Higgs Processes
 
  - Standard-Model Higgs, basic processes
- Standard-Model Higgs, further processes
- Beyond-the-Standard-Model Higgs, introduction
- Beyond-the-Standard-Model Higgs, basic processes
- Beyond-the-Standard-Model Higgs, further processes
- Parameters for Beyond-the-Standard-Model Higgs production and decay
This page documents Higgs production within and beyond the Standard Model 
(SM and BSM for short). This includes several different processes and, 
for the BSM scenarios, a large set of parameters that would only be fixed 
within a more specific framework such as MSSM. Some choices can be made 
irrespective of the particular model:flag   Higgs:cubicWidth   
 (default = off)
The partial width of a Higgs particle to a pair of gauge bosons, 
W^+ W^- or Z^0 Z^0, depends cubically on the 
Higgs mass. When selecting the Higgs according to a Breit-Wigner, 
so that the actual mass mHat does not agree with the 
nominal m_Higgs one, an ambiguity arises which of the 
two to use [Sey95]. The default is to use a linear 
dependence on mHat, i.e. a width proportional to 
m_Higgs^2 * mHat, while on gives a 
mHat^3 dependence. This does not affect the widths to 
fermions, which only depend linearly on mHat. 
This flag is used both for SM and BSM Higgs bosons. 
   
 
flag   Higgs:runningLoopMass   
 (default = on)
The partial width of a Higgs particle to a pair of gluons or photons, 
or a gamma Z^0 pair, proceeds in part through quark loops, 
mainly b and t. There is some ambiguity what kind 
of masses to use. Default is running MSbar ones, but alternatively 
fixed pole masses are allowed (as was standard in PYTHIA 6), which 
typically gives a noticeably higher cross section for these channels. 
(For a decay to a pair of fermions, such as top, the running mass is 
used for couplings and the fixed one for phase space.) 
   
 
flag   Higgs:clipWings   
 (default = on)
The Breit-Wigner shape of a Higgs is nontrivial, owing to the rapid 
width variation with the mass of a Higgs. This implies that a Higgs 
of low nominal mass may still acquire a non-negligible high-end tail. 
The validity of the calculation may be questioned in these wings. 
With this option on, the Higgs:wingsFac value is used to 
cut away the wings. 
Warning: with this option on, the allowed mass range is 
shrunk, but never widened. This can lead to inconsistencies if a run 
consists of several subruns with different Higgs masses. The 
id:mMin and id:mMax values should therefore be 
reset (e.g. to the defaults 50. and 0.) when id:m0 is 
changed. 
   
 
parm   Higgs:wingsFac   
 (default = 50.; minimum = 0.)
With Higgs:clipWings on, all Higgs masses which deviate 
from the nominal one by more than Higgs:wingsFac 
times the nominal width are forbidden. This is achieved by setting 
the mMin and mMax values of the Higgs states 
at initialization. These changes never  allow a wider range than already 
set by the user, alternatively by the current default values, see 
warning above. 
   
 
 
One setting is specific to the Standard Model: 
 
flag   HiggsSM:NLOWidths   
 (default = on)
The partial width of the SM Higgs particle are multiplied by the 
respective factors needed to bring the LO widths encoded in PYTHIA 
to the NLO ones recommended by the LHCXSWG. The multiplicative 
factors have been derived for a 125 GeV Higgs, but should apply for a 
reasonable mass range around that value. 
   
 
 
Standard-Model Higgs, basic processes
 
 
This section provides the standard set of processes that can be 
run together to provide a reasonably complete overview of possible 
production channels for a single SM Higgs. 
The main parameter is the choice of Higgs mass, which can be set in the 
normal ParticleData database; thereafter the properties 
within the SM are essentially fixed. 
 
flag   HiggsSM:all   
 (default = off)
Common switch for the group of Higgs production within the Standard Model. 
   
 
flag   HiggsSM:ffbar2H   
 (default = off)
Scattering f fbar → H^0, where f sums over available 
flavours except top. Related to the mass-dependent Higgs point coupling 
to fermions, so at hadron colliders the bottom contribution will 
dominate. 
Code 901. 
   
 
flag   HiggsSM:gg2H   
 (default = off)
Scattering g g → H^0 via loop contributions primarily from 
top. 
Code 902. 
   
 
flag   HiggsSM:gmgm2H   
 (default = off)
Scattering gamma gamma → H^0 via loop contributions primarily 
from top and W. 
Code 903. 
   
 
flag   HiggsSM:ffbar2HZ   
 (default = off)
Scattering f fbar → H^0 Z^0 via s-channel Z^0 
exchange. 
Code 904. 
   
 
flag   HiggsSM:ffbar2HW   
 (default = off)
Scattering f fbar → H^0 W^+- via s-channel 
W^+- exchange. 
Code 905. 
   
