The Higgs Characterisation model

Authors

• LO
  • Priscila de Aquino & Kentarou Mawatari (Vrije Universiteit Brussel)
    • Emails: kentarou.mawatari @ vub.ac.be
• NLO
  • Federico Demartin (Universite Catholique de Louvain) & Marco Zaro (LPTHE, Paris)
    • Emails: federico.demartin @ uclouvain.be

Description of the model

This is a model file for the characterisation of the boson recently discovered at the LHC. Our effective lagrangian consists of the SM (except for the Higgs itself), expressed through the physical degrees of freedom present below the EWSB scale, plus a new bosonic state X(J^P) with spin/parity assignments J^P = 0⁺, 0^-, 1⁺, 1^-, or 2⁺. The new state can couple to SM particles via interactions of the lowest possible dimensions. In addition, the state 0⁺ is allowed to mix with the 0^- one, and can interact with SM particles with higher-dimensional operators beyond those of the SM. See more details in

• ​1306.6464 : P. Artoisenet, P. de Aquino, F. Demartin, R. Frederix, S. Frixione, F. Maltoni, M. K. Mandal, P. Mathews, K. Mawatari, V. Ravindran, S. Seth, P. Torrielli, M. Zaro, "A framework for Higgs characterisation" (JHEP11(2013)043).
• ​1307.5607 : P. de Aquino, K. Mawatari, "Characterising a Higgs-like resonance at the LHC" (Proceedings for HPNP2013).

Model files for LO

• HC.fr : the main model file.
• SM_HC.fr : This model requires the modified Standard Model implementation of FeynRules.
• Massless.rst, Cabibbo.rst : SM restriction files.
• HC.nb : this is an example Mathematica notebook that loads the model, calculates the Feynman rules and extract the model files within the UFO format.
• HC_UFO.zip : The model files in UFO format (for MadGraph5).

Model files for NLO (only for the J=0 case)

A few remarks before use; see the README file in the model.

• HC_NLO_X0_UFO.zip : The model files in UFO format (for MadGraph5).

You can find the explicit command lines of MG5_aMC in the following papers:

• ​1311.1829 : F. Maltoni, K. Mawatari, M. Zaro, "Higgs characterisation via vector-boson fusion and associated production: NLO and parton-shower effects" (EPJC74(2014)2710).
• ​1407.5089 : F. Demartin, F. Maltoni, K. Mawatari, B. Page, M. Zaro, "Higgs characterisation at NLO in QCD: CP properties of the top-quark Yukawa interaction" (EPJC74(2014)3065).
• ​1504.00611 : F. Demartin, F. Maltoni, K. Mawatari, M. Zaro, "Higgs production in association with a single top quark at the LHC" (EPJCxx(2015)xxxx).
• ​1505.07081 : F. Demartin, K. Mawatari, E. Vryonidou, M. Zaro, "Higgs characterisation: NLO and parton-shower effects" (Proceedings for HPNP2015).

The present model files contain parts of the following existing FR model files:

• 1) HEFT, author: C. Duhr
• 2) Minimal Zprime, author: L. Basso
• 3) RS, author: P. de Aquino
• 4) loop_sm, author: V. Hirschi

---

Version updates for LO

• 16.01.2013 - v1.0: release version.
• 04.04.2013 - v1.1: added the CP-odd Yukawa terms in the X0 lagrangian and modified the X2 HD lagrangian to be proportional to 1/Lambda^3.
• 15.04.2013 - v2.0: fixed a bug for the X2 lowest dimensional interactions with massive gauge bosons. Parametrization for X0 modified.
• 28.05.2013 - v2.1: fixed a bug for the X0 coupling to the massive vector bosons (SM couplings recovered).
• 27.06.2013 - v3.0: major update and version for the paper ​1306.6464.
• 04.07.2013 - v3.1: fixed a bug in the gluon/photon gauge fixing term for X2.
• 20.07.2013 - v3.2: put the X width = 0.00407 GeV by HXSWG; introduced kqa, kqb, kla, and klb, instead of kfa and kfb.
• 24.07.2013 - v3.3: added the SM X0 self-interactions and the effective g-g-X0-X0 intereaction.
• 17.10.2013 - v3.4: redefined 'kHdw' as a complex.
• 11.12.2013 - v4.0: based on FR2.0; fixed a sign of the AVV couplings; introduced kq3 for the X2 couplings to bottom and top.

Version updates for NLO

• 27.01.2014 - v1.0: release version.
• 03.04.2014 - v1.1: version compatible with MG5_aMCv2.1.1 or later.

---