SciPost Submission Page
Staying on Top of SMEFT-Likelihood Analyses
by Nina Elmer, Maeve Madigan, Tilman Plehn, Nikita Schmal
Submission summary
| Authors (as registered SciPost users): | Nina Elmer · Tilman Plehn · Nikita Schmal |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2312.12502v2 (pdf) |
| Date submitted: | 2024-05-16 14:39 |
| Submitted by: | Elmer, Nina |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
|
| Approach: | Phenomenological |
Abstract
We present a new global SMEFT analysis of LHC data in the top sector. After updating our set of measurements, we show how public ATLAS likelihoods can be incorporated in an external global analysis and how our analysis benefits from the additional information. We find that, unlike for the Higgs and electroweak sector, the SMEFT analysis of the top sector is mostly limited by the correlated theory uncertainties. Finally, we present the first global SFITTER analysis combining the top and electroweak-Higgs sectors.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
Reports on this Submission
Strengths
1- The study uses public likelihood information for the first time in a SMEFT interpretation.
2- A rigorous statistical interpretation is performed, using the well-established SFitter tool.
3- The impact of various systematic uncertainties is quantified, helping to identify where the most impartant effects lie in the interpretation of top quark data.
Weaknesses
1- Some of the explanations are a bit too brief, e.g., the actual implementation of the systematic uncertainties for the datasets used and the details of the information used in constructing the HistFactory likelihoods.
2- The public likelihoods should contain enough information to treat the impact of EFT effects in the background yields. It would have been nice to quantify the impact of those.
Report
The paper is short but achieves its intended goal, showing a proof of principle for using public likelihood information in SMEFT analyses. This is something that has been talked about for many years but has not been possible until recently. It will hopefully motivate experimental collaborations to consistently report their results in this way. The in-depth study of systematic uncertainties for top sector SMEFTinterpretations is timely and will be useful to the community. I am satisfied that the paper meets the threshold for publication in SciPost Physics.
Requested changes
1- p4, above equation (6): The 4-fermion operators are described as having a "chirality flip". I would typically reserve that description for scalar and tensor current operators that directly connect left and right-handed fields.
2- p5, before Sec. 2.2. Four-heavy operaators have also been shown to have an impact on ttbar production. While this impact is likely modest, it should be mentioned for context.
3- p6, why is only tt-gamma not inclued at NLO? It should be discussed whether this is due to a technical challenge or limitation, or simply a choice.
4- p7: I don't understand the statement that a minimum of 10%(2%) scale uncertainties are enforced for total rates (differential cross sections). Does this mean that reported scaled unceertainties below this amount are artificially inflated? Please explain this part more clearly and justify the choice.
5- p8, Fig. 1: I recommend placing a lower panel on each subfigure showing the ratio of the SMEFT prediction to the SM, to clearly show therelative impact of the operator.
6- p9/10, before Sec. 3: The treatment of flat likelihoods by the profile likelihood method is discussed here. What does the Bayesian marginlisation do here? I believe it is briefly discussed later on when both methods are actually compared, but since you summarise one here, it would be clearer if the other were also summarised.
7- p10, Tab. 4: The table is not sufficiently explained in the text/caption. Symbols are undefined such as alpha, gamma, lambda which makes the whole discussion/explanation of the systematics modelling unclear.
8- p18, below Fig. 11: The conclusion on correlated systematics is that they have a negligible impact. Yet it is later stated that they cannot be ignored, which is a bit contradictory. Perhaps rephrase this or remove this statement, since it seems like they can be ignored in this case.
9- p19, before Sec. 4.3: Can you say anything about the impact of neglecting correlations between theory uncertainties? Or is this not possible due to the way that you implement them in SFitter? I believe that theory uncertainty correlations are often neglected in other works, so it would be interesting to see their impact, given the fact that theory errors dominate in this study.
Recommendation
Ask for minor revision
Strengths
1 - first usage of public likelihoods
2 - study of the impact of systematic uncertainties
3 - careful study of the reproducibility of the results from externally provided inputs
Weaknesses
1 - The language, overall, should be improved
2 - Too few details on the concrete model and the uncertainty implementation in the combination
3 - The results from the combined SMEFT analyses should be better integrated into the narrative
4 - A question about the validity of the statistical procedure related to the Markov chain should be addressed
Report
The paper draft fits the journal's scope.
Requested changes
Please see the attached text file. Since several suggestions can potentially change the results, I mark it as a "major revision".
Recommendation
Ask for major revision