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().