<html> <head> <title>Higgs Processes</title> <link rel="stylesheet" type="text/css" href="pythia.css"/> <link rel="shortcut icon" href="pythia32.gif"/> </head> <body> <h2>Higgs Processes</h2> 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. Three choices can be made irrespective of the particular model: <p/><code>flag </code><strong> Higgs:cubicWidth </strong> (<code>default = <strong>off</strong></code>)<br/> The partial width of a Higgs particle to a pair of gauge bosons, <i>W^+ W^-</i> or <i>Z^0 Z^0</i>, depends cubically on the Higgs mass. When selecting the Higgs according to a Breit-Wigner, so that the actual mass <i>mHat</i> does not agree with the nominal <i>m_Higgs</i> one, an ambiguity arises which of the two to use [<a href="Bibliography.html" target="page">Sey95</a>]. The default is to use a linear dependence on <i>mHat</i>, i.e. a width proportional to <i>m_Higgs^2 * mHat</i>, while <code>on</code> gives a <i>mHat^3</i> dependence. This does not affect the widths to fermions, which only depend linearly on <i>mHat</i>. This flag is used both for SM and BSM Higgs bosons. <p/><code>flag </code><strong> Higgs:runningLoopMass </strong> (<code>default = <strong>on</strong></code>)<br/> The partial width of a Higgs particle to a pair of gluons or photons, or a <i>gamma Z^0</i> pair, proceeds in part through quark loops, mainly <i>b</i> and <i>t</i>. 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.) <p/><code>flag </code><strong> Higgs:clipWings </strong> (<code>default = <strong>on</strong></code>)<br/> 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 <code>Higgs:wingsFac</code> value is used to cut away the wings. <br/><b>Warning:</b> 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 <code>id:mMin</code> and <code>id:mMax</code> values should therefore be reset (e.g. to the defaults 50. and 0.) when <code>id:m0</code> is changed. <p/><code>parm </code><strong> Higgs:wingsFac </strong> (<code>default = <strong>50.</strong></code>; <code>minimum = 0.</code>)<br/> With <code>Higgs:clipWings</code> on, all Higgs masses which deviate from the nominal one by more than <code>Higgs:wingsFac</code> times the nominal width are forbidden. This is achieved by setting the <code>mMin</code> and <code>mMax</code> 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. <h3>Standard-Model Higgs, basic processes</h3> 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 <code>ParticleData</code> database; thereafter the properties within the SM are essentially fixed. <p/><code>flag </code><strong> HiggsSM:all </strong> (<code>default = <strong>off</strong></code>)<br/> Common switch for the group of Higgs production within the Standard Model. <p/><code>flag </code><strong> HiggsSM:ffbar2H </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H^0</i>, where <i>f</i> 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. <p/><code>flag </code><strong> HiggsSM:gg2H </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> H^0</i> via loop contributions primarily from top. Code 902. <p/><code>flag </code><strong> HiggsSM:gmgm2H </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>gamma gamma -> H^0</i> via loop contributions primarily from top and <i>W</i>. Code 903. <p/><code>flag </code><strong> HiggsSM:ffbar2HZ </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H^0 Z^0</i> via <i>s</i>-channel <i>Z^0</i> exchange. Code 904. <p/><code>flag </code><strong> HiggsSM:ffbar2HW </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H^0 W^+-</i> via <i>s</i>-channel <i>W^+-</i> exchange. Code 905. <p/><code>flag </code><strong> HiggsSM:ff2Hff(t:ZZ) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f f' -> H^0 f f'</i> via <i>Z^0 Z^0</i> fusion. Code 906. <p/><code>flag </code><strong> HiggsSM:ff2Hff(t:WW) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f_1 f_2 -> H^0 f_3 f_4</i> via <i>W^+ W^-</i> fusion. Code 907. <p/><code>flag </code><strong> HiggsSM:gg2Httbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> H^0 t tbar</i> via <i>t tbar</i> 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. <p/><code>flag </code><strong> HiggsSM:qqbar2Httbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> H^0 