# Process definition and generation¶

## Process definition¶

 define_process_rcl(npr,process,order) Defines a process via the process string process at order order and assigns the process id npr to it.

## Coupling power selection¶

The orders associated to couplings for a given theory define a power-counting according to which amplitudes are ordered and computed. For theories with an SM-like gauge group the electric charge $$e$$ and the strong coupling constant $$g_\mathrm{s}$$ are identified as fundamental couplings. They define the fundamental order and the derived order for other couplings and counterterm parameters:

 Coupling Order $$g_\mathrm{s}$$ $$\mathrm{QCD}^1$$ $$\alpha_\mathrm{s}$$ $$\mathrm{QCD}^2$$ $$e$$ $$\mathrm{QED}^1$$ $$\alpha$$ $$\mathrm{QED}^2$$ …

Processes can be defined requesting a particular order in fundamental couplings. For SM-like gauge group it is enough to select specific powers of $$g_\mathrm{s}$$ and the corresponding valid orders in $$e$$ are automaically selected. The selections are applied using one of the following functions:

 select_all_gs_powers_BornAmpl_rcl(npr) Selects all the contribution to the Born amplitude for the process with process number npr. unselect_all_gs_powers_BornAmpl_rcl(npr) Unselects all the contribution to the Born amplitude for the process with process number npr. select_gs_power_BornAmpl_rcl(npr,gspower) Selects the contribution to the Born amplitude with $$g_\mathrm{s}$$ power gspower for the process with process number npr. unselect_gs_power_BornAmpl_rcl(npr,gspower) Unselects the contribution to the Born amplitude with $$g_\mathrm{s}$$ power gspower for the process with process number npr. select_all_gs_powers_LoopAmpl_rcl(npr) Selects all the contribution to the Born amplitude for the process with process number npr. unselect_all_gs_powers_LoopAmpl_rcl(npr) Unselects all the contribution to the Born amplitude for the process with process number npr. select_gs_power_LoopAmpl_rcl(npr, gspower) Selects the contribution to the Loop amplitude with $$g_\mathrm{s}$$ power gspower for the process with process number npr. unselect_gs_power_LoopAmpl_rcl(npr,gspower) Unselects the contribution to the Loop amplitude with $$g_\mathrm{s}$$ power gspower for the process with process number npr.

For theories with more than two fundamental orders or in EFT the following functions should be used:

 select_power_BornAmpl_rcl(npr,cid,pow) Selects for the process with process number npr the contribution to the Born amplitude with power pow in the fundamental order cid. unselect_power_BornAmpl_rcl(npr,cid,pow) Selects the contributions to the Born amplitude with power power of the fundanmetal order cid for the process with identifier npr. select_all_powers_BornAmpl_rcl(npr) Selects all contributions to the Born amplitude with any power of orders. unselect_all_powers_BornAmpl_rcl(npr) Unselects all contributions to the Born amplitude with any power of orders. select_power_LoopAmpl_rcl(npr,cid,pow) Selects for the process with process number npr the contribution to the Loop amplitude with power power in the fundamental order cid. unselect_power_LoopAmpl_rcl() Selects all contributions to the Loop amplitude with any power of orders. select_all_powers_LoopAmpl_rcl(npr) Selects all contributions to the Loop amplitude with any power of orders. unselect_all_powers_LoopAmpl_rcl(npr) Unselects all contributions to the Loop amplitude with any power of orders.

### Resonance selection¶

 set_resonant_squared_momentum_rcl(npr,res,ps) Sets for the resonance with resonance number res for the process with process number npr the squared momentum of the denominator of the resonant propagator to ps. set_resonant_particle_rcl(pname) Tags the particle with name pname as resonant. switchon_resonant_selfenergies_rcl Sets the value of resSE to .true. switchoff_resonant_selfenergies_rcl Sets the value of resSE to .true.

### Quark-flow selection¶

 set_quarkline_rcl(npr,q1,q2) Enforces a quark-flow between two quarks q1 and q2.

## Process generation¶

 generate_processes_rcl() Generates processes which were defined using define_process_rcl(). process_exists_rcl(npr) Returns whether a process with id npr exists after generation generate_processes_rcl().