Vector-leptoquark model

Authors

Heavy vector boson implementation:

• Michael J. Baker
  • University of Melbourne
  • michael.baker AT unimelb.edu.au
• Javier Fuentes-Martín
  • Universidad de Grandada
  • javier.fuentes AT ugr.de
• Gino Isidori
  • UZH, Zurich
  • isidori AT physik.uzh.ch
• Matthias König
  • Technische Universität München
  • matthias.koenig AT tum.de

Extension with vector-like fermions:

• Darius A. Faroughy
  • Universty of Zürich
  • faroughy AT physik.uzh.ch

• Javier Fuentes-Martín
  • Universidad de Grandada
  • javier.fuentes AT ugr.de

Description of the model

This model is an extension of the SM featuring a vector leptoquark (U₁~(3,1)_2/3), a colored vector (G'~(8,1)₀), and a SM singlet (Z'~(1,1)₀) as new heavy mediators. An extension of the model including vector-like fermions coupling to the new heavy gauge bosons is included.

The implementation of the heavy vector bosons is based on "High-p_T Signatures in Vector-Leptoquark Models" (​arXiv:1901.10480). The extension of the model including vector-like fermions is based on "Maximal Flavour Violation: a Cabibbo mechanism for leptoquarks" (​arXiv:1808.00942) and "Reading the footprints of the B-meson flavor anomalies" (​arXiv:2103.16558). If you use our model file please cite these references.

Model Files

vector_LQ.fr: This is the Feynrules model file for the vector leptoquark.
coloron.fr: This is the Feynrules model file for the vector color-octet.
Zprime.fr: This is the Feynrules model file for the vector singlet.
VLferm.fr: This is the Feynrules model file for the vector-like fermions.

Model Restrictions

Massless.rst: This restriction file sets all the masses and Yukawas to zero, except for the ones of the top quark (necessary to work in the 5 flavor scheme).

Instructions

The model is loaded by merging the model files SM.fr (in StandardModel), vector_LQ.fr, coloron.fr, Zprime.fr and VLferm.fr. Alternatively, one can exclude the model files coloron.fr, Zprime.fr and/or VLferm.fr if the user is not interested in any of these particles.

The implementation allows for the use of the Feynman and unitary gauge in the SM. The switch between the two gauges is achieved via FeynmanGauge = True/False (see StandardModel).
The NP interaction order has been set to 1, the same as QCD.

Examples

model_gen.nb: This is an example Mathematica® notebook that loads the Feynrules model files and calculates the UFO model.
widths.nb: This is an example Mathematica® notebook that loads the Feynrules model files and calculates the Feynman rules and widths of the new vectors.

Interfaces

This model implementation is known to work with the following interfaces:

• FeynArts Interface
• MadGraph Interface

Validation

An alternative Feynrules implementation for the vector leptoquark model alone (but with interactions to left-handed third-generation SM fermions only) is available in ​https://lqnlo.hepforge.org. We have cross-checked our leptoquark implementation (with β_R³³ = 0) against this one, finding a perfect agreement between the two.

UFO model

vector_LQ_UFO.tar: UFO model including the U₁, G' and Z' , and one family of vector-like quarks and leptons with the same quantum numbers as the SM left-handed fermions.