t tbar</i> via <i>t tbar</i> 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. <h3>Standard-Model Higgs, further processes</h3> A number of further production processes has been implemented, that are specializations of some of the above ones to the high-<i>pT</i> region. The sets therefore could not be used simultaneously without unphysical double-counting, as further explained below. They are not switched on by the <code>HiggsSM:all</code> flag, but have to be switched on for each separate process after due consideration. <p/> The first three processes in this section are related to the Higgs point coupling to fermions, and so primarily are of interest for <i>b</i> quarks. It is here useful to begin by reminding that a process like <i>b bbar -> H^0</i> implies that a <i>b/bbar</i> is taken from each incoming hadron, leaving behind its respective antiparticle. The initial-state showers will then add one <i>g -> b bbar</i> branching on either side, so that effectively the process becomes <i>g g -> H0 b bbar</i>. This would be the same basic process as the <i>g g -> H^0 t tbar</i> 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 <i>H^0 t tbar</i> subsystem. By contrast, owing to the <i>b</i> being much lighter than the Higgs, multiple gluon emissions must be resummed for <i>b</i>, as is done by PDF's and showers, in order to obtain a sensible description of the total production rate, when the <i>b</i> quarks predominantly are produced at small <i>pT</i> values. <p/><code>flag </code><strong> HiggsSM:qg2Hq </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q g -> H^0 q</i>. This process gives first-order corrections to the <i>f fbar -> H^0</i> one above, and should only be used to study the high-<i>pT</i> tail, while <i>f fbar -> H^0</i> should be used for inclusive production. Only the dominant <i>c</i> and <i>b</i> contributions are included, and generated separately for technical reasons. Note that another first-order process would be <i>q qbar -> H^0 g</i>, which is not explicitly implemented here, but is obtained from showering off the lowest-order process. It does not contain any <i>b</i> at large <i>pT</i>, however, so is less interesting for many applications. Code 911. <p/><code>flag </code><strong> HiggsSM:gg2Hbbbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> H^0 b bbar</i>. This process is yet one order higher of the <i>b bbar -> H^0</i> and <i>b g -> H^0 b</i> chain, where now two quarks should be required above some large <i>pT</i> threshold. Warning: unfortunately this process is rather slow, owing to a lengthy cross-section expression and inefficient phase-space selection. Code 912. <p/><code>flag </code><strong> HiggsSM:qqbar2Hbbbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> H^0 b bbar</i> via an <i>s</i>-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. <p/> The second set of processes are predominantly first-order corrections to the <i>g g -> H^0</i> 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 <i>g g -> H^0</i>. (Complete loop expressions are available e.g. in PYTHIA 6.4 but are very lengthy.) This provides a reasonably accurate description for "intermediate" <i>pT</i> values, but fails when the <i>pT</i> scale approaches the top mass. <p/><code>flag </code><strong> HiggsSM:gg2Hg(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> H^0 g</i> via loop contributions primarily from top. Code 914. <p/><code>flag </code><strong> HiggsSM:qg2Hq(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q g -> H^0 q</i> via loop contributions primarily from top. Not to be confused with the <code>HiggsSM:qg2Hq</code> process above, with its direct fermion-to-Higgs coupling. Code 915. <p/><code>flag </code><strong> HiggsSM:qqbar2Hg(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> H^0 g</i> via an <i>s</i>-channel gluon and loop contributions primarily from top. Is strictly speaking a "new" process, not directly derived from <i>g g -> H^0</i>, and could therefore be included in the standard mix without double-counting, but is numerically negligible. Code 916. <h3>Beyond-the-Standard-Model