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Simplified dark matter top-quark interactions at the LHC

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Ulrich Haisch, Emanuele Re

High Energy Physics - Phenomenology · Submitted 2 Mar 2015 · 59 references

Pith's verdict: A careful, useful channel-by-channel comparison that establishes mono-jet as the strongest run-1 handle on spin-0 dark matter coupling to tops, with the EFT-failure numbers being the most reusable result.

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arXiv ID1503.00691 (version 4)
Pith IDB6PAXGNJ, Pith's permanent record of this paper and its review
CitationEmanuele Re, Ulrich Haisch. "Simplified dark matter top-quark interactions at the LHC." arXiv:1503.00691 (2015). https://pith.science/paper/B6PAXGNJ
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The paper

The paper claims

For dark matter that couples to top quarks, the mono-jet search is the sharpest LHC probe, and it stays sharpest at 14 TeV.

The reading

The paper asks a practical question: among the LHC searches that look for dark matter recoiling against visible particles, which one actually constrains dark matter coupled to top quarks most tightly? The authors answer it inside a four-parameter simplified model — a dark matter mass, a mediator mass, and one coupling each to the dark and visible sectors — with the mediator's decay width computed from those parameters rather than tuned by hand, and with the mediator's quark couplings tied to quark masses by minimal flavour violation. Recasting the run-1 mono-jet search and the three missing-energy-plus-top-pair channels onto that model, they find mono-jet wins: suppression scales above roughly 145 GeV for the scalar and 160 GeV for the pseudo-scalar, for dark matter lighter than about 100 GeV, against about 120 GeV from the single-lepton top-pair channel and about 90 GeV from the di-lepton and fully hadronic ones. The same ordering is projected to hold at 14 TeV, where the mono-jet reach is limited by background systematics rather than statistics. The wider payoff is a warning: effective-field-theory limits on top-quark couplings are not trustworthy at these energies, because the infinite-top-mass approximation overstates the true mono-jet rate by factors of 4 to 32 already at 8 TeV.

What carries the argument

The load-bearing object is the simplified model itself: a colourless scalar or pseudo-scalar mediator with a dark matter coupling and a Yukawa-like coupling to quarks proportional to $m_q/v$, with the mediator width computed from the partial widths into dark matter, quarks and gluons rather than treated as a free parameter. That choice is what makes the exclusion contours meaningful, because the width grows quadratically with the dark matter coupling and the effective-field-theory comparison breaks down precisely where the resonance becomes broad. On the collider side the machinery is a matched simulation chain: a next-to-leading-order-accurate generator for the loop-induced mono-jet signal with the full top-quark mass dependence, and leading-order event generation for the top-pair channels, both showered and hadronised, then subjected to the published signal-region cuts of each search. The comparison of limits across channels is then a like-for-like recast onto a common parameter space, which is what allows the ranking to be stated at all.

Extended reading notes

Core claim

The central claim is a ranking: for spin-0 $s$-channel mediators that couple to top quarks under minimal flavour violation, the LHC mono-jet search sets stronger 95% CL limits on the suppression scale than any missing-energy-plus-top-pair channel, and this holds for both scalar and pseudo-scalar mediators and persists at 14 TeV. The quoted numbers are $145$ GeV and $160$ GeV for the scalar and pseudo-scalar suppression scales at dark matter masses below about 100 GeV, compared with roughly 120 GeV from the single-lepton top-pair channel and 90 GeV from the di-lepton and fully hadronic channels. The authors also show that the exact exclusions differ in shape from the effective-field-theory ones: the naive validity criterion that the mediator be heavier than twice the dark matter mass fails to reproduce the real contours, and depending on the channel the effective description can be either too aggressive or too conservative. A further reported result is that the infinite-top-mass limit badly overestimates the mono-jet rate, by factors of 4 to 32 at 8 TeV and 19 to 72 at 14 TeV, which undermines the practice of importing a Higgs-plus-jet $K$-factor into this channel. A closing note records that a competing mono-jet analysis had omitted the jet veto, inflating its cross sections by at least a factor of three, and that residual quantitative disagreements with the corrected version remain unexplained.

Load-bearing premise

The ranking depends on comparing the mono-jet channel, simulated at leading order with showering, against the top-pair channels simulated at leading order without the next-to-leading-order corrections the authors estimate at about 1.6 and 1.2 respectively, so the two channels are effectively compared at different perturbative accuracy.

