Selected Examples¶
Standard Model with internal polarization selection¶
Recola 1.5.0+ supports the selection of internal polarizations which is based on [BMP18], [BMP19] and has been used with Recola in [DP20], [DP21b] and [DP21a]. Examples of how to use this feature are given below:
program internal_projection
use recola
implicit none
integer, parameter :: dp = 8
real (kind=dp) :: p_full (0:3,1:6),p_full_prod(0:3,1:4), p_full_dec1(0:3,1:3), p_full_dec2(0:3,1:3)
real (kind=dp) :: A2(0:1), B2(0:1), C2(0:1), D2(0:1), E2(0:1)
real (kind=dp) :: M2prod, M2dec1, M2dec2, M2full
real (kind=dp) ::alphas, MW, MZ, wwidth, alpha
p_full(:,1)=[5000.0000000000000d0, 0.0000000000000000d0, 0.0000000000000000d0, 5000.0000000000000d0]
p_full(:,2)=[5000.0000000000000d0, 0.0000000000000000d0, 0.0000000000000000d0,-5000.0000000000000d0]
p_full(:,3)=[3243.8985189361665d0, 695.23069130847887d0,-3166.9342850974826d0,-100.29516884221320d0]
p_full(:,4)=[1756.1014810638335d0, 433.87511031166298d0,-1700.8566566424388d0,-52.263122770570874d0]
p_full(:,5)=[2249.2998992648813d0,-494.85571955991441d0, 2193.9693904301166d0, 31.083235152524409d0]
p_full(:,6)=[2750.7001007351187d0,-634.25008206022721d0, 2673.8215513098039d0, 121.47505646025964d0]
p_full_prod(:,1) = p_full(:,1)
p_full_prod(:,2) = p_full(:,2)
p_full_prod(:,3) = p_full(:,3) +p_full(:,4)
p_full_prod(:,4) = p_full(:,5) +p_full(:,6)
p_full_dec1(:,1) = p_full_prod(:,3)
p_full_dec1(:,2) = p_full(:,3)
p_full_dec1(:,3) = p_full(:,4)
p_full_dec2(:,1) = p_full_prod(:,4)
p_full_dec2(:,2) = p_full(:,5)
p_full_dec2(:,3) = p_full(:,6)
! input parameter
alphas = 0.117d0
MW = 80.3579736098775d0
MZ = 91.1534806191828d0
wwidth = 2.08429899827822d0
alpha = 7.555310522369d-3
! compute the full M^2
call use_gfermi_scheme_rcl(a=alpha)
call set_pole_mass_W_rcl(MW,wwidth)
call set_pole_mass_Z_rcl(MZ,0d0)
call set_complex_mass_scheme_rcl()
call set_print_level_squared_amplitude_rcl(3)
call set_resonant_particle_rcl("W-")
call define_process_rcl(1,"A A -> W-[-](nu_e~ e-) W+[-](mu+ nu_mu)","NLO")
call generate_processes_rcl
call compute_process_rcl(1, p_full, "NLO", A2)
call get_squared_amplitude_rcl(1,0,"LO",M2full)
write(*,*) "ME2 = ", M2full
call reset_recola_rcl()
call use_gfermi_scheme_rcl(a=alpha)
call set_pole_mass_W_rcl(MW,0d0)
call set_pole_mass_Z_rcl(MZ,0d0)
call set_on_shell_scheme_rcl()
! compute the production/decay M^2
call define_process_rcl(1,"A A -> W-[-] W+[-]","NLO")
call define_process_rcl(2," W-[-] -> nu_e~ e-","NLO")
call define_process_rcl(3," W+[-] -> mu+ nu_mu","NLO")
call generate_processes_rcl()
call compute_process_rcl(1, p_full_prod, "NLO", B2)
call compute_process_rcl(2, p_full_dec1, "NLO", C2)
call compute_process_rcl(3, p_full_dec2, "NLO", D2)
call get_squared_amplitude_rcl(1,0,"LO",M2prod)
call get_squared_amplitude_rcl(2,0,"LO",M2dec1)
call get_squared_amplitude_rcl(3,0,"LO",M2dec2)
write(*,*) "ME2 = ", M2prod*M2dec1*M2dec2/(MW*wwidth)**4
call reset_recola_rcl
end program internal_projection
- BMP18
Alessandro Ballestrero, Ezio Maina, and Giovanni Pelliccioli. $W$ boson polarization in vector boson scattering at the LHC. JHEP, 03:170, 2018. arXiv:1710.09339, doi:10.1007/JHEP03(2018)170.
- BMP19
Alessandro Ballestrero, Ezio Maina, and Giovanni Pelliccioli. Polarized vector boson scattering in the fully leptonic WZ and ZZ channels at the LHC. JHEP, 09:087, 2019. arXiv:1907.04722, doi:10.1007/JHEP09(2019)087.
- DP20
Ansgar Denner and Giovanni Pelliccioli. Polarized electroweak bosons in $\bf \text W^+\text W^-$ production at the LHC including NLO QCD effects. JHEP, 09:164, 2020. arXiv:2006.14867, doi:10.1007/JHEP09(2020)164.
- DP21a
Ansgar Denner and Giovanni Pelliccioli. NLO EW and QCD corrections to polarized ZZ production in the four-charged-lepton channel at the LHC. JHEP, 10:097, 2021. arXiv:2107.06579, doi:10.1007/JHEP10(2021)097.
- DP21b
Ansgar Denner and Giovanni Pelliccioli. NLO QCD predictions for doubly-polarized WZ production at the LHC. Phys. Lett. B, 814:136107, 2021. arXiv:2010.07149, doi:10.1016/j.physletb.2021.136107.
