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[u/mrichter/AliRoot.git] / PYTHIA8 / pythia8130 / xmldoc / HiggsProcesses.xml
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5ad4eb21 1<chapter name="Higgs Processes">
2
3<h2>Higgs Processes</h2>
4
5This page documents Higgs production within and beyond the Standard Model
6(SM and BSM for short). This includes several different processes and,
7for the BSM scenarios, a large set of parameters that would only be fixed
8within a more specific framework such as MSSM. Two choices can be made
9irrespective of the particular model:
10
11<flag name="Higgs:cubicWidth" default="off">
12The partial width of a Higgs particle to a pair of gauge bosons,
13<ei>W^+ W^-</ei> or <ei>Z^0 Z^0</ei>, depends cubically on the
14Higgs mass. When selecting the Higgs according to a Breit-Wigner,
15so that the actual mass <ei>mHat</ei> does not agree with the
16nominal <ei>m_Higgs</ei> one, an ambiguity arises which of the
17two to use <ref>Sey95</ref>. The default is to use a linear
18dependence on <ei>mHat</ei>, i.e. a width proportional to
19<ei>m_Higgs^2 * mHat</ei>, while <code>on</code> gives a
20<ei>mHat^3</ei> dependence. This does not affect the widths to
21fermions, which only depend linearly on <ei>mHat</ei>.
22This flag is used both for SM and BSM Higgses.
23</flag>
24
25<flag name="Higgs:runningLoopMass" default="on">
26The partial width of a Higgs particle to a pair of gluons or photons,
27or a <ei>gamma Z^0</ei> pair, proceeds in part through quark loops,
28mainly <ei>b</ei> and <ei>t</ei>. There is some ambiguity what kind
29of masses to use. Default is running MSbar ones, but alternatively
30fixed pole masses are allowed (as was standard in PYTHIA 6), which
31typically gives a noticeably higher cross section for these channels.
32(For a decay to a pair of fermions, such as top, the running mass is
33used for couplings and the fixed one for phase space.)
34</flag>
35
36<h3>Standard-Model Higgs, basic processes</h3>
37
38This section provides the standard set of processes that can be
39run together to provide a reasonably complete overview of possible
40production channels for a single SM Higgs.
41The main parameter is the choice of Higgs mass, which can be set in the
42normal <code>ParticleDataTable</code> database; thereafter the properties
43within the SM are essentially fixed.
44
45<flag name="HiggsSM:all" default="off">
46Common switch for the group of Higgs production within the Standard Model.
47</flag>
48
49<flag name="HiggsSM:ffbar2H" default="off">
50Scattering <ei>f fbar -> H^0</ei>, where <ei>f</ei> sums over available
51flavours except top. Related to the mass-dependent Higgs point coupling
52to fermions, so at hadron colliders the bottom contribution will
53dominate.
54Code 901.
55</flag>
56
57<flag name="HiggsSM:gg2H" default="off">
58Scattering <ei>g g -> H^0</ei> via loop contributions primarily from
59top.
60Code 902.
61</flag>
62
63<flag name="HiggsSM:gmgm2H" default="off">
64Scattering <ei>gamma gamma -> H^0</ei> via loop contributions primarily
65from top and <ei>W</ei>.
66Code 903.
67</flag>
68
69<flag name="HiggsSM:ffbar2HZ" default="off">
70Scattering <ei>f fbar -> H^0 Z^0</ei> via <ei>s</ei>-channel <ei>Z^0</ei>
71exchange.
72Code 904.
73</flag>
74
75<flag name="HiggsSM:ffbar2HW" default="off">
76Scattering <ei>f fbar -> H^0 W^+-</ei> via <ei>s</ei>-channel <ei>W^+-</ei>
77exchange.
78Code 905.
79</flag>
80
81<flag name="HiggsSM:ff2Hff(t:ZZ)" default="off">
82Scattering <ei>f f' -> H^0 f f'</ei> via <ei>Z^0 Z^0</ei> fusion.
83Code 906.
84</flag>
85
86<flag name="HiggsSM:ff2Hff(t:WW)" default="off">
87Scattering <ei>f_1 f_2 -> H^0 f_3 f_4</ei> via <ei>W^+ W^-</ei> fusion.
88Code 907.
89</flag>
90
91<flag name="HiggsSM:gg2Httbar" default="off">
92Scattering <ei>g g -> H^0 t tbar</ei> via <ei>t tbar</ei> fusion
93(or, alternatively put, Higgs radiation off a top line).
94Warning: unfortunately this process is rather slow, owing to a
95lengthy cross-section expression and inefficient phase-space selection.
96Code 908.
97</flag>
98
99<flag name="HiggsSM:qqbar2Httbar" default="off">
100Scattering <ei>q qbar -> H^0 t tbar</ei> via <ei>t tbar</ei> fusion
101(or, alternatively put, Higgs radiation off a top line).
102Warning: unfortunately this process is rather slow, owing to a
103lengthy cross-section expression and inefficient phase-space selection.
104Code 909.
105</flag>
106
107<h3>Standard-Model Higgs, further processes</h3>
108
109A number of further production processes has been implemented, that
110are specializations of some of the above ones to the high-<ei>pT</ei>
111region. The sets therefore could not be used simultaneously
112without unphysical doublecounting, as further explained below.
113They are not switched on by the <code>HiggsSM:all</code> flag, but
114have to be switched on for each separate process after due consideration.
