2 + gRgBLt^2) - 2*Sqrt[6]*(gR*gBLgRt + gBLt*gRgBLt))]},
  {g1RBLFactor, gR/gYaux},
  {gYaux, Sqrt[3/5]*gYaux}
 };

See also