RGEs
Calculating the RGEs with SARAH
SARAH calculates the renormalization group equations (RGEs) for the parameters of the (super)potential, the soft-breaking terms and the gauge couplings at one and two loop level. This is done by using the generic formulas of supersymmetry or a general quantum field theory . These expressions were extended by the results for several Abelian gauge groups and Dirac mass terms for gauginos . In addition, the gauge dependence in the running of the VEVs is included . Read also see the detials about the calculation.
SARAH writes the analytical expressions for all RGEs in separated files, and provides in addition a file to run the RGEs numerical with Mathematica, see RGE Running with Mathematica.
The calculation is started via
CalcRGEs[Options]
Options
The different options are
-
TwoLoop
, Value:True
orFalse
, Default:True
If also the two loop RGEs should be calculated. -
ReadLists
, Value:True
orFalse
, Default:False
If the RGEs have already be calculated, the results are saved in the output directory. The RGEs can be read from these files instead of doing the complete calculation again. -
VariableGenerations
, Value: List of particles, Default:{}
Some theories contain heavy superfields which should be integrated out above the SUSY scale. Therefore, it is possible to calculate the RGEs assuming the number of generations of specific superfields as free variable to make the dependence on these fields obvious. The new variable is namedNumberGenertions[X]
, whereX
is the name of the superfield. -
NoMatrixMultiplication
, Values:True
orFalse
, Default:False
Normally, the β-functions are simplified by writing the sums over generation indices as matrix multiplication. This can be switched off using this option. -
IgnoreAt2Loop
, Values: a list of parameters, Default:{}
The calculation of 2-loop RGEs for models with many new interactions can be very time-consuming. However, often one is only interested in the dominant effects of the new contributions at the 1-loop level. Therefore, IgnoreAt2Loop -> $LIST can be used to neglect parameters at the two-loop level The entries of $LIST can be superpotential or soft SUSY-breaking parameters as well as gauge couplings. -
WriteFunctionsToRun
,True
orFalse
, Default:True
Defines, if a file should be written to evaluate the RGEs numerically in Mathematica
Furthermore, the function PrepareRGEs
is used to prepare the RGEs for the RGE Running with Mathematica. To read or change its options run e.g. Options[PrepareRGEs]
or SetOptions[PrepareRGEs,OnlyDiagonal->False]
.
Output arrays
The β-functions for SUSY will be stored in the following arrays:
-
Gij
: Anomalous dimensions of all chiral superfields -
BetaWijkl
: Quartic superpotential parameters -
BetaYijk
: Trilinear superpotential parameters -
BetaMuij
: Bilinear superpotential parameters -
BetaLi
: Linear superpotential parameters -
BetaQijkl
: Quartic soft-breaking parameters -
BetaTijk
: Trilinear soft-breaking parameters -
BetaBij
: Bilinear soft-breaking parameters -
BetaSLi
: Linear soft-breaking parameters -
Betam2ij
: Scalar squared masses -
BetaMi
: Majorana Gaugino masses -
BetaGauge
: Gauge couplings -
BetaVEVs
: VEVs -
BetaDGi
: Dirac gaugino mass terms
and for non-SUSY models in
-
Gammaij
orGijS
: Anomalous dimensions of scalars -
GijF
: Anomalous dimensions of fermions -
GammaijHat
: gauge dependent part of running VEVs -
BetaGauge
: Gauge couplings -
BetaLijkl
: Quartic scalar couplings -
BetaYijk
: Interactions between two fermions and one scalar -
BetaTijk
: Cubic scalar interactions -
BetaMuij
: Bilinear fermion term -
BetaBij
: Bilinear scalar term -
BetaVEVs
: Vacuum expectation values
These arrays are also saved in the directory
../\SARAH/Output/"ModelName"/RGE
Conventions for the output
All RGEs are saved in three-dimension arrays with the following conventions:
{Parameter,1-Loop,2-Loop}
- The first entry contains the name of the parameter
- The second entry contains the one-loop β-function up to a factor 1/(16π2)
- The third entry contains the two loop β-function up to a factor (1/(16π2))2
For anomalous dimension the first entry is a bit different and the output reads
{{Field1,Field2},1-Loop,2-Loop}
Thus, the names of the two external fields are given which must not be identical in the presence of off-diagonal, anomalous dimensions.
Remarks
GUT normalization
The gauge couplings of U(1) gauge groups are often normalized at the GUT scale with respect to a specific GUT group. Therefore, it is possible to define for each gauge coupling the GUT-normalization by the corresponding entry in the parameters file. See parameters.m for more information.
Index contraction
Generally, the results contain sums over the generation indices of the particles in the loop. SARAH always tries to write them as matrix multiplications, in order to shorten the expressions. Therefore, new symbols are introduced:
-
MatMul[A,B,C,...][i,j]
: (ABC…)i, j. Matrix multiplication, also used for vector-matrix and vector-vector multiplication. -
trace[A,B,C,...]
: Tr(ABC…). Trace of a matrix or of a product of matrices. -
Adj[M]
: M†. Adjoint of a matrix -
Tp[M]
: MT. Transposed of a matrix
Some remarks about the output:
- To differ between generation and other indices during the calculation,
Kronecker[i,j]
is used for generation indices instead ofDelta[i,j]
. - The results for the scalar masses are simplified by using abbreviations for often appearing traces, see also Ref. . The definition of the traces are saved in the array
TraceAbbr
. - If the model contains parameters with three indices, matrix multiplication is automatically switched off and the results are given as sum over the involved indices. In addition, these expressions are simplified by replacing a parameter with three indices by a sum of parameters with two indices. The β function in this form a saved in NAME <> 3I with NAME stands for the standard array containing the RGEs.
