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NMSSM

In the Next-to-Minimal Supersymmetric Standard Model (NMSSM), three new particles appear: a new CP-even Higgs boson $\H ^0_3$ (code 45), a new CP-odd Higgs boson $\mathrm{A}^0_2$ (code 46), and an additional neutralino $\chi_5^0$ (code 1000045), where the particle codes are the ones tentatively adopted by the SUSY Les Houches Accord (SLHA) community [All06].

PYTHIA does not contain any internal machinery for doing calculations in the NMSSM. Thus, the basic scattering processes should be generated by an external program (e.g. COMPHEP/CALCHEP [Puk99]) and handed to PYTHIA via the Les Houches Accord interface for parton-level events (LHA). This should then be combined with either setting the NMSSM resonance decays by hand, or by reading in an SLHA decay table prepared by an external decay package (e.g. NMHDECAY [Ell05]). One possible chain of steps for generating fully simulated events for the NMSSM, starting from a high-scale model definition, would thus be (see e.g. [Puk05]):

82.
Obtain the EW scale masses and couplings for the model (e.g. by running NMHDECAY), and store the results as a SLHA spectrum file.
83.
Compute decay widths and branching ratios for all relevant particles (by hand or using some code), and store the resulting numbers in the SLHA decay table format.
84.
Pass the spectrum to an NMSSM Matrix Element level generator (e.g. COMPHEP/CALCHEP), and obtain a set of elementary $2 \to 2$ (or $2 \to$ `a few') scatterings.
85.
Read in the SLHA spectrum and decay table into PYTHIA using IMSS(1) = 11 and IMSS(13) = 1 (you need to set IMSS(21) and possibly IMSS(22) as well).
86.
Read in the ME level events into PYTHIA using the LHA interface routines UPINIT and UPEVNT.


next up previous contents
Next: Long-lived coloured sparticles Up: Supersymmetry Previous: -Parity Violation   Contents
Stephen Mrenna 2007-10-30