33 f(-p₁) + f(-p₂) → Z(→ b(p₃) + b(p₄))

33.1 Z-boson production, processes 31–33

These processes represent the production of a Z boson which subsequently decays either into electrons (nproc=31), neutrinos (nproc=32) or bottom quarks (nproc=33). Where appropriate, the effect of a virtual photon is also included. As noted above, for nproc=31 and nproc=33 the constraint m34min > 0 is obligatory. The calculation may be performed at LO, NLO and NNLO [1, 2] although the NLO and NNLO calculation of process 33 does not include radiation from the bottom quarks (i.e. radiation occurs in the initial state only).

This process can be calculated at LO, NLO, and NNLO. NLO calculations can be performed by subtraction, zero-jettiness slicing and q_T-slicing. NNLO calculations can be performed by zero-jettiness slicing and q_T-slicing.

To calculate the total cross section to on-shell Z bosons, we take process (nproc=32), (no γ^* contribution) and set (zerowidth=.true.) and (removebr =.true.). When removebr is true in process 31, the Z boson does not decay.

33.2 Plotter

nplotter_Z_only.f is the default plotting routine.

33.3 Example input and output file(s)

input33.ini process33.out

References