# Exploring Jet Substructure in Semi-visible jets

### Submission summary

 As Contributors: Deepak Kar · Sukanya Sinha Arxiv Link: https://arxiv.org/abs/2007.11597v4 (pdf) Date accepted: 2021-04-16 Date submitted: 2021-03-16 13:47 Submitted by: Kar, Deepak Submitted to: SciPost Physics Academic field: Physics Specialties: High-Energy Physics - Phenomenology

### Abstract

Semi-visible jets arise in strongly interacting dark sectors, where parton evolution includes dark sector emissions, resulting in jets overlapping with missing transverse momentum. The implementation of semi-visible jets is done using the Pythia Hidden valley module to duplicate the QCD sector showering. In this work, several jet substructure observables have been examined to compare semi-visible jets and light quark/gluon jets. These comparisons were performed using different dark hadron fraction in the semi-visible jets (signal). The extreme scenarios where signal consists either of entirely dark hadrons or visible hadrons offers a chance to understand the effect of the specific dark shower model employed in these comparisons. We attempt to decouple the behaviour of jet-substructure observables due to inherent semi-visible jet properties, from model dependence owing to the existence of only one dark shower model as mentioned above.

Published as SciPost Phys. 10, 084 (2021)

Dear editor,

We thank the referees for their reviews, which have certainly improved the quality of the paper. We believe we addressed all the important points to the best of our abilities. As noted by the referees, we view this as a first exploratory study on the subject, with followups planned/possible in many directions.

Sincerely,
Sukanya and Deepak

### List of changes

The major changes are listed:

* The theory section has been expanded, adding the relevant Lagrangian and explaining the parameters of the model.

* The description of signal and background event generation has been expanded, and cross-checks mentioned.

*An angular event display is added for some representative events.

* Added or clarified interpretation of the behaviour seen in plots.

* Figure legends and symbols cleaned up/better explained.

### Submission & Refereeing History

Resubmission 2007.11597v4 on 16 March 2021
Submission 2007.11597v3 on 4 December 2020

## Reports on this Submission

### Anonymous Report 3 on 2021-4-12 (Invited Report)

• Cite as: Anonymous, Report on arXiv:2007.11597v4, delivered 2021-04-12, doi: 10.21468/SciPost.Report.2787

### Report

Thanks for considering my comments and adding some clarity to the paper in the different sections.

My main comment was on the V+jets backgrounds. It would have been nice to see simulations of the processes because it is not clear, for example, that the lepton identification in a densely populated jet would be good enough to reject W+jets entirely . That said, it is fine that these backgrounds are acknowledged in the paragraph you have added to that section.

Perhaps the wording could be slightly softened by (i) removing the 'almost completely' before 'rejected' and (ii) stating that the study of these backgrounds is left to a future publication.

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### Author:  Deepak Kar  on 2021-04-14  [id 1359]

(in reply to Report 3 on 2021-04-12)

Dear referee,

However, the processes with one or more leptons can be almost completely rejected by vetoing events with leptons. The $W \rightarrow \tau_{\textrm{had}}\nu$ and $Z \rightarrow \nu \nu$ processes result in irreducible backgrounds, but since the large radius jets will still come from quarks or gluons, the considerations for multijet events still hold. -
->
However, the processes with one or more leptons can be rejected by vetoing events with leptons. The $W \rightarrow \tau_{\textrm{had}}\nu$ and $Z \rightarrow \nu \nu$ processes result in irreducible backgrounds, but since the large radius jets will still come from quarks or gluons, the considerations for multijet events still hold. A detailed study of these backgrounds is left for future work.

Best regards,
The authors

### Report 2 by Jonathan Butterworth on 2021-4-1 (Invited Report)

• Cite as: Jonathan Butterworth, Report on arXiv:2007.11597v4, delivered 2021-04-01, doi: 10.21468/SciPost.Report.2749

### Report

Thanks for the response and the changes made. I have one remaining request - I agree with your estimate/statement on pile up, but I since this is often considered under "detector effects" I think you should definitely make it clear in the paper that you did not study it (and also say, if you like, that because you used trimmed jets it should not be a big effect).

With that addition (or even without it, if you really don't want to include it!) I would be happy to see this published.

### Requested changes

1 include statement on pile up

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### Author:  Deepak Kar  on 2021-04-14  [id 1357]

(in reply to Report 2 by Jonathan Butterworth on 2021-04-01)

Thanks Jon, we added a line:

The effect of pile-up was not considered as well, but use of groomed jets (trimming was used here) should mitigate the effect of it to a large extent.

### Jonathan Butterworth  on 2021-04-14  [id 1360]

(in reply to Deepak Kar on 2021-04-14 [id 1357])

Thanks. All good to be published from my side.

### Report

Thanks for considering my comments. Let's roll!

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### Author:  Deepak Kar  on 2021-04-14  [id 1358]

(in reply to Report 1 by Tilman Plehn on 2021-03-16)