Higgs, introduction</h3> 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 <i>h^0, H^0, A^0</i> and <i>H^+-</i>. If the scalar and pseudocalar states mix the resulting states are labeled <i>H_1^0, H_2^0, H_3^0</i>. In process names and parameter explanations both notations will be used, but for settings labels we have adapted the shorthand hybrid notation <code>H1</code> for <i>h^0(H_1^0)</i>, <code>H2</code> for <i>H^0(H_2^0)</i> and <code>A3</code> for <i>A^0(H_3^0)</i>. (Recall that the <code>Settings</code> 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 <i>h^0</i> vs. <i>H^0</i>.) We leave the issue of mass ordering between <i>H^0</i> and <i>A^0</i> open, and thereby also that of <i>H_2^0</i> and <i>H_3^0</i>. <p/><code>flag </code><strong> Higgs:useBSM </strong> (<code>default = <strong>off</strong></code>)<br/> 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. <h3>Beyond-the-Standard-Model Higgs, basic processes</h3> 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 <i>A^0</i>, but are kept for flexibility in cases of mixing with the scalar <i>h^0</i> and <i>H^0</i> 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 <i>q qbar -> A^0 Z^0</i>, which otherwise is forbidden. However, note that the loop integrals e.g. for <i>g g -> h^0/H^0/A^0</i> 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. <p/><code>flag </code><strong> HiggsBSM:all </strong> (<code>default = <strong>off</strong></code>)<br/> Common switch for the group of Higgs production beyond the Standard Model, as listed below. <h4>1) <i>h^0(H_1^0)</i> processes</h4> <p/><code>flag </code><strong> HiggsBSM:allH1 </strong> (<code>default = <strong>off</strong></code>)<br/> Common switch for the group of <i>h^0(H_1^0)</i> production processes. <p/><code>flag </code><strong> HiggsBSM:ffbar2H1 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> h^0(H_1^0)</i>, where <i>f</i> sums over available flavours except top. Code 1001. <p/><code>flag </code><strong> HiggsBSM:gg2H1 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> h^0(H_1^0)</i> via loop contributions primarily from top. Code 1002. <p/><code>flag </code><strong> HiggsBSM:gmgm2H1 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>gamma gamma -> h^0(H_1^0)</i> via loop contributions primarily from top and <i>W</i>. Code 1003. <p/><code>flag </code><strong> HiggsBSM:ffbar2H1Z </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> h^0(H_1^0) Z^0</i> via <i>s</i>-channel <i>Z^0</i> exchange. Code 1004. <p/><code>flag </code><strong> HiggsBSM:ffbar2H1W </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> h^0(H_1^0) W^+-</i> via <i>s</i>-channel <i>W^+-</i> exchange. Code 1005. <p/><code>flag </code><strong> HiggsBSM:ff2H1ff(t:ZZ) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f f' -> h^0(H_1^0) f f'</i> via <i>Z^0 Z^0</i> fusion. Code 1006. <p/><code>flag </code><strong> HiggsBSM:ff2H1ff(t:WW) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f_1 f_2 -> h^0(H_1^0) f_3 f_4</i> via <i>W^+ W^-</i> fusion. Code 1007. <p/><code>flag </code><strong> HiggsBSM:gg2H1ttbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> h^0(H_1^0) t tbar</i> via <i>t tbar</i> 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. <p/><code>flag </code><strong> HiggsBSM:qqbar2H1ttbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> h^0(H_1^0) t tbar</i> via <i>t tbar</i> 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. <h4>2) <i>H^0(H_2^0)</i> processes</h4> <p/><code>flag </code><strong> HiggsBSM:allH2 </strong> (<code>default = <strong>off</strong></code>)<br/> Common switch for the group of <i>H^0(H_2^0)</i> production processes. <p/><code>flag </code><strong> HiggsBSM:ffbar2H2 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H^0(H_2^0)</i>, where <i>f</i> sums over available flavours except top. Code 1021. <p/><code>flag </code><strong> HiggsBSM:gg2H2 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> H^0(H_2^0)</i> via loop contributions primarily from top. Code 1022. <p/><code>flag </code><strong> HiggsBSM:gmgm2H2 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>gamma gamma -> H^0(H_2^0)</i> via loop contributions primarily