 
flag   HiggsSM:ff2Hff(t:ZZ)   
 (default = off)
Scattering f f' → H^0 f f' via Z^0 Z^0 fusion. 
Code 906. 
   
 
flag   HiggsSM:ff2Hff(t:WW)   
 (default = off)
Scattering f_1 f_2 → H^0 f_3 f_4 via W^+ W^- fusion. 
Code 907. 
   
 
flag   HiggsSM:gg2Httbar   
 (default = off)
Scattering g g → H^0 t tbar via t tbar fusion 
(or, alternatively put, Higgs radiation off a top line). 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 908. 
   
 
flag   HiggsSM:qqbar2Httbar   
 (default = off)
Scattering q qbar → H^0 t tbar via t tbar fusion 
(or, alternatively put, Higgs radiation off a top line). 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 909. 
   
 
 
Standard-Model Higgs, further processes
 
 
A number of further production processes has been implemented, that 
are specializations of some of the above ones to the high-pT 
region. The sets therefore could not be used simultaneously 
without unphysical double-counting, as further explained below. 
They are not switched on by the HiggsSM:all flag, but 
have to be switched on for each separate process after due consideration. 
 
 
The first three processes in this section are related to the Higgs 
point coupling to fermions, and so primarily are of interest for 
b quarks. It is here useful to begin by reminding that 
a process like b bbar → H^0 implies that a b/bbar 
is taken from each incoming hadron, leaving behind its respective 
antiparticle. The initial-state showers will then add one 
g → b bbar branching on either side, so that effectively 
the process becomes g g → H0 b bbar. This would be the 
same basic process as the g g → H^0 t tbar one used for top. 
The difference is that (a) no PDF's are defined for top and 
(b) the shower approach would not be good enough to provide sensible 
kinematics for the H^0 t tbar subsystem. By contrast, owing 
to the b being much lighter than the Higgs, multiple 
gluon emissions must be resummed for b, as is done by PDF's 
and showers, in order to obtain a sensible description of the total 
production rate,  when the b quarks predominantly are produced 
at small pT values. 
 
flag   HiggsSM:qg2Hq   
 (default = off)
Scattering q g → H^0 q. This process gives first-order 
corrections to the f fbar → H^0 one above, and should only be 
used to study  the high-pT tail, while f fbar → H^0 
should be used for inclusive production. Only the dominant c 
and b contributions are included, and generated separately 
for technical reasons. Note that another first-order process would be 
q qbar → H^0 g, which is not explicitly implemented here, 
but is obtained from showering off the lowest-order process. It does not 
contain any b at large pT, however, so is less 
interesting for many applications. 
Code 911. 
   
 
flag   HiggsSM:gg2Hbbbar   
 (default = off)
Scattering g g → H^0 b bbar. This process is yet one order 
higher of the b bbar → H^0 and b g → H^0 b chain, 
where now two quarks should be required above some large pT 
threshold. 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 912. 
   
 
flag   HiggsSM:qqbar2Hbbbar   
 (default = off)
Scattering q qbar → H^0 b bbar via an s-channel 
gluon, so closely related to the previous one, but typically less 
important owing to the smaller rate of (anti)quarks relative to 
gluons. 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 913. 
   
 
 
The second set of processes are predominantly first-order corrections 
to the g g → H^0 process, again dominated by the top loop. 
We here only provide the kinematical expressions obtained in the 
limit that the top quark goes to infinity, but scaled to the 
finite-top-mass coupling in g g → H^0. (Complete loop 
expressions are available e.g. in PYTHIA 6.4 but are very lengthy.) 
This provides a reasonably accurate description for "intermediate" 
pT values, but fails when the pT scale approaches 
the top mass. 
 
flag   HiggsSM:gg2Hg(l:t)   
 (default = off)
Scattering g g → H^0 g via loop contributions primarily 
from top. 
Code 914. 
   
 
flag   HiggsSM:qg2Hq(l:t)   
 (default = off)
Scattering q g → H^0 q via loop contributions primarily 
from top. Not to be confused with the HiggsSM:qg2Hq 
process above, with its direct fermion-to-Higgs coupling. 
Code 915. 
   
 
flag   HiggsSM:qqbar2Hg(l:t)   
 (default = off)
Scattering q qbar → H^0 g via an s-channel gluon 
and loop contributions primarily from top. Is strictly speaking a 
"new" process, not directly derived from g g → H^0, and 
could therefore be included in the standard mix without double-counting, 
but is numerically negligible. 
Code 916. 
   
