SciPost Submission Page

New sensitivity of current LHC measurements to vector-like quarks

by A. Buckley, J. M. Butterworth, L. Corpe, D. Huang, P. Sun

Submission summary

As Contributors: Andy Buckley · Jonathan Butterworth · Louie Corpe
Arxiv Link: https://arxiv.org/abs/2006.07172v1 (pdf)
Date submitted: 2020-06-15
Submitted by: Corpe, Louie
Submitted to: SciPost Physics
Discipline: Physics
Subject area: High-Energy Physics - Phenomenology
Approaches: Computational, Phenomenological

Abstract

Quark partners with non-chiral couplings appear in several extensions of the Standard Model. They may have non-trivial generational structure to their couplings, and may be produced either in pairs via the strong and EM interactions, or singly via the new couplings of the model. Their decays often produce heavy quarks and gauge bosons, which will contribute to a variety of already-measured "Standard Model" cross-sections at the LHC. We present a study of the sensitivity of such published LHC measurements to vector-like quarks, first comparing to limits already obtained from dedicated searches, and then broadening to some so-far unstudied parameter regions.

Current status:
Editor-in-charge assigned


Submission & Refereeing History

Submission 2006.07172v1 on 15 June 2020

Reports on this Submission

Anonymous Report 1 on 2020-6-23 Invited Report

Strengths

1- Broad results, complementary to standard analyses
2- The methodology used can be easily exported to other experimental analyses and have significant positive implications.

Weaknesses

1- No significant weaknesses

Report

The article uses the impressive Rivet+Contur framework to study a vast array of LHC measurements and searches on models with new vector-like quarks. Searches (or measurements) that are not specifically designed for these models, and quite often control regions in such searches, are shown to have a significant reach. They are often complementary to the more specific searches and therefore an excellent test of these models. Furthermore, in some cases they reach essentially make the specific searches redundant. The automated process involved allows one (and in particular big experimental collaborations) to explore the improvement that a specific search has on particular models over the implications of generic measurements or searches. In my view, this is a very strong work that deserves to be published in SciPost Physics and will likely have a significant impact on the field. I have only some minor, almost aesthetic, comments on the current draft:

1- The fermionic arrow corresponding to $Q_j$ in Fig. 1 (e) should point in the opposite direction.
2- The sentence in the middle of page 5 "... production of any flavour of VLQ in association with a V becomes suppressed with respect to pair-production, ..." can lead to misunderstanding from the reader as it does not take into account the phase space suppression in pair production versus single production, which I know the authors are aware of because they comment on this in section 5. Maybe a short comment here would be useful.
3- I'm not sure I fully understand the comment about the suppression of the $T+q$ and $B+q$ channels mentioned at the top of page 6. The comment about the u and d Yukawa couplings would suggest a suppression of several orders of magnitude. Is that true? Is there no $Z$ contribution? Aren't the charged current channels also suppressed by $\xi$ factors?

Requested changes

1- I would suggest to fix Fig 1 (e) and maybe clarify my points 2 and 3 in the report.

  • validity: top
  • significance: top
  • originality: top
  • clarity: top
  • formatting: perfect
  • grammar: perfect

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