from top and <i>W</i>. Code 1023. <p/><code>flag </code><strong> HiggsBSM:ffbar2H2Z </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H^0(H_2^0) Z^0</i> via <i>s</i>-channel <i>Z^0</i> exchange. Code 1024. <p/><code>flag </code><strong> HiggsBSM:ffbar2H2W </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H^0(H_2^0) W^+-</i> via <i>s</i>-channel <i>W^+-</i> exchange. Code 1025. <p/><code>flag </code><strong> HiggsBSM:ff2H2ff(t:ZZ) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f f' -> H^0(H_2^0) f f'</i> via <i>Z^0 Z^0</i> fusion. Code 1026. <p/><code>flag </code><strong> HiggsBSM:ff2H2ff(t:WW) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f_1 f_2 -> H^0(H_2^0) f_3 f_4</i> via <i>W^+ W^-</i> fusion. Code 1027. <p/><code>flag </code><strong> HiggsBSM:gg2H2ttbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> H^0(H_2^0) t tbar</i> via <i>t tbar</i> 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. <p/><code>flag </code><strong> HiggsBSM:qqbar2H2ttbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> H^0(H_2^0) t tbar</i> via <i>t tbar</i> 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. <h4>3) <i>A^0(H_3^0)</i> processes</h4> <p/><code>flag </code><strong> HiggsBSM:allA3 </strong> (<code>default = <strong>off</strong></code>)<br/> Common switch for the group of <i>A^0(H_3^0)</i> production processes. <p/><code>flag </code><strong> HiggsBSM:ffbar2A3 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> A^0(H_3^0)</i>, where <i>f</i> sums over available flavours except top. Code 1041. <p/><code>flag </code><strong> HiggsBSM:gg2A3 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> A^0(A_3^0)</i> via loop contributions primarily from top. Code 1042. <p/><code>flag </code><strong> HiggsBSM:gmgm2A3 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>gamma gamma -> A^0(A_3^0)</i> via loop contributions primarily from top and <i>W</i>. Code 1043. <p/><code>flag </code><strong> HiggsBSM:ffbar2A3Z </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> A^0(A_3^0) Z^0</i> via <i>s</i>-channel <i>Z^0</i> exchange. Code 1044. <p/><code>flag </code><strong> HiggsBSM:ffbar2A3W </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> A^0(A_3^0) W^+-</i> via <i>s</i>-channel <i>W^+-</i> exchange. Code 1045. <p/><code>flag </code><strong> HiggsBSM:ff2A3ff(t:ZZ) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f f' -> A^0(A_3^0) f f'</i> via <i>Z^0 Z^0</i> fusion. Code 1046. <p/><code>flag </code><strong> HiggsBSM:ff2A3ff(t:WW) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f_1 f_2 -> A^0(A_3^0) f_3 f_4</i> via <i>W^+ W^-</i> fusion. Code 1047. <p/><code>flag </code><strong> HiggsBSM:gg2A3ttbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> A^0(A_3^0) t tbar</i> via <i>t tbar</i> 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. <p/><code>flag </code><strong> HiggsBSM:qqbar2A3ttbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> A^0(A_3^0) t tbar</i> via <i>t tbar</i> 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. <h4>4) <i>H+-</i> processes</h4> <p/><code>flag </code><strong> HiggsBSM:allH+- </strong> (<code>default = <strong>off</strong></code>)<br/> Common switch for the group of <i>H^+-</i> production processes. <p/><code>flag </code><strong> HiggsBSM:ffbar2H+- </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar' -> H^+-</i>, where <i>f, fbar'</i> sums over available incoming flavours. Since couplings are assumed generation-diagonal, in practice this means <i>c sbar -> H^+</i> and <i>s cbar -> H^-</i>. Code 1061. <p/><code>flag </code><strong> HiggsBSM:bg2H+-t </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>b g -> H^+ tbar</i>. At hadron colliders this is the dominant process for single-charged-Higgs production. Code 1062. <h4>5) Higgs-pair processes</h4> <p/><code>flag </code><strong> HiggsBSM:allHpair </strong> (<code>default = <strong>off</strong></code>)<br/> Common switch for the group of Higgs pair-production processes. <p/><code>flag </code><strong> HiggsBSM:ffbar2A3H1 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> A^0(H_3) h^0(H_1)</i>. Code 1081. <p/><code>flag </code><strong> HiggsBSM:ffbar2A3H2 