 
 
Beyond-the-Standard-Model Higgs, introduction
 
 
Further Higgs multiplets arise in a number of scenarios. We here 
concentrate on the MSSM scenario with two Higgs doublets, but with 
flexibility enough that also other two-Higgs-doublet scenarios could 
be represented by a suitable choice of parameters. Conventionally the 
Higgs states are labeled h^0, H^0, A^0 and H^+-. 
If the scalar and pseudocalar states mix the resulting states are 
labeled H_1^0, H_2^0, H_3^0. In process names and parameter 
explanations both notations will be used, but for settings labels 
we have adapted the shorthand hybrid notation H1 for 
h^0(H_1^0), H2 for H^0(H_2^0) and 
A3 for A^0(H_3^0). (Recall that the 
Settings database does not distinguish upper- and lowercase 
characters, so that the user has one thing less to worry about, but here 
it causes problems with h^0 vs. H^0.) We leave the issue 
of mass ordering between H^0 and A^0 open, and thereby 
also that of H_2^0 and H_3^0. 
 
flag   Higgs:useBSM   
 (default = off)
Master switch to initialize and use the two-Higgs-doublet states. 
If off, only the above SM Higgs processes can be used, with couplings 
as predicted in the SM. If on, only the below BSM Higgs processes can 
be used, with couplings that can be set freely, also found further down 
on this page. 
   
 
 
Beyond-the-Standard-Model Higgs, basic processes
 
 
This section provides the standard set of processes that can be 
run together to provide a reasonably complete overview of possible 
production channels for a single neutral Higgs state in a two-doublet 
scenarios such as MSSM. The list of processes for neutral states closely 
mimics the one found for the SM Higgs. Some of the processes 
vanish for a pure pseudoscalar A^0, but are kept for flexibility 
in cases of mixing with the scalar h^0 and H^0 states, 
or for use in the context of non-MSSM models. This should work well to 
represent e.g. that a small admixture of the "wrong" parity would allow 
a process such as q qbar → A^0 Z^0, which otherwise is 
forbidden. However, note that the loop integrals e.g. for 
g g → h^0/H^0/A^0 are hardcoded to be for scalars for the 
former two particles and for a pseudoscalar for the latter one, 
so absolute rates would not be correctly represented in the case of 
large scalar/pseudoscalar mixing. 
 
flag   HiggsBSM:all   
 (default = off)
Common switch for the group of Higgs production beyond the Standard Model, 
as listed below. 
   
 
1) h^0(H_1^0) processes
 
 
flag   HiggsBSM:allH1   
 (default = off)
Common switch for the group of h^0(H_1^0) production processes. 
   
 
flag   HiggsBSM:ffbar2H1   
 (default = off)
Scattering f fbar → h^0(H_1^0), where f sums over 
available flavours except top. 
Code 1001. 
   
 
flag   HiggsBSM:gg2H1   
 (default = off)
Scattering g g → h^0(H_1^0) via loop contributions primarily 
from top. 
Code 1002. 
   
 
flag   HiggsBSM:gmgm2H1   
 (default = off)
Scattering gamma gamma → h^0(H_1^0) via loop contributions 
primarily from top and W. 
Code 1003. 
   
 
flag   HiggsBSM:ffbar2H1Z   
 (default = off)
Scattering f fbar → h^0(H_1^0) Z^0 via s-channel 
Z^0 exchange. 
Code 1004. 
   
 
flag   HiggsBSM:ffbar2H1W   
 (default = off)
Scattering f fbar → h^0(H_1^0) W^+- via s-channel 
W^+- exchange. 
Code 1005. 
   
 
flag   HiggsBSM:ff2H1ff(t:ZZ)   
 (default = off)
Scattering f f' → h^0(H_1^0) f f' via Z^0 Z^0 fusion. 
Code 1006. 
   
 
flag   HiggsBSM:ff2H1ff(t:WW)   
 (default = off)
Scattering f_1 f_2 → h^0(H_1^0) f_3 f_4 via W^+ W^- 
fusion. 
Code 1007. 
   
 
flag   HiggsBSM:gg2H1ttbar   
 (default = off)
Scattering g g → h^0(H_1^0) t tbar via t tbar fusion 
(or, alternatively put, Higgs radiation off a top line). 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1008. 
   
 
flag   HiggsBSM:qqbar2H1ttbar   
 (default = off)
Scattering q qbar → h^0(H_1^0) t tbar via t tbar 
fusion (or, alternatively put, Higgs radiation off a top line). 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1009. 
   
