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Probing a leptophobic top-colour model with cross section measurements and precise signal and background predictions: a case study

by M. M. Altakach, J. M. Butterworth, T. Ježo, M. Klasen, I. Schienbein

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Submission summary

Authors (as registered SciPost users): Mohammad Mahdi Altakach · Jonathan Butterworth
Submission information
Preprint Link:  (pdf)
Date accepted: 2022-11-28
Date submitted: 2022-09-13 11:59
Submitted by: Altakach, Mohammad Mahdi
Submitted to: SciPost Physics Core
Ontological classification
Academic field: Physics
  • High-Energy Physics - Phenomenology
Approaches: Experimental, Phenomenological


The sensitivity of particle-level fiducial cross section measurements from ATLAS, CMS and LHCb to a leptophobic top-colour model is studied. The model has previously been the subject of resonance searches. Here we compare it directly to state-of-the-art predictions for Standard Model top quark production and also take into account next-to-leading order predictions for the new physics signal. We make use of the CONTUR framework to evaluate the sensitivity of the current measurements, first under the default CONTUR assumption that the measurement and the SM exactly coincide, and then using the full SM theory calculation for $t\bar{t}$ at next-to-leading and next-to-next-to-leading order as the background model. We derive exclusion limits, discuss the differences between these approaches, and compare to the limits from resonance searches by ATLAS and CMS.

Published as SciPost Phys. Core 6, 014 (2023)

Reports on this Submission

Anonymous Report 2 on 2022-10-26 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:2111.15406v2, delivered 2022-10-26, doi: 10.21468/SciPost.Report.5986


Detailed study of the impact of NNLO SM predictions to extract exclusion limits on BSM physics


1. General analysis limited to a single specific model
2. Exclusion limits significantly weaker than those of dedicated direct searches


The authors test the CONTUR kit ability in putting exclusion limits on the parameter space of an extra neutral Z' (mass, width), using data collected by the ATLAS and CMS experiments at LHC. Due to the selective leptophobic character of the new gauge vector boson, the signal arises from Z' hadronic decays.

The authors implement different estimates of the SM background within the CONTUR framework. The standard approach of CONTUR (SM predictions matching the existing data), is compared to theory-driven estimates (SM background evaluated from the theory at NLO or at NNLO). The impact of more precise SM predictions is seen in the increased limits when NNLO predictions are used compared to NLO and to the standard CONTUR setting.

The paper is well written. The analysis is clearly and comprehensively described. The results are interesting, but weakened by the significantly better limits obtained by the experimental collaborations in dedicated direct searches. In my opinion the results of the paper are not sufficiently innovative to meet the strict acceptance criteria of SciPost Physics. Nevertheless, the paper contains interesting enough information to allow publication in SciPost Physics Core.

Requested changes

The paper can be published in its present form.

  • validity: good
  • significance: good
  • originality: good
  • clarity: high
  • formatting: excellent
  • grammar: excellent

Anonymous Report 1 on 2022-10-21 (Invited Report)


Clear demonstration of the impact of using higher-order theory predictions for the Standard Model background in an analysis performed with the CONTUR toolkit.


Limited scope of the results.


This paper was initially submitted to SciPost Physics. The previous referee report recommended it for publication in SciPost Physics Core and asked the authors to address a number of minor points (see

The authors have implemented all the requested changes and have commented on them in their answers to the initial referee report. All points raised in the initial report have been addressed in a satisfactory manner. This has further improved the paper and I recommend it for publication in SciPost Physics Core.

  • validity: high
  • significance: good
  • originality: good
  • clarity: high
  • formatting: excellent
  • grammar: perfect

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