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> A^0(H_3) H^0(H_2)</i>. Code 1082. <p/><code>flag </code><strong> HiggsBSM:ffbar2H+-H1 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H^+- h^0(H_1)</i>. Code 1083. <p/><code>flag </code><strong> HiggsBSM:ffbar2H+-H2 </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H^+- H^0(H_2)</i>. Code 1084. <p/><code>flag </code><strong> HiggsBSM:ffbar2H+H- </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>f fbar -> H+ H-</i>. Code 1085. <h3>Beyond-the-Standard-Model Higgs, further processes</h3> 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. <h4>1) <i>h^0(H_1^0)</i> processes</h4> <p/><code>flag </code><strong> HiggsBSM:qg2H1q </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q g -> h^0 q</i>. This process gives first-order corrections to the <i>f fbar -> h^0</i> one above, and should only be used to study the high-<i>pT</i> tail, while <i>f fbar -> h^0</i> should be used for inclusive production. Only the dominant <i>c</i> and <i>b</i> contributions are included, and generated separately for technical reasons. Note that another first-order process would be <i>q qbar -> h^0 g</i>, which is not explicitly implemented here, but is obtained from showering off the lowest-order process. It does not contain any <i>b</i> at large <i>pT</i>, however, so is less interesting for many applications. Code 1011. <p/><code>flag </code><strong> HiggsBSM:gg2H1bbbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> h^0 b bbar</i>. This process is yet one order higher of the <i>b bbar -> h^0</i> and <i>b g -> h^0 b</i> chain, where now two quarks should be required above some large <i>pT</i> threshold. Warning: unfortunately this process is rather slow, owing to a lengthy cross-section expression and inefficient phase-space selection. Code 1012. <p/><code>flag </code><strong> HiggsBSM:qqbar2H1bbbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> h^0 b bbar</i> via an <i>s</i>-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. <p/><code>flag </code><strong> HiggsBSM:gg2H1g(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> h^0 g</i> via loop contributions primarily from top. Code 1014. <p/><code>flag </code><strong> HiggsBSM:qg2H1q(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q g -> h^0 q</i> via loop contributions primarily from top. Not to be confused with the <code>HiggsBSM:qg2H1q</code> process above, with its direct fermion-to-Higgs coupling. Code 1015. <p/><code>flag </code><strong> HiggsBSM:qqbar2H1g(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> h^0 g</i> via an <i>s</i>-channel gluon and loop contributions primarily from top. Is strictly speaking a "new" process, not directly derived from <i>g g -> h^0</i>, and could therefore be included in the standard mix without double-counting, but is numerically negligible. Code 1016. <h4>2) <i>H^0(H_2^0)</i> processes</h4> <p/><code>flag </code><strong> HiggsBSM:qg2H2q </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q g -> H^0 q</i>. This process gives first-order corrections to the <i>f fbar -> H^0</i> one above, and should only be used to study the high-<i>pT</i> tail, while <i>f fbar -> H^0</i> should be used for inclusive production. Only the dominant <i>c</i> and <i>b</i> contributions are included, and generated separately for technical reasons. Note that another first-order process would be <i>q qbar -> H^0 g</i>, which is not explicitly implemented here, but is obtained from showering off the lowest-order process. It does not contain any <i>b</i> at large <i>pT</i>, however, so is less interesting for many applications. Code 1031. <p/><code>flag </code><strong> HiggsBSM:gg2H2bbbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> H^0 b bbar</i>. This process is yet one order higher of the <i>b bbar -> H^0</i> and <i>b g -> H^0 b</i> chain, where now two quarks should be required above some large <i>pT</i> threshold. Warning: unfortunately this process is rather slow, owing to a lengthy cross-section expression and inefficient phase-space selection. Code 1032. <p/><code>flag </code><strong> HiggsBSM:qqbar2H2bbbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> H^0 