115
116<p/>
117The first three processes in this section are related to the Higgs
118point coupling to fermions, and so primarily are of interest for
119<ei>b</ei> quarks. It is here useful to begin by reminding that
120a process like <ei>b bbar -> H^0</ei> implies that a <ei>b/bbar</ei>
121is taken from each incoming hadron, leaving behind its respective
122antiparticle. The initial-state showers will then add one
123<ei>g -> b bbar</ei> branching on either side, so that effectively
124the process becomes <ei>g g -> H0 b bbar</ei>. This would be the
125same basic process as the <ei>g g -> H^0 t tbar</ei> one used for top.
126The difference is that (a) no PDF's are defined for top and
127(b) the shower approach would not be good enough to provide sensible
128kinematics for the <ei>H^0 t tbar</ei> subsystem. By contrast, owing
129to the <ei>b</ei> being much lighter than the Higgs, multiple
130gluon emissions must be resummed for <ei>b</ei>, as is done by PDF's
131and showers, in order to obtain a sensible description of the total
132production rate, when the <ei>b</ei> quarks predominantly are produced
133at small <ei>pT</ei> values.
134
135<flag name="HiggsSM:qg2Hq" default="off">
136Scattering <ei>q g -> H^0 q</ei>. This process gives first-order
137corrections to the <ei>f fbar -> H^0</ei> one above, and should only be
138used to study the high-<ei>pT</ei> tail, while <ei>f fbar -> H^0</ei>
139should be used for inclusive production. Only the dominant <ei>c</ei>
140and <ei>b</ei> contributions are included, and generated separately
141for technical reasons. Note that another first-order process would be
142<ei>q qbar -> H^0 g</ei>, which is not explicitly implemented here,
143but is obtained from showering off the lowest-order process. It does not
144contain any <ei>b</ei> at large <ei>pT</ei>, however, so is less
145interesting for many applications.
146Code 911.
147
148</flag>
149<flag name="HiggsSM:gg2Hbbbar" default="off">
150Scattering <ei>g g -> H^0 b bbar</ei>. This process is yet one order
151higher of the <ei>b bbar -> H^0</ei> and <ei>b g -> H^0 b</ei> chain,
152where now two quarks should be required above some large <ei>pT</ei>
153threshold.
154Warning: unfortunately this process is rather slow, owing to a
155lengthy cross-section expression and inefficient phase-space selection.
156Code 912.
157</flag>
158
159<flag name="HiggsSM:qqbar2Hbbbar" default="off">
160Scattering <ei>q qbar -> H^0 b bbar</ei> via an <ei>s</ei>-channel
161gluon, so closely related to the previous one, but typically less
162important owing to the smaller rate of (anti)quarks relative to
163gluons.
164Warning: unfortunately this process is rather slow, owing to a
165lengthy cross-section expression and inefficient phase-space selection.
166Code 913.
167</flag>
168
169<p/>
170The second set of processes are predominantly first-order corrections
171to the <ei>g g -> H^0</ei> process, again dominated by the top loop.
172We here only provide the kinematical expressions obtained in the
173limit that the top quark goes to infinity, but scaled to the
174finite-top-mass coupling in <ei>g g -> H^0</ei>. (Complete loop
175expressions are available e.g. in PYTHIA 6.4 but are very lengthy.)
176This provides a reasonably accurate description for "intermediate"
177<ei>pT</ei> values, but fails when the <ei>pT</ei> scale approaches
178the top mass.
179
180<flag name="HiggsSM:gg2Hg(l:t)" default="off">
181Scattering <ei>g g -> H^0 g</ei> via loop contributions primarily
182from top.
183Code 914.
184</flag>
185
186<flag name="HiggsSM:qg2Hq(l:t)" default="off">
187Scattering <ei>q g -> H^0 q</ei> via loop contributions primarily
188from top. Not to be confused with the <code>HiggsSM:bg2Hb</code>
189process above, with its direct fermion-to-Higgs coupling.
190Code 915.
191</flag>
192
193<flag name="HiggsSM:qqbar2Hg(l:t)" default="off">
194Scattering <ei>q qbar -> H^0 g</ei> via an <ei>s</ei>-channel gluon
195and loop contributions primarily from top. Is strictly speaking a
196"new" process, not directly derived from <ei>g g -> H^0</ei>, and
197could therefore be included in the standard mix without doublecounting,
198but is numerically negligible.
199Code 916.
200</flag>
201
202<h3>Beyond-the-Standard-Model Higgs, introduction</h3>
203
204Further Higgs multiplets arise in a number of scenarios. We here
205concentrate on the MSSM scenario with two Higgs doublets, but with
206flexibility enough that also other two-Higgs-doublet scenarios could
207be represented by a suitable choice of parameters. Conventionally the
208Higgs states are labelled <ei>h^0, H^0, A^0</ei> and <ei>H^+-</ei>.
209If the scalar and pseudocalar states mix the resulting states are
210labelled <ei>H_1^0, H_2^0, H_3^0</ei>. In process names and parameter
211explanations both notations will be used, but for settings labels
212we have adapted the shorthand hybrid notation <code>H1</code> for
213<ei>h^0(H_1^0)</ei>, <code>H2</code> for <ei>H^0(H_2^0)</ei> and
214<code>A3</code> for <ei>A^0(H_3^0)</ei>. (Recall that the
215<code>Settings</code> database does not distinguish upper- and lowercase
216characters, so that the user has one thing less to worry about, but here
217it causes probles with <ei>h^0</ei> vs. <ei>H^0</ei>.) We leave the issue
218of mass ordering between <ei>H^0</ei> and <ei>A^0</ei> open, and thereby
219also that of <ei>H_2^0</ei> and <ei>H_3^0</ei>.