 
2) H^0(H_2^0) processes
 
 
flag   HiggsBSM:allH2   
 (default = off)
Common switch for the group of H^0(H_2^0) production processes. 
   
 
flag   HiggsBSM:ffbar2H2   
 (default = off)
Scattering f fbar → H^0(H_2^0), where f sums over 
available flavours except top. 
Code 1021. 
   
 
flag   HiggsBSM:gg2H2   
 (default = off)
Scattering g g → H^0(H_2^0) via loop contributions primarily 
from top. 
Code 1022. 
   
 
flag   HiggsBSM:gmgm2H2   
 (default = off)
Scattering gamma gamma → H^0(H_2^0) via loop contributions 
primarily from top and W. 
Code 1023. 
   
 
flag   HiggsBSM:ffbar2H2Z   
 (default = off)
Scattering f fbar → H^0(H_2^0) Z^0 via s-channel 
Z^0 exchange. 
Code 1024. 
   
 
flag   HiggsBSM:ffbar2H2W   
 (default = off)
Scattering f fbar → H^0(H_2^0) W^+- via s-channel 
W^+- exchange. 
Code 1025. 
   
 
flag   HiggsBSM:ff2H2ff(t:ZZ)   
 (default = off)
Scattering f f' → H^0(H_2^0) f f' via Z^0 Z^0 fusion. 
Code 1026. 
   
 
flag   HiggsBSM:ff2H2ff(t:WW)   
 (default = off)
Scattering f_1 f_2 → H^0(H_2^0) f_3 f_4 via W^+ W^- 
fusion. 
Code 1027. 
   
 
flag   HiggsBSM:gg2H2ttbar   
 (default = off)
Scattering g g → H^0(H_2^0) t tbar via t tbar fusion 
(or, alternatively put, Higgs radiation off a top line). 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1028. 
   
 
flag   HiggsBSM:qqbar2H2ttbar   
 (default = off)
Scattering q qbar → H^0(H_2^0) t tbar via t tbar 
fusion (or, alternatively put, Higgs radiation off a top line). 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1029. 
   
 
3) A^0(H_3^0) processes
 
 
flag   HiggsBSM:allA3   
 (default = off)
Common switch for the group of A^0(H_3^0) production processes. 
   
 
flag   HiggsBSM:ffbar2A3   
 (default = off)
Scattering f fbar → A^0(H_3^0), where f sums over 
available flavours except top. 
Code 1041. 
   
 
flag   HiggsBSM:gg2A3   
 (default = off)
Scattering g g → A^0(A_3^0) via loop contributions primarily 
from top. 
Code 1042. 
   
 
flag   HiggsBSM:gmgm2A3   
 (default = off)
Scattering gamma gamma → A^0(A_3^0) via loop contributions 
primarily from top and W. 
Code 1043. 
   
 
flag   HiggsBSM:ffbar2A3Z   
 (default = off)
Scattering f fbar → A^0(A_3^0) Z^0 via s-channel 
Z^0 exchange. 
Code 1044. 
   
 
flag   HiggsBSM:ffbar2A3W   
 (default = off)
Scattering f fbar → A^0(A_3^0) W^+- via s-channel 
W^+- exchange. 
Code 1045. 
   
 
flag   HiggsBSM:ff2A3ff(t:ZZ)   
 (default = off)
Scattering f f' → A^0(A_3^0) f f' via Z^0 Z^0 fusion. 
Code 1046. 
   
 
flag   HiggsBSM:ff2A3ff(t:WW)   
 (default = off)
Scattering f_1 f_2 → A^0(A_3^0) f_3 f_4 via W^+ W^- 
fusion. Code 1047. 
   
 
flag   HiggsBSM:gg2A3ttbar   
 (default = off)
Scattering g g → A^0(A_3^0) t tbar via t tbar fusion 
(or, alternatively put, Higgs radiation off a top line). 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1048. 
   
 
flag   HiggsBSM:qqbar2A3ttbar   
 (default = off)
Scattering q qbar → A^0(A_3^0) t tbar via t tbar 
fusion (or, alternatively put, Higgs radiation off a top line). 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1049. 
   
 
4) H+- processes
 
 
flag   HiggsBSM:allH+-   
 (default = off)
Common switch for the group of H^+- production processes. 
   
 
flag   HiggsBSM:ffbar2H+-   
 (default = off)
Scattering f fbar' → H^+-, where f, fbar' sums over 
available incoming flavours. Since couplings are assumed 
generation-diagonal, in practice this means c sbar → H^+ 
and s cbar → H^-. 
Code 1061. 
   
 
flag   HiggsBSM:bg2H+-t   
 (default = off)
Scattering b g → H^+ tbar. At hadron colliders this is the 
dominant process for single-charged-Higgs production. 
Code 1062. 
   