b bbar</i> via an <i>s</i>-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. <p/><code>flag </code><strong> HiggsBSM:gg2H2g(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> H^0 g</i> via loop contributions primarily from top. Code 1034. <p/><code>flag </code><strong> HiggsBSM:qg2H2q(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q g -> H^0 q</i> via loop contributions primarily from top. Not to be confused with the <code>HiggsBSM:qg2H1q</code> process above, with its direct fermion-to-Higgs coupling. Code 1035. <p/><code>flag </code><strong> HiggsBSM:qqbar2H2g(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> H^0 g</i> via an <i>s</i>-channel gluon and loop contributions primarily from top. Is strictly speaking a "new" process, not directly derived from <i>g g -> H^0</i>, and could therefore be included in the standard mix without double-counting, but is numerically negligible. Code 1036. <h4>3) <i>A^0(H_3^0)</i> processes</h4> <p/><code>flag </code><strong> HiggsBSM:qg2A3q </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q g -> A^0 q</i>. This process gives first-order corrections to the <i>f fbar -> A^0</i> one above, and should only be used to study the high-<i>pT</i> tail, while <i>f fbar -> A^0</i> should be used for inclusive production. Only the dominant <i>c</i> and <i>b</i> contributions are included, and generated separately for technical reasons. Note that another first-order process would be <i>q qbar -> A^0 g</i>, which is not explicitly implemented here, but is obtained from showering off the lowest-order process. It does not contain any <i>b</i> at large <i>pT</i>, however, so is less interesting for many applications. Code 1051. <p/><code>flag </code><strong> HiggsBSM:gg2A3bbbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> A^0 b bbar</i>. This process is yet one order higher of the <i>b bbar -> A^0</i> and <i>b g -> A^0 b</i> chain, where now two quarks should be required above some large <i>pT</i> threshold. Warning: unfortunately this process is rather slow, owing to a lengthy cross-section expression and inefficient phase-space selection. Code 1052. <p/><code>flag </code><strong> HiggsBSM:qqbar2A3bbbar </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> A^0 b bbar</i> via an <i>s</i>-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. <p/><code>flag </code><strong> HiggsBSM:gg2A3g(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>g g -> A^0 g</i> via loop contributions primarily from top. Code 1054. <p/><code>flag </code><strong> HiggsBSM:qg2A3q(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q g -> A^0 q</i> via loop contributions primarily from top. Not to be confused with the <code>HiggsBSM:qg2H1q</code> process above, with its direct fermion-to-Higgs coupling. Code 1055. <p/><code>flag </code><strong> HiggsBSM:qqbar2A3g(l:t) </strong> (<code>default = <strong>off</strong></code>)<br/> Scattering <i>q qbar -> A^0 g</i> via an <i>s</i>-channel gluon and loop contributions primarily from top. Is strictly speaking a "new" process, not directly derived from <i>g g -> A^0</i>, and could therefore be included in the standard mix without double-counting, but is numerically negligible. Code 1056. <h3>Parameters for Beyond-the-Standard-Model Higgs production and decay</h3> 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 <a href="SUSYLesHouchesAccord.html" target="page">SUSY Les Houches Accord</a>, 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. <p/> Masses would be set in the <code>ParticleData</code> 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 <i>A^0 -> H^0 Z^0</i> obviously is also valid for <i>H^0 -> A^0 Z^0</i> and <i>Z^0 -> H^0 A^0</i>. Note that couplings usually appear quadratically in matrix elements. <p/><code>parm </code><strong> HiggsH1:coup2d </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>h^0(H_1^0)</i> coupling to down-type quarks. <p/><code>parm </code><strong> HiggsH1:coup2u </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>h^0(H_1^0)</i> coupling to up-type quarks. <p/><code>parm </code><strong> HiggsH1:coup2l </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>h^0(H_1^0)</i> coupling to (charged) leptons. <p/><code>parm </code><strong> HiggsH1:coup2Z </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>h^0(H_1^0)</i> coupling to <i>Z^0</i>. <p/><code>parm </code><strong> HiggsH1:coup2W </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>h^0(H_1^0)</i> coupling to <i>W^+-</i>. <p/><code>parm </code><strong> HiggsH1:coup2Hchg </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>h^0(H_1^0)</i> coupling to <i>H^+-</i> (in loops). Is <i>sin(beta - alpha) + cos(2 beta) sin(beta + alpha) / (2 cos^2theta_W)</i> in the MSSM. <p/><code>parm </code><strong> HiggsH2:coup2d </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to down-type quarks. <p/><code>parm </code><strong> HiggsH2:coup2u </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to up-type quarks. <p/><code>parm </code><strong> HiggsH2:coup2l </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to (charged) leptons. <p/><code>parm </code><strong> HiggsH2:coup2Z </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to <i>Z^0</i>. <p/><code>parm </code><strong> HiggsH2:coup2W </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to <i>W^+-</i>. <p/><code>parm </code><strong> HiggsH2:coup2Hchg </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to <i>H^+-</i> (in loops). Is <i>cos(beta - alpha) + cos(2 beta) cos(beta + alpha) / (2 cos^2theta_W)</i> in the MSSM. <p/><code>parm </code><strong> HiggsH2:coup2H1H1 </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to a <i>h^0(H_1^0)</i> pair. Is <i>cos(2 alpha) cos(beta + alpha) - 2 sin(2 alpha) sin(beta + alpha)</i> in the MSSM. <p/><code>parm </code><strong> HiggsH2:coup2A3A3 </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to an <i>A^0(H_3^0)</i> pair. Is <i>cos(2 beta) cos(beta + alpha)</i> in the MSSM. <p/><code>parm </code><strong> HiggsH2:coup2H1Z </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to a <i>h^0(H_1^0) Z^0</i> pair. Vanishes in the MSSM. <p/><code>parm </code><strong> HiggsH2:coup2A3H1 </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to an <i>A^0(H_3^0) h^0(H_1^0)</i> pair. Vanishes in the MSSM. <p/><code>parm </code><strong> HiggsH2:coup2HchgW </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>H^0(H_2^0)</i> coupling to a <i>H^+- W-+</i> pair. Is <i>sin(beta - alpha)</i> in the MSSM. <p/><code>parm </code><strong> HiggsA3:coup2d </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to down-type quarks. <p/><code>parm </code><strong> HiggsA3:coup2u </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to up-type quarks. <p/><code>parm </code><strong> HiggsA3:coup2l </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to (charged) leptons. <p/><code>parm </code><strong> HiggsA3:coup2H1Z </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to a <i>h^0(H_1^0) Z^0</i> pair. Is <i>cos(beta - alpha)</i> in the MSSM. <p/><code>parm </code><strong> HiggsA3:coup2H2Z </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to a <i>H^0(H_2^0) Z^0</i> pair. Is <i>sin(beta - alpha)</i> in the MSSM. <p/><code>parm </code><strong> HiggsA3:coup2Z </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to <i>Z^0</i>. Vanishes in the MSSM. <p/><code>parm </code><strong> HiggsA3:coup2W </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to <i>W^+-</i>. Vanishes in the MSSM. <p/><code>parm </code><strong> HiggsA3:coup2H1H1 </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to a <i>h^0(H_1^0)</i> pair. Vanishes in the MSSM. <p/><code>parm </code><strong> HiggsA3:coup2Hchg </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to <i>H^+-</i>. Vanishes in the MSSM. <p/><code>parm </code><strong> HiggsA3:coup2HchgW </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>A^0(H_3^0)</i> coupling to a <i>H^+- W-+</i> pair. Is 1 in the MSSM. <p/><code>parm </code><strong> HiggsHchg:tanBeta </strong> (<code>default = <strong>5.</strong></code>)<br/> The <i>tan(beta)</i> value, which leads to an enhancement of the <i>H^+-</i> 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. <p/><code>parm </code><strong> HiggsHchg:coup2H1W </strong> (<code>default = <strong>1.