220
221<flag name="Higgs:useBSM" default="off">
222Master switch to initialize and use the two-Higgs-doublet states.
223If off, only the above SM Higgs processes can be used, with couplings
224as predicted in the SM. If on, only the below BSM Higgs processes can
225be used, with couplings that can be set freely, also found further down
226on this page.
227</flag>
228
229<h3>Beyond-the-Standard-Model Higgs, basic processes</h3>
230
231This section provides the standard set of processes that can be
232run together to provide a reasonably complete overview of possible
233production channels for a single neutral Higgs state in a two-doublet
234scenarios such as MSSM. The list of processes for neutral states closely
235mimics the one found for the SM Higgs. Some of the processes
236vanish for a pure pseudoscalar <ei>A^0</ei>, but are kept for flexiblity
237in cases of mixing with the scalar <ei>h^0</ei> and <ei>H^0</ei> states,
238or for use in the context of non-MSSM models. This should work well to
239represent e.g. that a small admixture of the "wrong" parity would allow
240a process such as <ei>q qbar -> A^0 Z^0</ei>, which otherwise is forbidden.
241However, note that the loop integrals e.g. for <ei>g g -> h^0/H^0/A^0</ei>
242are hardcoded to be for scalars for the former two particles and for a
243pseudoscalar for the latter one, so absolute rates would not be
244correctly represented in the case of large scalar/pseudoscalar mixing.
245
246<flag name="HiggsBSM:all" default="off">
247Common switch for the group of Higgs production beyond the Standard Model,
248as listed below.
249</flag>
250
251<h4>1) <ei>h^0(H_1^0)</ei> processes</h4>
252
253<flag name="HiggsBSM:allH1" default="off">
254Common switch for the group of <ei>h^0(H_1^0)</ei> production processes.
255</flag>
256
257<flag name="HiggsBSM:ffbar2H1" default="off">
258Scattering <ei>f fbar -> h^0(H_1^0)</ei>, where <ei>f</ei> sums over available
259flavours except top.
260Code 1001.
261</flag>
262
263<flag name="HiggsBSM:gg2H1" default="off">
264Scattering <ei>g g -> h^0(H_1^0)</ei> via loop contributions primarily from
265top.
266Code 1002.
267</flag>
268
269<flag name="HiggsBSM:gmgm2H1" default="off">
270Scattering <ei>gamma gamma -> h^0(H_1^0)</ei> via loop contributions primarily
271from top and <ei>W</ei>.
272Code 1003.
273</flag>
274
275<flag name="HiggsBSM:ffbar2H1Z" default="off">
276Scattering <ei>f fbar -> h^0(H_1^0) Z^0</ei> via <ei>s</ei>-channel <ei>Z^0</ei>
277exchange.
278Code 1004.
279</flag>
280
281<flag name="HiggsBSM:ffbar2H1W" default="off">
282Scattering <ei>f fbar -> h^0(H_1^0) W^+-</ei> via <ei>s</ei>-channel <ei>W^+-</ei>
283exchange.
284Code 1005.
285</flag>
286
287<flag name="HiggsBSM:ff2H1ff(t:ZZ)" default="off">
288Scattering <ei>f f' -> h^0(H_1^0) f f'</ei> via <ei>Z^0 Z^0</ei> fusion.
289Code 1006.
290</flag>
291
292<flag name="HiggsBSM:ff2H1ff(t:WW)" default="off">
293Scattering <ei>f_1 f_2 -> h^0(H_1^0) f_3 f_4</ei> via <ei>W^+ W^-</ei> fusion.
294Code 1007.
295</flag>
296
297<flag name="HiggsBSM:gg2H1ttbar" default="off">
298Scattering <ei>g g -> h^0(H_1^0) t tbar</ei> via <ei>t tbar</ei> fusion
299(or, alternatively put, Higgs radiation off a top line).
300Warning: unfortunately this process is rather slow, owing to a
301lengthy cross-section expression and inefficient phase-space selection.
302Code 1008.
303</flag>
304
305<flag name="HiggsBSM:qqbar2H1ttbar" default="off">
306Scattering <ei>q qbar -> h^0(H_1^0) t tbar</ei> via <ei>t tbar</ei> fusion
307(or, alternatively put, Higgs radiation off a top line).
308Warning: unfortunately this process is rather slow, owing to a
309lengthy cross-section expression and inefficient phase-space selection.
310Code 1009.
311
312
313<h4>2) <ei>H^0(H_2^0)</ei> processes</h4>
314
315<flag name="HiggsBSM:allH2" default="off">
316Common switch for the group of <ei>H^0(H_2^0)</ei> production processes.
317</flag>
318
319<flag name="HiggsBSM:ffbar2H2" default="off">
320Scattering <ei>f fbar -> H^0(H_2^0)</ei>, where <ei>f</ei> sums over available
321flavours except top.
322Code 1021.
323</flag>
324
325<flag name="HiggsBSM:gg2H2" default="off">
326Scattering <ei>g g -> H^0(H_2^0)</ei> via loop contributions primarily from
327top.
328Code 1022.
329</flag>
330
331<flag name="HiggsBSM:gmgm2H2" default="off">
332Scattering <ei>gamma gamma -> H^0(H_2^0)</ei> via loop contributions primarily
333from top and <ei>W</ei>.
334Code 1023.
335</flag>
336
337<flag name="HiggsBSM:ffbar2H2Z" default="off">
338Scattering <ei>f fbar -> H^0(H_2^0) Z^0</ei> via <ei>s</ei>-channel <ei>Z^0</ei>
339exchange.