 
5) Higgs-pair processes
 
 
flag   HiggsBSM:allHpair   
 (default = off)
Common switch for the group of Higgs pair-production processes. 
   
 
flag   HiggsBSM:ffbar2A3H1   
 (default = off)
Scattering f fbar → A^0(H_3) h^0(H_1). 
Code 1081. 
   
 
flag   HiggsBSM:ffbar2A3H2   
 (default = off)
Scattering f fbar → A^0(H_3) H^0(H_2). 
Code 1082. 
   
 
flag   HiggsBSM:ffbar2H+-H1   
 (default = off)
Scattering f fbar → H^+- h^0(H_1). 
Code 1083. 
   
 
flag   HiggsBSM:ffbar2H+-H2   
 (default = off)
Scattering f fbar → H^+- H^0(H_2). 
Code 1084. 
   
 
flag   HiggsBSM:ffbar2H+H-   
 (default = off)
Scattering f fbar → H+ H-. 
Code 1085. 
   
 
 
Beyond-the-Standard-Model Higgs, further processes
 
 
This section mimics the above section on "Standard-Model Higgs, 
further processes", i.e. it contains higher-order corrections 
to the processes already listed. The two sets therefore could not 
be used simultaneously without unphysical double-counting. 
They are not controlled by any group flag, but have to be switched 
on for each separate process after due consideration. We refer to 
the standard-model description for a set of further comments on 
the processes. 
 
1) h^0(H_1^0) processes
 
 
flag   HiggsBSM:qg2H1q   
 (default = off)
Scattering q g → h^0 q. This process gives first-order 
corrections to the f fbar → h^0 one above, and should only be 
used to study  the high-pT tail, while f fbar → h^0 
should be used for inclusive production. Only the dominant c 
and b contributions are included, and generated separately 
for technical reasons. Note that another first-order process would be 
q qbar → h^0 g, which is not explicitly implemented here, 
but is obtained from showering off the lowest-order process. It does not 
contain any b at large pT, however, so is less 
interesting for many applications. 
Code 1011. 
   
 
flag   HiggsBSM:gg2H1bbbar   
 (default = off)
Scattering g g → h^0 b bbar. This process is yet one order 
higher of the b bbar → h^0 and b g → h^0 b chain, 
where now two quarks should be required above some large pT 
threshold. 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1012. 
   
 
flag   HiggsBSM:qqbar2H1bbbar   
 (default = off)
Scattering q qbar → h^0 b bbar via an s-channel 
gluon, so closely related to the previous one, but typically less 
important owing to the smaller rate of (anti)quarks relative to 
gluons. 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1013. 
   
 
flag   HiggsBSM:gg2H1g(l:t)   
 (default = off)
Scattering g g → h^0 g via loop contributions primarily 
from top. 
Code 1014. 
   
 
flag   HiggsBSM:qg2H1q(l:t)   
 (default = off)
Scattering q g → h^0 q via loop contributions primarily 
from top. Not to be confused with the HiggsBSM:qg2H1q 
process above, with its direct fermion-to-Higgs coupling. 
Code 1015. 
   
 
flag   HiggsBSM:qqbar2H1g(l:t)   
 (default = off)
Scattering q qbar → h^0 g via an s-channel gluon 
and loop contributions primarily from top. Is strictly speaking a 
"new" process, not directly derived from g g → h^0, and 
could therefore be included in the standard mix without double-counting, 
but is numerically negligible. 
Code 1016. 
   
 
2) H^0(H_2^0) processes
 
 
flag   HiggsBSM:qg2H2q   
 (default = off)
Scattering q g → H^0 q. This process gives first-order 
corrections to the f fbar → H^0 one above, and should only be 
used to study  the high-pT tail, while f fbar → H^0 
should be used for inclusive production. Only the dominant c 
and b contributions are included, and generated separately 
for technical reasons. Note that another first-order process would be 
q qbar → H^0 g, which is not explicitly implemented here, 
but is obtained from showering off the lowest-order process. It does not 
contain any b at large pT, however, so is less 
interesting for many applications. 
Code 1031. 
   
 
flag   HiggsBSM:gg2H2bbbar   
 (default = off)
Scattering g g → H^0 b bbar. This process is yet one order 
higher of the b bbar → H^0 and b g → H^0 b chain, 
where now two quarks should be required above some large pT 
threshold. 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1032. 
   
 
flag   HiggsBSM:qqbar2H2bbbar   
 (default = off)
Scattering q qbar → H^0 b bbar via an s-channel 
gluon, so closely related to the previous one, but typically less 
important owing to the smaller rate of (anti)quarks relative to 
gluons. 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1033. 
   
 
flag   HiggsBSM:gg2H2g(l:t)   
 (default = off)
Scattering g g → H^0 g via loop contributions primarily 
from top. 
Code 1034. 
   
 
flag   HiggsBSM:qg2H2q(l:t)   
 (default = off)
Scattering q g → H^0 q via loop contributions primarily 
from top. Not to be confused with the HiggsBSM:qg2H1q 
process above, with its direct fermion-to-Higgs coupling. 
Code 1035. 
   
 
flag   HiggsBSM:qqbar2H2g(l:t)   
 (default = off)
Scattering q qbar → H^0 g via an s-channel gluon 
and loop contributions primarily from top. Is strictly speaking a 
"new" process, not directly derived from g g → H^0, and 
could therefore be included in the standard mix without double-counting, 
but is numerically negligible. 
Code 1036. 
   
