⚠️ Discalimer: The contents of this repository are outdated and no longer maintained. While they may provide a useful starting point, the files here should not be used in production as is. See notes below for known issues. This fork may contain more up-to-date files and instructions for event generation.
This repository contains model files necessary for generation of semi-visible jet Monte Carlo signal events in MadGraph.
Please see 1707.05326 and 1503.00009 for
for further details. Please note that a recent version of PYTHIA (> 8.226) including the Hidden Valley module
and running of the dark coupling is required when implementing the subsequent dark hadronization.
UFO files associated with two UV completions are provided:
An s-channel production (DMsimp_s_spin1) mediated through a new heavy Z'. The model provided is a modified version of the spin-1 DMsimp model (http://feynrules.irmp.ucl.ac.be/wiki/DMsimp)
implemented through FeynRules.
A t-channel production (DMsimp_tchannel) where the dark and visible sectors interact through a new scalar bi-fundamental.
The bi-fundamentals are denoted with su11, su12, su21, su22..., where u etc explicitly specifies the QCD flavour index
and the numbers are the explicit dark non-Abelian group indices. Similarly, the dark quarks are labeled as qv11, qv12, qv21, qv22.
A FeynRules model file (DMsimp_tchannel.fr) as well as the Mathematica notebook (DMsimp_tchannel.nb) used to generated the UFO output
are also provided.
Please note that a modified version of MadGraph using the patch included here
is required to ensure a stable cross section for event generation using this model.
Additionally, the param_card.dat generated while running t-channel production may assume a fixed width for the mediator, which may not be desired. In this case, the param_card.dat can be manually modified as follows to automatically compute the mediator width (see here for discussion):
DECAY 9000005 Auto
DECAY 9000006 Auto
...
DECAY 9000028 Auto
- Inclusive s-channel production:
import DMsimp_s_spin1
define j = g u c t d b s g u~ c~ t~ d~ b~ s~
generate p p > xd xd~
add process p p > xd xd~ j
add process p p > xd xd~ j j
output sig_schannel
- Inclusive t-channel production:
import DMsimp_tchannel
define gv = gv11 gv12 gv21 gv22
define gv~ = gv11~ gv12~ gv21~ gv22~
define j = g u c t d b s g u~ c~ t~ d~ b~ s~
generate p p > gv gv~
add process p p > gv gv~ j
add process p p > gv gv~ j j
output sig_tchannel
As noted above, a recent version of PYTHIA (>~ 8.226) including the Hidden Valley (HV) module
and running of the dark coupling is required when implementing the subsequent dark hadronization.
In order to be able to use the HV module, the PDG IDs of the dark particles must be changed in the LHE files
for PYTHIA to be
able to recognize and shower these properly. This can be done as follows:
- For the s-channel model
sed -i 's/5000521/4900101/g' <LHE filename>
- For the t-channel model
sed -i 's/49001010/4900101/g' <LHE filename>
sed -i 's/49001011/4900101/g' <LHE filename>
sed -i 's/49001012/4900101/g' <LHE filename>
sed -i 's/49001013/4900101/g' <LHE filename>
sed -i 's/49001014/4900101/g' <LHE filename>
For questions or issues please contact:
- Tim Lou; hlou at berkeley dot edu
- Siddharth Mishra-Sharma; smsharma at princeton dot edu