340Code 1024.
341</flag>
342
343<flag name="HiggsBSM:ffbar2H2W" default="off">
344Scattering <ei>f fbar -> H^0(H_2^0) W^+-</ei> via <ei>s</ei>-channel <ei>W^+-</ei>
345exchange.
346Code 1025.
347</flag>
348
349<flag name="HiggsBSM:ff2H2ff(t:ZZ)" default="off">
350Scattering <ei>f f' -> H^0(H_2^0) f f'</ei> via <ei>Z^0 Z^0</ei> fusion.
351Code 1026.
352</flag>
353
354<flag name="HiggsBSM:ff2H2ff(t:WW)" default="off">
355Scattering <ei>f_1 f_2 -> H^0(H_2^0) f_3 f_4</ei> via <ei>W^+ W^-</ei> fusion.
356Code 1027.
357</flag>
358
359<flag name="HiggsBSM:gg2H2ttbar" default="off">
360Scattering <ei>g g -> H^0(H_2^0) t tbar</ei> via <ei>t tbar</ei> fusion
361(or, alternatively put, Higgs radiation off a top line).
362Warning: unfortunately this process is rather slow, owing to a
363lengthy cross-section expression and inefficient phase-space selection.
364Code 1028.
365</flag>
366
367<flag name="HiggsBSM:qqbar2H2ttbar" default="off">
368Scattering <ei>q qbar -> H^0(H_2^0) t tbar</ei> via <ei>t tbar</ei> fusion
369(or, alternatively put, Higgs radiation off a top line).
370Warning: unfortunately this process is rather slow, owing to a
371lengthy cross-section expression and inefficient phase-space selection.
372Code 1029.
373
374<h4>3) <ei>A^0(H_3^0)</ei> processes</h4>
375
376<flag name="HiggsBSM:allA3" default="off">
377Common switch for the group of <ei>A^0(H_3^0)</ei> production processes.
378</flag>
379
380<flag name="HiggsBSM:ffbar2A3" default="off">
381Scattering <ei>f fbar -> A^0(H_3^0)</ei>, where <ei>f</ei> sums over available
382flavours except top.
383Code 1041.
384</flag>
385
386<flag name="HiggsBSM:gg2A3" default="off">
387Scattering <ei>g g -> A^0(A_3^0)</ei> via loop contributions primarily from
388top.
389Code 1042.
390</flag>
391
392<flag name="HiggsBSM:gmgm2A3" default="off">
393Scattering <ei>gamma gamma -> A^0(A_3^0)</ei> via loop contributions primarily
394from top and <ei>W</ei>.
395Code 1043.
396</flag>
397
398<flag name="HiggsBSM:ffbar2A3Z" default="off">
399Scattering <ei>f fbar -> A^0(A_3^0) Z^0</ei> via <ei>s</ei>-channel <ei>Z^0</ei>
400exchange.
401Code 1044.
402</flag>
403
404<flag name="HiggsBSM:ffbar2A3W" default="off">
405Scattering <ei>f fbar -> A^0(A_3^0) W^+-</ei> via <ei>s</ei>-channel <ei>W^+-</ei>
406exchange.
407Code 1045.
408</flag>
409
410<flag name="HiggsBSM:ff2A3ff(t:ZZ)" default="off">
411Scattering <ei>f f' -> A^0(A_3^0) f f'</ei> via <ei>Z^0 Z^0</ei> fusion.
412Code 1046.
413</flag>
414
415<flag name="HiggsBSM:ff2A3ff(t:WW)" default="off">
416Scattering <ei>f_1 f_2 -> A^0(A_3^0) f_3 f_4</ei> via <ei>W^+ W^-</ei> fusion.
417Code 1047.
418</flag>
419
420<flag name="HiggsBSM:gg2A3ttbar" default="off">
421Scattering <ei>g g -> A^0(A_3^0) t tbar</ei> via <ei>t tbar</ei> fusion
422(or, alternatively put, Higgs radiation off a top line).
423Warning: unfortunately this process is rather slow, owing to a
424lengthy cross-section expression and inefficient phase-space selection.
425Code 1048.
426</flag>
427
428<flag name="HiggsBSM:qqbar2A3ttbar" default="off">
429Scattering <ei>q qbar -> A^0(A_3^0) t tbar</ei> via <ei>t tbar</ei> fusion
430(or, alternatively put, Higgs radiation off a top line).
431Warning: unfortunately this process is rather slow, owing to a
432lengthy cross-section expression and inefficient phase-space selection.
433Code 1049.
434
435<h4>4) <ei>H+-</ei> processes</h4>
436
437<flag name="HiggsBSM:allH+-" default="off">
438Common switch for the group of <ei>H^+-</ei> production processes.
439</flag>
440
441<flag name="HiggsBSM:ffbar2H+-" default="off">
442Scattering <ei>f fbar' -> H^+-</ei>, where <ei>f, fbar'</ei> sums over
443available incoming flavours. Since couplings are assumed
444generation-diagonal, in practice this means <ei>c sbar -> H^+</ei>
445and <ei>s cbar -> H^-</ei>.
446Code 1061.
447</flag>
448
449<flag name="HiggsBSM:bg2H+-t" default="off">
450Scattering <ei>b g -> H^+ tbar</ei>. At hadron colliders this is the
451dominant process for single-charged-Higgs production.
452Code 1062.