 
3) A^0(H_3^0) processes
 
 
flag   HiggsBSM:qg2A3q   
 (default = off)
Scattering q g → A^0 q. This process gives first-order 
corrections to the f fbar → A^0 one above, and should only be 
used to study  the high-pT tail, while f fbar → A^0 
should be used for inclusive production. Only the dominant c 
and b contributions are included, and generated separately 
for technical reasons. Note that another first-order process would be 
q qbar → A^0 g, which is not explicitly implemented here, 
but is obtained from showering off the lowest-order process. It does not 
contain any b at large pT, however, so is less 
interesting for many applications. 
Code 1051. 
   
 
flag   HiggsBSM:gg2A3bbbar   
 (default = off)
Scattering g g → A^0 b bbar. This process is yet one order 
higher of the b bbar → A^0 and b g → A^0 b chain, 
where now two quarks should be required above some large pT 
threshold. 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1052. 
   
 
flag   HiggsBSM:qqbar2A3bbbar   
 (default = off)
Scattering q qbar → A^0 b bbar via an s-channel 
gluon, so closely related to the previous one, but typically less 
important owing to the smaller rate of (anti)quarks relative to 
gluons. 
Warning: unfortunately this process is rather slow, owing to a 
lengthy cross-section expression and inefficient phase-space selection. 
Code 1053. 
   
 
flag   HiggsBSM:gg2A3g(l:t)   
 (default = off)
Scattering g g → A^0 g via loop contributions primarily 
from top. 
Code 1054. 
   
 
flag   HiggsBSM:qg2A3q(l:t)   
 (default = off)
Scattering q g → A^0 q via loop contributions primarily 
from top. Not to be confused with the HiggsBSM:qg2H1q 
process above, with its direct fermion-to-Higgs coupling. 
Code 1055. 
   
 
flag   HiggsBSM:qqbar2A3g(l:t)   
 (default = off)
Scattering q qbar → A^0 g via an s-channel gluon 
and loop contributions primarily from top. Is strictly speaking a 
"new" process, not directly derived from g g → A^0, and 
could therefore be included in the standard mix without double-counting, 
but is numerically negligible. 
Code 1056. 
   
 
 
Parameters for Beyond-the-Standard-Model Higgs production and decay
 
 
This section offers a big flexibility to set couplings of the various 
Higgs states to fermions and gauge bosons, and also to each other. 
The intention is that, for scenarios like MSSM, you should use standard 
input from the SUSY Les Houches 
Accord, rather than having to set it all yourself. In other cases, 
however, the freedom is there for you to use. Kindly note that some 
of the internal calculations of partial widths from the parameters provided 
do not include mixing between the scalar and pseudoscalar states. 
 
 
Masses would be set in the ParticleData database, 
while couplings are set below. When possible, the couplings of the Higgs 
states are normalized to the corresponding coupling within the SM. 
When not, their values within the MSSM are indicated, from which 
it should be straightforward to understand what to use instead. 
The exception is some couplings that vanish also in the MSSM, where the 
normalization has been defined in close analogy with nonvanishing ones. 
Some parameter names are asymmetric but crossing can always be used, 
i.e. the coupling for A^0 → H^0 Z^0 obviously is also valid 
for H^0 → A^0 Z^0 and Z^0 → H^0 A^0. 
Note that couplings usually appear quadratically in matrix elements. 
 
parm   HiggsH1:coup2d   
 (default = 1.)
The h^0(H_1^0) coupling to down-type quarks. 
   
 
parm   HiggsH1:coup2u   
 (default = 1.)
The h^0(H_1^0) coupling to up-type quarks. 
   
 
parm   HiggsH1:coup2l   
 (default = 1.)
The h^0(H_1^0) coupling to (charged) leptons. 
   
 
parm   HiggsH1:coup2Z   
 (default = 1.)
The h^0(H_1^0) coupling to Z^0. 
   
 
parm   HiggsH1:coup2W   
 (default = 1.)
The h^0(H_1^0) coupling to W^+-. 
   
 
parm   HiggsH1:coup2Hchg   
 (default = 0.)
The h^0(H_1^0) coupling to H^+- (in loops). 
Is sin(beta - alpha) + cos(2 beta) sin(beta + alpha) / 
(2 cos^2theta_W) in the MSSM. 
   
 
parm   HiggsH2:coup2d   
 (default = 1.)
The H^0(H_2^0) coupling to down-type quarks. 
   
 
parm   HiggsH2:coup2u   
 (default = 1.)
The H^0(H_2^0) coupling to up-type quarks. 
   
