Changes between Version 1 and Version 2 of HAHM

Timestamp:

Nov 13, 2023, 3:33:13 PM (13 months ago)

Author:

DavidCurtin

Comment:

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HAHM

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+SM + Dark Vector + Dark Higgs Madgraph5 Model
+
+NOTE: FOR COMPILATION WITH FEYNRULES 2.3.31, USE v5 (see below)
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+A very simple extension of the standard model involves adding a "dark" U(1) gauge group that is broken by a dark higgs vev. The "dark vector" ZD can then kinetically mix with the U(1)B gauge boson, and the "dark higgs" S (or hS) can mix with the SM doublet higgs via the higgs portal |H|2|S|2 operator. (For a more complete definition see here.) This can induce a variety of exotic higgs decays like h → Z ZD (if kinetic mixing dominates) h → ZD ZD (if higgs mixing dominates) h → S S (if higgs mixing dominates)
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+S inherits its decay modes from the SM higgs, while ZD couples proportional to gauge charge, giving lepton-rich final states. Cascades like h → S S → ZDZDZDZD are also possible, giving 8 lepton final states.
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+This model has been studied in the literature, see e.g.Wells et al. 0801.3456, 0803.1243.
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+The Exotic Higgs Decays Working Group published a large survey (1312.4992) of possible exotic higgs decay modes, which also considers decays in the SM + Dark Vector + Dark Higgs model.
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+To facilitate experimental study of these interesting channels we have constructed a Madgraph5 model to implement this SM extension.
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+The model is constructed using FeynRules 2.0.23. It is originally based on the HAHM Model (https://feynrules.irmp.ucl.ac.be/wiki/HiddenAbelianHiggsModel), but has been extensively modified to correct typos and implement self-consistent derivation of all mixing angles from MZ, MZD, Mh, MhS mass eigenvalue inputs go beyond the small-mixing-approximation adopt a definition of mixing angles so that, for small higgs/kinetic mixing << 1, the corresponding mixing angles will also be << 1 regardless of whether the h/Z is heavier or lighter than hS/ZD, and self-consistently modify SM relations that result from Z-ZD mixing in two different ways (shift W-mass or Weinberg angle) It has also been combined with the Higgs Effective Theory Model (https://feynrules.irmp.ucl.ac.be/wiki/HiggsEffectiveTheory) to add the effective hgg and hγγ operators.
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+This MG model can also be used to generate NMSSM-type decays like h→SS→4b by setting kinetic mixing to be tiny (don't use exactly zero, it causes errors), and similarly to generate pure kinetic mixing phenomenology by setting the higgs mixing to zero.
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+This model has been verified to reproduce results obtained from analytical expressions for various decay widths.
+
+    HAHM_MG5model_v1: includes pdf manual with explicit usage instructions at the end)
+    HAHM_MG5model_v2: includes nonzero electron and muon yukawa couplings to simulate hs > mumu etc
+    HAHM_MG5model_v3: includes nonzero muon and yukawa MASSES to properly simulate zp > mumu etc at very low zd masses
+    HAHM_variableMW_v4_YUKseparate: includes Yukawa couplings for all generations of leptons
+    HAHM_MG5model_v5_allyuk: includes Yukawa couplings for ALL SM fermions, AND has been tweaked to compile with Feynrules 2.3.31
+
+If you have questions about the model please email David Curtin (david.r.curtin@gmail.com).
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+0th order tip: don't set any of the mixing angles to exactly zero. Use 10^-10 or something instead if you don't want that mixing.
+
+Branching Ratio Tables: In "Illuminating Dark Photons with High-Energy Colliders" (Curtin, Essig, Gori, Shelton, arXiv:1412.0018) we compute the dark photon total width and branching ratio to leptons Br(ZD->ll) including QCD corrections, using PDG experimental data for mZD < 12 GeV, and by repurposing the calculations of hep-ph/0005139 for mZD > 12 GeV. We also compute the exotic higgs decay branching ratios Br(h->ZdZ*->4l) and Br(h->ZdZd->4l).
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+All of these computed widths and branching ratios can be downloaded in the HiggsedDarkPhoton_BrTableData.txt file.
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+(See our paper for more details.)
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+References: If you use this MG model in your own theory study or experimental analysis, please cite the following references:
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+    "Exotic Decays of the 125 GeV Higgs Boson" by Curtin, Essig, Gori, Jaiswal, Katz, Liu, Liu, McKeen, Shelton, Strassler, Surujon, Tweedie and Zhong. (arXiv:1312.4992)
+    "Illuminating Dark Photons with High-Energy Colliders", by Curtin, Essig, Gori, Shelton (arXiv:1412.0018)