## Dark Matter Processes

This page contains the production of Dirac fermion Dark Matter via new s-channel mediators. An example how these processes can be run is found in `main75.cc`.

### Scalar Mediator

`flag` DM:gg2S2XX (`default = off`)
Scattering g g → S → X Xbar. Code 6001. S is assumed to be on-shell.

`flag` DM:gg2S2XXj (`default = off`)
Scattering g g →S → X Xbar j. Code 6002. S is assumed to be on-shell. (Not validated)

Fermion couplings to scalar S are assumed to be proportional to mass of the fermion and couplings are the factor multiplying SM Higgs coupling (i.e. sin(mixing) in case of portal models).

`parm` Sdm:vf (`default = 0.1`)
Scalar coupling of SM fermions.

`parm` Sdm:af (`default = 0`)
Pseudo-scalar coupling of SM fermions.

`parm` Sdm:vX (`default = 1.0`)
Scalar coupling of DM fermion.

`parm` Sdm:aX (`default = 0`)
Pseudo-scalar coupling of DM fermion.

### Vector Mediator Z'

The Vector mediator model assumes a simplified U(1) model with couplings to fermionic Dark Matter. Both vector and axial couplings are possible.

`flag` DM:ffbar2Zp2XX (`default = off`)
Scattering f fbar →Z'^0 → X Xbar. Code 6001. Z' is assumed to be on-shell.

`flag` DM:ffbar2ZpH (`default = off`)
Scattering f fbar →Z'^0 H . Code 6004. Z' is assumed to be on-shell. The coupling of the Z' to the SM Higgs is given by the parameter `Zp:coupH`. Interference with gamma/Z currently not implemented, therefore this is only suitable when Z' → X Xbar. This can be ensured using
55:onMode = off
55:onIfAny = 52

`flag` DM:ffbar2Zp2XXj (`default = off`)
Scattering f fbar →Z'^0 → X Xbar. Code 6002. Z' is assumed to be on-shell. (Not validated)

`flag` DM:qg2Zp2XXj (`default = off`)
Scattering f fbar →Z'^0 → X Xbar. Code 6003. Z' is assumed to be on-shell. (Not validated)

The couplings of the Z'^0 to quarks and leptons are be assumed universal, i.e. generation-independent. The choice of fixed axial and vector couplings implies a resonance width that increases linearly with the Z' mass.

Here are the couplings:

`parm` Zp:gZp (`default = 0.1`)
Gauge coupling of new U(1).

`parm` Zp:coupH (`default = 0.1`)
Coupling to SM higgs.

`parm` Zp:vu (`default = 1`)
Vector coupling of up-type quarks.

`parm` Zp:au (`default = 0`)
Axial coupling of up-type quarks.

`parm` Zp:vd (`default = 1`)
Vector coupling of down-type quarks.

`parm` Zp:ad (`default = 0`)
Axial coupling of down-type quarks.

`parm` Zp:vl (`default = 1`)
Vector coupling of charged leptons.

`parm` Zp:al (`default = 0`)
Axial coupling of charged leptons.

`parm` Zp:vv (`default = 1`)
Vector coupling of neutrinos.

`parm` Zp:av (`default = 0`)
Axial coupling of neutrinos.

`parm` Zp:vX (`default = 1`)
Vector coupling of DM fermion.

`parm` Zp:aX (`default = 0`)
Axial coupling of DM fermion.