 
parm   HiggsH2:coup2l   
 (default = 1.)
The H^0(H_2^0) coupling to (charged) leptons. 
   
 
parm   HiggsH2:coup2Z   
 (default = 1.)
The H^0(H_2^0) coupling to Z^0. 
   
 
parm   HiggsH2:coup2W   
 (default = 1.)
The H^0(H_2^0) coupling to W^+-. 
   
 
parm   HiggsH2:coup2Hchg   
 (default = 0.)
The H^0(H_2^0) coupling to H^+- (in loops). 
Is cos(beta - alpha) + cos(2 beta) cos(beta + alpha) / 
(2 cos^2theta_W) in the MSSM. 
   
 
parm   HiggsH2:coup2H1H1   
 (default = 1.)
The H^0(H_2^0) coupling to a h^0(H_1^0) pair. 
Is cos(2 alpha) cos(beta + alpha) - 2 sin(2 alpha) 
sin(beta + alpha) in the MSSM. 
   
 
parm   HiggsH2:coup2A3A3   
 (default = 1.)
The H^0(H_2^0) coupling to an A^0(H_3^0) pair. 
Is cos(2 beta) cos(beta + alpha) in the MSSM. 
   
 
parm   HiggsH2:coup2H1Z   
 (default = 0.)
The H^0(H_2^0) coupling to a h^0(H_1^0) Z^0 pair. 
Vanishes in the MSSM. 
   
 
parm   HiggsH2:coup2A3H1   
 (default = 0.)
The H^0(H_2^0) coupling to an A^0(H_3^0) h^0(H_1^0) pair. 
Vanishes in the MSSM. 
   
 
parm   HiggsH2:coup2HchgW   
 (default = 0.)
The H^0(H_2^0) coupling to a H^+- W-+ pair. 
Is sin(beta - alpha) in the MSSM. 
   
 
parm   HiggsA3:coup2d   
 (default = 1.)
The A^0(H_3^0) coupling to down-type quarks. 
   
 
parm   HiggsA3:coup2u   
 (default = 1.)
The A^0(H_3^0) coupling to up-type quarks. 
   
 
parm   HiggsA3:coup2l   
 (default = 1.)
The A^0(H_3^0) coupling to (charged) leptons. 
   
 
parm   HiggsA3:coup2H1Z   
 (default = 1.)
The A^0(H_3^0) coupling to a h^0(H_1^0) Z^0 pair. 
Is cos(beta - alpha) in the MSSM. 
   
 
parm   HiggsA3:coup2H2Z   
 (default = 1.)
The A^0(H_3^0) coupling to a H^0(H_2^0) Z^0 pair. 
Is sin(beta - alpha) in the MSSM. 
   
 
parm   HiggsA3:coup2Z   
 (default = 0.)
The A^0(H_3^0) coupling to Z^0. 
Vanishes in the MSSM. 
   
 
parm   HiggsA3:coup2W   
 (default = 0.)
The A^0(H_3^0) coupling to W^+-. 
Vanishes in the MSSM. 
   
 
parm   HiggsA3:coup2H1H1   
 (default = 0.)
The A^0(H_3^0) coupling to a h^0(H_1^0) pair. 
Vanishes in the MSSM. 
   
 
parm   HiggsA3:coup2Hchg   
 (default = 0.)
The A^0(H_3^0) coupling to H^+-. 
Vanishes in the MSSM. 
   
 
parm   HiggsA3:coup2HchgW   
 (default = 1.)
The A^0(H_3^0) coupling to a H^+- W-+ pair. 
Is 1 in the MSSM. 
   
 
parm   HiggsHchg:tanBeta   
 (default = 5.)
The tan(beta) value, which leads to an enhancement of the 
H^+- coupling to down-type fermions and suppression to 
up-type ones. The same angle also appears in many other places, 
but this particular parameter is only used for the charged-Higgs case. 
   
 
parm   HiggsHchg:coup2H1W   
 (default = 1.)
The H^+- coupling to a h^0(H_1^0) W^+- pair. 
Is cos(beta - alpha) in the MSSM. 
   
 
parm   HiggsHchg:coup2H2W   
 (default = 0.)
The H^+- coupling to a H^0(H_2^0) W^+- pair. 
Is sin(beta - alpha) in the MSSM. 
   