453</flag>
454
455<h4>5) Higgs-pair processes</h4>
456
457<flag name="HiggsBSM:allHpair" default="off">
458Common switch for the group of Higgs pair-production processes.
459</flag>
460
461<flag name="HiggsBSM:ffbar2A3H1" default="off">
462Scattering <ei>f fbar -> A^0(H_3) h^0(H_1)</ei>.
463Code 1081.
464</flag>
465
466<flag name="HiggsBSM:ffbar2A3H2" default="off">
467Scattering <ei>f fbar -> A^0(H_3) H^0(H_2)</ei>.
468Code 1082.
469</flag>
470
471<flag name="HiggsBSM:ffbar2H+-H1" default="off">
472Scattering <ei>f fbar -> H^+- h^0(H_1)</ei>.
473Code 1083.
474</flag>
475
476<flag name="HiggsBSM:ffbar2H+-H2" default="off">
477Scattering <ei>f fbar -> H^+- H^0(H_2)</ei>.
478Code 1084.
479</flag>
480
481<flag name="HiggsBSM:ffbar2H+H-" default="off">
482Scattering <ei>f fbar -> H+ H-</ei>.
483Code 1085.
484</flag>
485
486<h3>Beyond-the-Standard-Model Higgs, further processes</h3>
487
488This section mimics the above section on "Standard-Model Higgs,
489further processes", i.e. it contains higher-order corrections
490to the processes already listed. The two sets therefore could not
491be used simultaneously without unphysical doublecounting.
492They are not controlled by any group flag, but have to be switched
493on for each separate process after due consideration. We refer to
494the standard-model description for a set of further comments on
495the processes.
496
497<h4>1) <ei>h^0(H_1^0)</ei> processes</h4>
498
499<flag name="HiggsBSM:qg2H1q" default="off">
500Scattering <ei>q g -> h^0 q</ei>. This process gives first-order
501corrections to the <ei>f fbar -> h^0</ei> one above, and should only be
502used to study the high-<ei>pT</ei> tail, while <ei>f fbar -> h^0</ei>
503should be used for inclusive production. Only the dominant <ei>c</ei>
504and <ei>b</ei> contributions are included, and generated separately
505for technical reasons. Note that another first-order process would be
506<ei>q qbar -> h^0 g</ei>, which is not explicitly implemented here,
507but is obtained from showering off the lowest-order process. It does not
508contain any <ei>b</ei> at large <ei>pT</ei>, however, so is less
509interesting for many applications.
510Code 1011.
511</flag>
512
513<flag name="HiggsBSM:gg2H1bbbar" default="off">
514Scattering <ei>g g -> h^0 b bbar</ei>. This process is yet one order
515higher of the <ei>b bbar -> h^0</ei> and <ei>b g -> h^0 b</ei> chain,
516where now two quarks should be required above some large <ei>pT</ei>
517threshold.
518Warning: unfortunately this process is rather slow, owing to a
519lengthy cross-section expression and inefficient phase-space selection.
520Code 1012.
521</flag>
522
523<flag name="HiggsBSM:qqbar2H1bbbar" default="off">
524Scattering <ei>q qbar -> h^0 b bbar</ei> via an <ei>s</ei>-channel
525gluon, so closely related to the previous one, but typically less
526important owing to the smaller rate of (anti)quarks relative to
527gluons.
528Warning: unfortunately this process is rather slow, owing to a
529lengthy cross-section expression and inefficient phase-space selection.
530Code 1013.
531</flag>
532
533<flag name="HiggsBSM:gg2H1g(l:t)" default="off">
534Scattering <ei>g g -> h^0 g</ei> via loop contributions primarily
535from top.
536Code 1014.
537</flag>
538
539<flag name="HiggsBSM:qg2H1q(l:t)" default="off">
540Scattering <ei>q g -> h^0 q</ei> via loop contributions primarily
541from top. Not to be confused with the <code>HiggsBSM:bg2H1b</code>
542process above, with its direct fermion-to-Higgs coupling.
543Code 1015.
544</flag>
545
546<flag name="HiggsBSM:qqbar2H1g(l:t)" default="off">
547Scattering <ei>q qbar -> h^0 g</ei> via an <ei>s</ei>-channel gluon
548and loop contributions primarily from top. Is strictly speaking a
549"new" process, not directly derived from <ei>g g -> h^0</ei>, and
550could therefore be included in the standard mix without doublecounting,
551but is numerically negligible.
552Code 1016.
553</flag>
554
555<h4>2) <ei>H^0(H_2^0)</ei> processes</h4>
556
557<flag name="HiggsBSM:qg2H2q" default="off">
558Scattering <ei>q g -> H^0 q</ei>. This process gives first-order
559corrections to the <ei>f fbar -> H^0</ei> one above, and should only be
560used to study the high-<ei>pT</ei> tail, while <ei>f fbar -> H^0</ei>
561should be used for inclusive production. Only the dominant <ei>c</ei>
562and <ei>b</ei> contributions are included, and generated separately
563for technical reasons. Note that another first-order process would be
564<ei>q qbar -> H^0 g</ei>, which is not explicitly implemented here,
565but is obtained from showering off the lowest-order process. It does not
566contain any <ei>b</ei> at large <ei>pT</ei>, however, so is less
567interesting for many applications.
568Code 1031.
569</flag>
570
571<flag name="HiggsBSM:gg2H2bbbar" default="off">
572Scattering <ei>g g -> H^0 b bbar</ei>. This process is yet one order
573higher of the <ei>b bbar -> H^0</ei> and <ei>b g -> H^0 b</ei> chain,
574where now two quarks should be required above some large <ei>pT</ei>
575threshold.
