The B-L model

as a U(1) extension of the SM with 3 RH neutrinos and a singlet scalar.

This is an update to the previous minimal Zprime model.

Implementation authors

• This version
  • Wei Liu
    • Department of Physics & Astronomy, University College London
    • wei.liu.16 -at- ucl.ac.uk
    • update based on Lorenzo Basso's model with availability to FeynRules 2.3 with the help of Dr. Frank Deppisch.

• Previous version
  • Lorenzo Basso
    • Physikalisches Institut, Albert-Ludwigs-Universität Freiburg (Germany)
    • lorenzo.basso -at- physik.uni-freiburg.de
    • (formerly at University of Southampton, UK & RAL-PPD, Didcot, UK)
    • Based upon the minimal B-L model implementation, done in collaboration with Giovanni Marco Pruna (TU Dresden, Institut für Kern- und Teilchenphysik, Dresden, Germany, formerly at University of Southampton, UK & RAL-PPD, Didcot, UK).

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Model description

The model describe a U(1) extension of the SM, related to the B-L (baryon minus lepton) charge. 3 RH neutrinos are required to cancel the anomalies, thus providing neutrino masses via the type-I see-saw. A Z' boson is also present, together with a further scalar for the spontaneous symmetry breaking of the further U(1) factor, at TeV scale.

• Minimal B-L model: gt = 0. This is the "Minimal" version of the model, where the mixing between Z and Z' is set to zero. This choice is set for the .fr and UFO file.

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References

• Please cite ​https://arxiv.org/abs/1811.11452, ​https://arxiv.org/abs/1804.04075 and ​http://arxiv.org/abs/arXiv:0812.4313 for using this version of the model.
• This version
  • ​https://arxiv.org/abs/1811.11452 LHC Constraints on a B-L Gauge Model using Contur
  • ​https://arxiv.org/abs/1804.04075 Long-lived Heavy Neutrinos from Higgs Decays (The study of the parameter space in the neutrino sector)
• Previous version
  • For the pure B-L benchmark see also ​http://arxiv.org/abs/arXiv:0812.4313 Phenomenology of the minimal B-L extension of the Standard model: Z' and neutrinos.
  • ​http://arxiv.org/abs/arXiv:1106.4762 Theoretical constraints on the couplings of non-exotic minimal Z' bosons (full model description in Feynman gauge)
  • Details about available parameter space and experimental/theoretical constraints can be found in:
  • ​http://arxiv.org/abs/arXiv:1002.1939 Tree Level Unitarity Bounds for the Minimal B-L Model
  • ​http://arxiv.org/abs/arXiv:1002.3586 Z' discovery potential at the LHC in the minimal B-L extension of the Standard Model
  • ​http://arxiv.org/abs/arXiv:1004.3039 A Renormalisation Group Equation Study of the Scalar Sector of the Minimal B-L Extension of the Standard Model
  • ​http://arxiv.org/abs/arXiv:1011.2612 Phenomenology of the minimal B−L extension of the Standard Model: the Higgs sector

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Model files

See attachments

*Please use BL_N_UFO when use display modellist at MadGraph5, otherwise it would not be a valid path name.

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Parameter description and user guide

The choice of benchmark model within the class is done by choosing the free parameters below.

Free parameters

• Scalar sector
  • Higgs mixing angle, sa
  • The mass of the Higgs, mh1 and mh2, where mh1 is usually the mass of the SM model Higgs.
• Gauge boson sector
  • The Z' boson mass, mzp
  • The coupling constant of B-L group, g1p
• Neutrino sector
  • The heavy neutrino mass, mnh1, mnh2 and mnh3
  • The light neutrino mass, mnl1, mnl2 and mnl3
  • The neutrino mixing matrix are internal parameter set by Type-I seesaw, please read ​http://arxiv.org/abs/arXiv:0812.4313.
• Please set the decay width of the heavy neutrino, two Higgs and Z' to auto (in MadGraph5 param_card.dat)