 
 
Another set of parameters are not used in the production stage but 
exclusively for the description of angular distributions in decays. 
 
mode   HiggsH1:parity   
 (default = 1; minimum = 0; maximum = 4)
possibility to modify angular decay correlations in the decay of a 
h^0(H_1) decay Z^0 Z^0 or W^+ W^- to four 
fermions, or tau^+ tau^- to any final state. Currently it 
does not affect the partial width of the channels, which is only based 
on the above parameters. 
option  0 : isotropic decays.   
option  1 : assuming the h^0(H_1) is a pure scalar 
(CP-even), as in the MSSM.   
option  2 : assuming the h^0(H_1) is a pure pseudoscalar 
(CP-odd).   
option  3 : assuming the h^0(H_1) is a mixture of the two, 
including the CP-violating interference term. The parameter 
eta, see below, sets the strength of the CP-odd admixture, 
with the interference term being proportional to eta 
and the CP-odd one to eta^2. Intended for decays into 
W^+ W^- or Z^0 Z^0.   
option  4 : same as 3 but now phi, see 
below, sets the CP-mixing angle. The CP-even term is proportional 
to sin^2(phi), the interference to sin(phi)cos(phi), 
and the CP-odd term to cos^2(phi). Consequently phi=0 is 
pure CP-odd and phi=pi/2 is pure CP-even. Intended for decays 
of h -> f fbar, notably for tau lepton polarization, 
whereas W^+ W^- and Z^0 Z^0 decays are isotropic. 
   
   
 
parm   HiggsH1:etaParity   
 (default = 0.)
The eta value of CP-violation in the 
HiggsH1:parity = 3 option. 
   
 
parm   HiggsH1:phiParity   
 (default = 0.)
The phi value of CP-mixing in the 
HiggsH1:parity = 4 option. 
   
 
mode   HiggsH2:parity   
 (default = 1; minimum = 0; maximum = 4)
possibility to modify angular decay correlations in the decay of a 
H^0(H_2) decay Z^0 Z^0 or W^+ W^- to four 
fermions, or tau^+ tau^- to any final state. Currently it 
does not affect the partial width of the channels, which is only based 
on the above parameters. 
option  0 : isotropic decays.   
option  1 : assuming the H^0(H_2) is a pure scalar 
(CP-even), as in the MSSM.   
option  2 : assuming the H^0(H_2) is a pure pseudoscalar 
(CP-odd).   
option  3 : assuming the H^0(H_2) is a mixture of the two, 
including the CP-violating interference term. The parameter 
eta, see below, sets the strength of the CP-odd admixture, 
with the interference term being proportional to eta 
and the CP-odd one to eta^2. Intended or decays into 
W^+ W^- or Z^0 Z^0.   
option  4 : same as 3 but now phi, see 
below, sets the CP-mixing angle. The CP-even term is proportional 
to sin^2(phi), the interference to sin(phi)cos(phi), 
and the CP-odd term to cos^2(phi). Consequently phi=0 is 
pure CP-odd and phi=pi/2 is pure CP-even. Intended for decays 
of H -> f fbar, notably for tau lepton polarization, 
whereas W^+ W^- and Z^0 Z^0 decays are isotropic. 
   
   
 
parm   HiggsH2:etaParity   
 (default = 0.)
The eta value of CP-violation in the 
HiggsH2:parity = 3 option. 
   
 
parm   HiggsH2:phiParity   
 (default = 0.)
The phi value of CP-mixing in the 
HiggsH2:parity = 4 option. 
   
 
mode   HiggsA3:parity   
 (default = 2; minimum = 0; maximum = 4)
possibility to modify angular decay correlations in the decay of a 
A^0(H_3) decay Z^0 Z^0 or W^+ W^- to four 
fermions, or tau^+ tau^- to any final state. Currently it 
does not affect the partial width of the channels, which is only based 
on the above parameters. 
option  0 : isotropic decays.   
option  1 : assuming the A^0(H_3) is a pure scalar 
(CP-even).   
option  2 : assuming the A^0(H_3) is a pure pseudoscalar 
(CP-odd), as in the MSSM.   
option  3 : assuming the A^0(H_3) is a mixture of the two, 
including the CP-violating interference term. The parameter 
eta, see below, sets the strength of the CP-odd admixture, 
with the interference term being proportional to eta 
and the CP-odd one to eta^2. Intended for decays into 
W^+ W^- or Z^0 Z^0.   
option  4 : same as 3 but now phi, see 
below, sets the CP-mixing angle. The CP-even term is proportional 
to sin^2(phi), the interference to sin(phi)cos(phi), 
and the CP-odd term to cos^2(phi). Consequently phi=0 is 
pure CP-odd and phi=pi/2 is pure CP-even. Intended for decays 
of A -> f fbar, notably for tau lepton polarization, 
whereas W^+ W^- and Z^0 Z^0 decays are isotropic. 
   
   
 
parm   HiggsA3:etaParity   
 (default = 0.)
The eta value of CP-violation in the 
HiggsA3:parity = 3 option. 
   
 
parm   HiggsA3:phiParity   
 (default = 0.)
The phi value of CP-mixing in the 
HiggsA3:parity = 4 option.