576Warning: unfortunately this process is rather slow, owing to a
577lengthy cross-section expression and inefficient phase-space selection.
578Code 1032.
579</flag>
580
581<flag name="HiggsBSM:qqbar2H2bbbar" default="off">
582Scattering <ei>q qbar -> H^0 b bbar</ei> via an <ei>s</ei>-channel
583gluon, so closely related to the previous one, but typically less
584important owing to the smaller rate of (anti)quarks relative to
585gluons.
586Warning: unfortunately this process is rather slow, owing to a
587lengthy cross-section expression and inefficient phase-space selection.
588Code 1033.
589</flag>
590
591<flag name="HiggsBSM:gg2H2g(l:t)" default="off">
592Scattering <ei>g g -> H^0 g</ei> via loop contributions primarily
593from top.
594Code 1034.
595</flag>
596
597<flag name="HiggsBSM:qg2H2q(l:t)" default="off">
598Scattering <ei>q g -> H^0 q</ei> via loop contributions primarily
599from top. Not to be confused with the <code>HiggsBSM:bg2H1b</code>
600process above, with its direct fermion-to-Higgs coupling.
601Code 1035.
602</flag>
603
604<flag name="HiggsBSM:qqbar2H2g(l:t)" default="off">
605Scattering <ei>q qbar -> H^0 g</ei> via an <ei>s</ei>-channel gluon
606and loop contributions primarily from top. Is strictly speaking a
607"new" process, not directly derived from <ei>g g -> H^0</ei>, and
608could therefore be included in the standard mix without doublecounting,
609but is numerically negligible.
610Code 1036.
611</flag>
612
613<h4>3) <ei>A^0(H_3^0)</ei> processes</h4>
614
615<flag name="HiggsBSM:qg2A3q" default="off">
616Scattering <ei>q g -> A^0 q</ei>. This process gives first-order
617corrections to the <ei>f fbar -> A^0</ei> one above, and should only be
618used to study the high-<ei>pT</ei> tail, while <ei>f fbar -> A^0</ei>
619should be used for inclusive production. Only the dominant <ei>c</ei>
620and <ei>b</ei> contributions are included, and generated separately
621for technical reasons. Note that another first-order process would be
622<ei>q qbar -> A^0 g</ei>, which is not explicitly implemented here,
623but is obtained from showering off the lowest-order process. It does not
624contain any <ei>b</ei> at large <ei>pT</ei>, however, so is less
625interesting for many applications.
626Code 1051.
627</flag>
628
629<flag name="HiggsBSM:gg2A3bbbar" default="off">
630Scattering <ei>g g -> A^0 b bbar</ei>. This process is yet one order
631higher of the <ei>b bbar -> A^0</ei> and <ei>b g -> A^0 b</ei> chain,
632where now two quarks should be required above some large <ei>pT</ei>
633threshold.
634Warning: unfortunately this process is rather slow, owing to a
635lengthy cross-section expression and inefficient phase-space selection.
636Code 1052.
637</flag>
638
639<flag name="HiggsBSM:qqbar2A3bbbar" default="off">
640Scattering <ei>q qbar -> A^0 b bbar</ei> via an <ei>s</ei>-channel
641gluon, so closely related to the previous one, but typically less
642important owing to the smaller rate of (anti)quarks relative to
643gluons.
644Warning: unfortunately this process is rather slow, owing to a
645lengthy cross-section expression and inefficient phase-space selection.
646Code 1053.
647</flag>
648
649<flag name="HiggsBSM:gg2A3g(l:t)" default="off">
650Scattering <ei>g g -> A^0 g</ei> via loop contributions primarily
651from top.
652Code 1054.
653</flag>
654
655<flag name="HiggsBSM:qg2A3q(l:t)" default="off">
656Scattering <ei>q g -> A^0 q</ei> via loop contributions primarily
657from top. Not to be confused with the <code>HiggsBSM:bg2H1b</code>
658process above, with its direct fermion-to-Higgs coupling.
659Code 1055.
660</flag>
661
662<flag name="HiggsBSM:qqbar2A3g(l:t)" default="off">
663Scattering <ei>q qbar -> A^0 g</ei> via an <ei>s</ei>-channel gluon
664and loop contributions primarily from top. Is strictly speaking a
665"new" process, not directly derived from <ei>g g -> A^0</ei>, and
666could therefore be included in the standard mix without doublecounting,
667but is numerically negligible.
668Code 1056.
669</flag>
670
671<h3>Parameters for Beyond-the-Standard-Model Higgs production and decay</h3>
672
673This section offers a big flexibility to set couplings of the various
674Higgs states to fermions and gauge bosons, and also to each other.
675The intention is that, for scenarios like MSSM, you should use standard
676input from the <aloc href="SUSYLesHouchesAccord">SUSY Les Houches
677Accord</aloc>, rather than having to set it all yourself. In other cases,
678however, the freedom is there for you to use. Kindly note that some
679of the internal calculations of partial widths from the parameters provided
680do not include mixing between the scalar and pseudoscalar states.
681
682<p/>
683Masses would be set in the <code>ParticleDataTable</code> database,
684while couplings are set below. When possible, the couplings of the Higgs
685states are normalized to the corresponding coupling within the SM.
686When not, their values within the MSSM are indicated, from which
687it should be straightforward to understand what to use instead.
688The exception is some couplings that vanish also in the MSSM, where the
689normalization has been defined in close analogy with nonvanishing ones.