Examples
-
β-function of Yukawa coupling The Yukawa couplings of the MSSM are saved in
BetaYijk
. The first entry consists of BetaYijk[ [1,1]]: Ye[i1,i2] ,i.e. this entry contains the β-functions for the electron Yukawa coupling. The corresponding one-loop β-function is
BetaYijk[ [1,2]]: (-9*g1^2*Ye[i1,i2])/5-3*g2^2*Ye[i1,i2]+3*trace[Yd,Adj[Yd]]*Ye[i1,i2]+ trace[Ye,Adj[Ye]]*Ye[i1, i2]+3*MatMul[Ye,Adj[Ye],Ye][i1, i2]
The two-loop β-function is saved in
BetaYijk[ [1,3]]
but we skip it here because of its length. -
Anomalous dimensions:
-
the anomalous dimensions for leptons in the SM is saved in
GijF
read {{e[{i1}], e[{i2}]}, (3g1^2XiKronecker[i1, i2])/5 + MatMul[Ye, Adj[Ye]][i1, i2], (-846g1^4Kronecker[i1, i2] - 5(3*(11g1^2 - 85g2^2 + 60trace[Yd, Adj[Yd]] + 20trace[Ye, Adj[Ye]])* MatMul[Ye, Adj[Ye]][i1, i2] + 10*MatMul[Ye, Adj[Ye], Ye, Adj[Ye]][i1, i2]))/200} -
In models with Vector-like states usually anomalous dimensions show up which mix fields. For instance {{SuR[{gen1, col1}], St1[{col2}]}, 2MatMul[conj[Yu], Yt][i1], ((-2g1^2)/5 + 6g2^2 - 8ScalarProd[Yt, conj[Yt]] - 6trace[Yu, Adj[Yu]]) MatMul[conj[Yu], Yt][i1] - 2*(MatMul[conj[Yu], Tp[Yd], conj[Yd], Yt][i1] + MatMul[conj[Yu], Tp[Yu], conj[Yu], Yt][i1])}
Here,
SuR
are the up-squarks from the MSSM andSt1
are new superfields. Note, even if the names for scalars are shown by conventions, the anomalous dimension apply for the superfields!
-
-
β-function of soft-breaking masses and abbreviations for traces The soft-breaking mass of the selectron is the first entry of
Betam2ij
Betam2ij[ [1,1]]: me2[i1,i2]and the one-loop β-function is saved in
Betam2ij[ [1,2]]
:(-24*g1^2*MassB*conj[MassB]+10*g1^2*Tr1[1])*Kronecker[i1,i2]/5 + 4*mHd2*MatMul[Ye,Adj[Ye]][i1,i2]+4*MatMul[T[Ye],Adj[T[Ye]]][i1,i2] + 2*MatMul[me2,Ye,Adj[Ye]][i1,i2]+4*MatMul[Ye, ml2, Adj[Ye]][i1,i2] + 2*MatMul[Ye,Adj[Ye],me2][i1,i2]
The definition of the element
Tr1[1]
is saved inTraceAbbr[ [1,1]]
:{Tr1[1], -mHd2 + mHu2 + trace[md2] + trace[me2] - trace[ml2] + trace[mq2] - 2*trace[mu2]}
-
Number of generations as variable: With CalcRGEs[VariableGenerations -> {q}]
the number of generations of the left-quark superfield is handled as variable. Therefore, the one-loop β-function of the hypercharge couplings reads
(63*g1^3)/10 + (g1^3*NumberGenerations[q])/10
-
No matrix multiplication Using matrix multiplication can be switched off by CalcRGEs[NoMatrixMultiplication -> True]
The one-loop β-function for the electron Yukawa coupling is now written as
sum[j2,1,3,sum[j1,1,3,conj[Yd[j2,j1]]*Yu[i1,j1]]*Yd[j2,i2]] + 2*sum[j2,1,3,sum[j1,1,3,conj[Yu[j1,j2]]*Yu[j1,i2]]*Yu[i1,j2]] + sum[j2,1,3,sum[j1,1,3,conj[Yu[j2,j1]]*Yu[i1,j1]]*Yu[j2,i2]] + (3*sum[j2,1,3,sum[j1,1,3,conj[Yu[j1,j2]]*Yu[j1,j2]]]*Yu[i1,i2])/2 + (3*sum[j2,1,3,sum[j1,1,3,conj[Yu[j2,j1]]*Yu[j2,j1]]]*Yu[i1,i2])/2 - (13*g1^2*Yu[i1,i2])/15-3*g2^2*Yu[i1,i2]-(16*g3^2*Yu[i1,i2])/3
-
Ignoring parameters at two-loop Using CalcRGEs[IgnoreAt2Loop -> {T[L1],T[L2],L1,L2}]
in the MSSM with trilinear RpV would ignore the λ and λ′ coupling as well as their soft-breaking equivalents in the calculation of the 2-loop RGEs.
Output
The RGEs calculated by SARAH are outputted in different formats:
- they are written in the internal SARAH format in the output directory
- they are included in the LaTeX output in a much more readable format
- they are exported into ,a format which can be used together with
NDSolve
of Mathematica to solve the RGEs numerically within Mathematica - they are exported into
Fortran
code which is used by SPheno