</strong></code>)<br/> The <i>H^+-</i> coupling to a <i>h^0(H_1^0) W^+-</i> pair. Is <i>cos(beta - alpha)</i> in the MSSM. <p/><code>parm </code><strong> HiggsHchg:coup2H2W </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>H^+-</i> coupling to a <i>H^0(H_2^0) W^+-</i> pair. Is <i>sin(beta - alpha)</i> in the MSSM. <p/> Another set of parameters are not used in the production stage but exclusively for the description of angular distributions in decays. <p/><code>mode </code><strong> HiggsH1:parity </strong> (<code>default = <strong>1</strong></code>; <code>minimum = 0</code>; <code>maximum = 3</code>)<br/> possibility to modify angular decay correlations in the decay of a <i>h^0(H_1)</i> decay <i>Z^0 Z^0</i> or <i>W^+ W^-</i> to four fermions. Currently it does not affect the partial width of the channels, which is only based on the above parameters. <br/><code>option </code><strong> 0</strong> : isotropic decays. <br/><code>option </code><strong> 1</strong> : assuming the <i>h^0(H_1)</i> is a pure scalar (CP-even), as in the MSSM. <br/><code>option </code><strong> 2</strong> : assuming the <i>h^0(H_1)</i> is a pure pseudoscalar (CP-odd). <br/><code>option </code><strong> 3</strong> : assuming the <i>h^0(H_1)</i> is a mixture of the two, including the CP-violating interference term. The parameter <i>eta</i>, see below, sets the strength of the CP-odd admixture, with the interference term being proportional to <i>eta</i> and the CP-odd one to <i>eta^2</i>. <p/><code>parm </code><strong> HiggsH1:etaParity </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>eta</i> value of CP-violation in the <code>HiggsSM:parity = 3</code> option. <p/><code>mode </code><strong> HiggsH2:parity </strong> (<code>default = <strong>1</strong></code>; <code>minimum = 0</code>; <code>maximum = 3</code>)<br/> possibility to modify angular decay correlations in the decay of a <i>H^0(H_2)</i> decay <i>Z^0 Z^0</i> or <i>W^+ W^-</i> to four fermions. Currently it does not affect the partial width of the channels, which is only based on the above parameters. <br/><code>option </code><strong> 0</strong> : isotropic decays. <br/><code>option </code><strong> 1</strong> : assuming the <i>H^0(H_2)</i> is a pure scalar (CP-even), as in the MSSM. <br/><code>option </code><strong> 2</strong> : assuming the <i>H^0(H_2)</i> is a pure pseudoscalar (CP-odd). <br/><code>option </code><strong> 3</strong> : assuming the <i>H^0(H_2)</i> is a mixture of the two, including the CP-violating interference term. The parameter <i>eta</i>, see below, sets the strength of the CP-odd admixture, with the interference term being proportional to <i>eta</i> and the CP-odd one to <i>eta^2</i>. <p/><code>parm </code><strong> HiggsH2:etaParity </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>eta</i> value of CP-violation in the <code>HiggsSM:parity = 3</code> option. <p/><code>mode </code><strong> HiggsA3:parity </strong> (<code>default = <strong>2</strong></code>; <code>minimum = 0</code>; <code>maximum = 3</code>)<br/> possibility to modify angular decay correlations in the decay of a <i>A^0(H_3)</i> decay <i>Z^0 Z^0</i> or <i>W^+ W^-</i> to four fermions. Currently it does not affect the partial width of the channels, which is only based on the above parameters. <br/><code>option </code><strong> 0</strong> : isotropic decays. <br/><code>option </code><strong> 1</strong> : assuming the <i>A^0(H_3)</i> is a pure scalar (CP-even). <br/><code>option </code><strong> 2</strong> : assuming the <i>A^0(H_3)</i> is a pure pseudoscalar (CP-odd), as in the MSSM. <br/><code>option </code><strong> 3</strong> : assuming the <i>A^0(H_3)</i> is a mixture of the two, including the CP-violating interference term. The parameter <i>eta</i>, see below, sets the strength of the CP-odd admixture, with the interference term being proportional to <i>eta</i> and the CP-odd one to <i>eta^2</i>. <p/><code>parm </code><strong> HiggsA3:etaParity </strong> (<code>default = <strong>0.</strong></code>)<br/> The <i>eta</i> value of CP-violation in the <code>HiggsSM:parity = 3</code> option. </body> </html> <!-- Copyright (C) 2013 Torbjorn Sjostrand -->