690Some parameter names are asymmetric but crossing can always be used,
691i.e. the coupling for <ei>A^0 -> H^0 Z^0</ei> obviously is also valid
692for <ei>H^0 -> A^0 Z^0</ei> and <ei>Z^0 -> H^0 A^0</ei>.
693Note that couplings usually appear quadratically in matrix elements.
694
695<parm name="HiggsH1:coup2d" default="1.">
696The <ei>h^0(H_1^0)</ei> coupling to down-type quarks.
697</parm>
698
699<parm name="HiggsH1:coup2u" default="1.">
700The <ei>h^0(H_1^0)</ei> coupling to up-type quarks.
701</parm>
702
703<parm name="HiggsH1:coup2l" default="1.">
704The <ei>h^0(H_1^0)</ei> coupling to (charged) leptons.
705</parm>
706
707<parm name="HiggsH1:coup2Z" default="1.">
708The <ei>h^0(H_1^0)</ei> coupling to <ei>Z^0</ei>.
709</parm>
710
711<parm name="HiggsH1:coup2W" default="1.">
712The <ei>h^0(H_1^0)</ei> coupling to <ei>W^+-</ei>.
713</parm>
714
715<parm name="HiggsH1:coup2Hchg" default="0.">
716The <ei>h^0(H_1^0)</ei> coupling to <ei>H^+-</ei> (in loops).
717Is <ei>sin(beta - alpha) + cos(2 beta) sin(beta + alpha) /
718(2 cos^2theta_W)</ei> in the MSSM.
719</parm>
720
721<parm name="HiggsH2:coup2d" default="1.">
722The <ei>H^0(H_2^0)</ei> coupling to down-type quarks.
723</parm>
724
725<parm name="HiggsH2:coup2u" default="1.">
726The <ei>H^0(H_2^0)</ei> coupling to up-type quarks.
727</parm>
728
729<parm name="HiggsH2:coup2l" default="1.">
730The <ei>H^0(H_2^0)</ei> coupling to (charged) leptons.
731</parm>
732
733<parm name="HiggsH2:coup2Z" default="1.">
734The <ei>H^0(H_2^0)</ei> coupling to <ei>Z^0</ei>.
735</parm>
736
737<parm name="HiggsH2:coup2W" default="1.">
738The <ei>H^0(H_2^0)</ei> coupling to <ei>W^+-</ei>.
739</parm>
740
741<parm name="HiggsH2:coup2Hchg" default="0.">
742The <ei>H^0(H_2^0)</ei> coupling to <ei>H^+-</ei> (in loops).
743Is <ei>cos(beta - alpha) + cos(2 beta) cos(beta + alpha) /
744(2 cos^2theta_W)</ei> in the MSSM.
745</parm>
746
747<parm name="HiggsH2:coup2H1H1" default="1.">
748The <ei>H^0(H_2^0)</ei> coupling to a <ei>h^0(H_1^0)</ei> pair.
749Is <ei>cos(2 alpha) cos(beta + alpha) - 2 sin(2 alpha)
750sin(beta + alpha)</ei> in the MSSM.
751</parm>
752
753<parm name="HiggsH2:coup2A3A3" default="1.">
754The <ei>H^0(H_2^0)</ei> coupling to an <ei>A^0(H_3^0)</ei> pair.
755Is <ei>cos(2 beta) cos(beta + alpha)</ei> in the MSSM.
756</parm>
757
758<parm name="HiggsH2:coup2H1Z" default="0.">
759The <ei>H^0(H_2^0)</ei> coupling to a <ei>h^0(H_1^0) Z^0</ei> pair.
760Vanishes in the MSSM.
761</parm>
762
763<parm name="HiggsH2:coup2A3H1" default="0.">
764The <ei>H^0(H_2^0)</ei> coupling to an <ei>A^0(H_3^0) h^0(H_1^0)</ei> pair.
765Vanishes in the MSSM.
766</parm>
767
768<parm name="HiggsH2:coup2HchgW" default="0.">
769The <ei>H^0(H_2^0)</ei> coupling to a <ei>H^+- W-+</ei> pair.
770Vanishes in the MSSM.
771</parm>
772
773<parm name="HiggsA3:coup2d" default="1.">
774The <ei>A^0(H_3^0)</ei> coupling to down-type quarks.
775</parm>
776
777<parm name="HiggsA3:coup2u" default="1.">
778The <ei>A^0(H_3^0)</ei> coupling to up-type quarks.
779</parm>
780
781<parm name="HiggsA3:coup2l" default="1.">
782The <ei>A^0(H_3^0)</ei> coupling to (charged) leptons.
783</parm>
784
785<parm name="HiggsA3:coup2H1Z" default="1.">
786The <ei>A^0(H_3^0)</ei> coupling to a <ei>h^0(H_1^0) Z^0</ei> pair.
787Is <ei>cos(beta - alpha)</ei> in the MSSM.
788</parm>
789
790<parm name="HiggsA3:coup2H2Z" default="1.">
791The <ei>A^0(H_3^0)</ei> coupling to a <ei>H^0(H_2^0) Z^0</ei> pair.
792Is <ei>sin(beta - alpha)</ei> in the MSSM.
793</parm>
794
795<parm name="HiggsA3:coup2Z" default="0.">
796The <ei>A^0(H_3^0)</ei> coupling to <ei>Z^0</ei>.
797Vanishes in the MSSM.
798</parm>
799
800<parm name="HiggsA3:coup2W" default="0.">
801The <ei>A^0(H_3^0)</ei> coupling to <ei>W^+-</ei>.
802Vanishes in the MSSM.
803</parm>
804
805<parm name="HiggsA3:coup2H1H1" default="0.">
806The <ei>A^0(H_3^0)</ei> coupling to a <ei>h^0(H_1^0)</ei> pair.
807Vanishes in the MSSM.
808</parm>
809
810<parm name="HiggsA3:coup2Hchg" default="0.">
811The <ei>A^0(H_3^0)</ei> coupling to <ei>H^+-</ei>.
812Vanishes in the MSSM.
813</parm>
814
815<parm name="HiggsA3:coup2HchgW" default="0.">
816The <ei>A^0(H_3^0)</ei> coupling to a <ei>H^+- W-+</ei> pair.
817Vanishes in the MSSM.
818</parm>
819
820<parm name="HiggsHchg:tanBeta" default="5.">
821The <ei>tan(beta)</ei> value, which leads to an enhancement of the
822<ei>H^+-</ei> coupling to down-type fermions and suppression to
823up-type ones. The same angle also appears in many other places,
824but this particular parameter is only used for the charged-Higgs case.
825</parm>
826
827<parm name="HiggsHchg:coup2H1W" default="1.">
828The <ei>H^+-</ei> coupling to a <ei>h^0(H_1^0) W^+-</ei> pair.
829Is <ei>cos(beta - alpha)</ei> in the MSSM.
830</parm>
831
832<parm name="HiggsHchg:coup2H2W" default="0.">
833The <ei>H^+-</ei> coupling to a <ei>H^0(H_2^0) W^+-</ei> pair.
834Is <ei>1 - cos(beta - alpha)</ei> in the MSSM.
835</parm>
836
837<p/>
838Another set of parameters are not used in the production stage but
839exclusively for the description of angular distributions in decays.
840
841<modepick name="HiggsH1:parity" default="1" min="0" max="3">
842possibility to modify angular decay correlations in the decay of a
843<ei>h^0(H_1)</ei> decay <ei>Z^0 Z^0</ei> or <ei>W^+ W^-</ei> to four
844fermions. Currently it does not affect the partial width of the
845channels, which is only based on the above parameters.
846<option value="0">isotropic decays.</option>
847<option value="1">assuming the <ei>h^0(H_1)</ei> is a pure scalar
848(CP-even), as in the MSSM.</option>
849<option value="2">assuming the <ei>h^0(H_1)</ei> is a pure pseudoscalar
850(CP-odd).</option>
851<option value="3">assuming the <ei>h^0(H_1)</ei> is a mixture of the two,
852including the CP-violating interference term. The parameter
853<ei>eta</ei>, see below, sets the strength of the CP-odd admixture,
854with the interference term being proportional to <ei>eta</ei>
855and the CP-odd one to <ei>eta^2</ei>.</option>
856</modepick>
857
858<parm name="HiggsH1:etaParity" default="0.">
859The <ei>eta</ei> value of CP-violation in the
860<code>HiggsSM:parity = 3</code> option.
861</parm>
862
863<modepick name="HiggsH2:parity" default="1" min="0" max="3">
864possibility to modify angular decay correlations in the decay of a
865<ei>H^0(H_2)</ei> decay <ei>Z^0 Z^0</ei> or <ei>W^+ W^-</ei> to four
866fermions. Currently it does not affect the partial width of the
867channels, which is only based on the above parameters.
868<option value="0">isotropic decays.</option>
869<option value="1">assuming the <ei>H^0(H_2)</ei> is a pure scalar
870(CP-even), as in the MSSM.</option>
871<option value="2">assuming the <ei>H^0(H_2)</ei> is a pure pseudoscalar
872(CP-odd).</option>
873<option value="3">assuming the <ei>H^0(H_2)</ei> is a mixture of the two,
874including the CP-violating interference term. The parameter
875<ei>eta</ei>, see below, sets the strength of the CP-odd admixture,
876with the interference term being proportional to <ei>eta</ei>
877and the CP-odd one to <ei>eta^2</ei>.</option>
878</modepick>
879
880<parm name="HiggsH2:etaParity" default="0.">
881The <ei>eta</ei> value of CP-violation in the
882<code>HiggsSM:parity = 3</code> option.
883</parm>
884
885<modepick name="HiggsA3:parity" default="2" min="0" max="3">
886possibility to modify angular decay correlations in the decay of a
887<ei>A^0(H_3)</ei> decay <ei>Z^0 Z^0</ei> or <ei>W^+ W^-</ei> to four
888fermions. Currently it does not affect the partial width of the
889channels, which is only based on the above parameters.
890<option value="0">isotropic decays.</option>
891<option value="1">assuming the <ei>A^0(H_3)</ei> is a pure scalar
892(CP-even).</option>
893<option value="2">assuming the <ei>A^0(H_3)</ei> is a pure pseudoscalar
894(CP-odd), as in the MSSM.</option>
895<option value="3">assuming the <ei>A^0(H_3)</ei> is a mixture of the two,
896including the CP-violating interference term. The parameter
897<ei>eta</ei>, see below, sets the strength of the CP-odd admixture,
898with the interference term being proportional to <ei>eta</ei>
899and the CP-odd one to <ei>eta^2</ei>.</option>
900</modepick>
901
902<parm name="HiggsA3:etaParity" default="0.">
903The <ei>eta</ei> value of CP-violation in the
904<code>HiggsSM:parity = 3</code> option.
905</parm>
906
907</chapter>
908
909<!-- Copyright (C) 2008 Torbjorn Sjostrand -->
910