Editorial extensions

If this is right

  • For dark matter coupled to top quarks through a spin-0 mediator, run-2 and upgrade searches should prioritise the mono-jet channel, since it excludes more parameter space than the top-pair channels at every mediator and dark matter mass shown.
  • Effective-field-theory limits on top-quark dark matter couplings should not be quoted as if they were the exact answer at 8 or 14 TeV; the exact simplified-model exclusion differs in shape and can be either stronger or weaker depending on the channel.
  • Because the mono-jet reach at 14 TeV saturates with luminosity, further gains there require better control of irreducible Standard Model backgrounds rather than more data.
  • The top-pair channels remain worth pursuing: for scalar mediators in regions where off-shell production dominates, they can probe parameter space that mono-jet does not, and they become competitive only at the high-luminosity upgrades.
  • Even with the full run-1 dataset, weakly coupled realisations with visible-sector couplings below order one are not excluded, so the simplified models tested here remain viable at weak coupling.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the mono-jet advantage is as robust as claimed, the natural next step is a dedicated run-2 mono-jet analysis optimised for the top-loop topology rather than for generic contact interactions, since the existing signal regions were not designed for it.
  • The observation that the ratio of showered to fixed-order cross sections is nearly flat across the parameter space suggests the whole exclusion scan could be reduced to a small number of expensive simulations plus fast fixed-order evaluations, which would make wider parameter scans routine.
  • The paper's own remark that two-particle correlations among top decay products carry information about the Lorentz structure of the coupling points to a measurement that could distinguish scalar from pseudo-scalar mediators, which none of the counting experiments described here can do.
  • The unexplained residual disagreement with the corrected competing analysis, specifically the failure of its contours to reach the mediator-equals-twice-dark-matter-mass line, is a checkable discrepancy that a third party could settle by rerunning both chains on identical cuts.
Original abstract

Stringent limits on the interactions between dark matter (DM) and the standard model can be set by studying how initial-state or final-state particles recoil against missing transverse energy (MET). In this work, we improve, extend and correct LHC constraints on the interactions between DM and top quarks that are mediated by the exchange of spin-0 s-channel resonances. A comparison of the LHC run-1 sensitivity of the two main search channels is presented, which shows that mono-jet searches are typically more restrictive than the MET + tbar t searches. We furthermore explore the reach of the 14 TeV LHC. The collider constraints are compared to the restrictions arising from direct and indirect detection as well as the DM relic abundance, and we also reflect on effective field theory interpretations of the LHC exclusions.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 4,306 input tokens, $0.0002 reported.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.17 · human participants 0.01 · controlled comparison 0.17 · randomized assignment 0.01 · states quantitative result 0.09 · compares with prior results 0.94 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v4. Results and the main claim are underlined; .

Stringent limits on the interactions between dark matter (DM) and the standard model can be set by studying how initial-state or final-state particles recoil against missing transverse energy (MET). In this work, we improve, extend and correct LHC constraints on the interactions between DM and top quarks that are mediated by the exchange of spin-0 s-channel resonances. A comparison of the LHC run-1 sensitivity of the two main search channels is presented, which shows that mono-jet searches are typically more restrictive than the MET + tbar t searches. We furthermore explore the reach of the 14 TeV LHC. The collider constraints are compared to the restrictions arising from direct and indirect detection as well as the DM relic abundance, and we also reflect on effective field theory interpretations of the LHC exclusions.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 Stringent limits on the interactions between dark matter (DM) and the standard model can be set by studying how initial-state or final-state particles recoil against missing transverse energy (MET). background 1.00 0.07 0.04 asserted 0.83
s1 In this work, we improve, extend and correct LHC constraints on the interactions between DM and top quarks that are mediated by the exchange of spin-0 s-channel resonances. contribution 1.00 0.93 0.17 asserted 0.99
s2 A comparison of the LHC run-1 sensitivity of the two main search channels is presented, which shows that mono-jet searches are typically more restrictive than the MET + tbar t searches. result 0.99 0.87 0.33 asserted 0.95
s3 We furthermore explore the reach of the 14 TeV LHC. contribution 0.93 0.83 0.04 asserted 0.52
s4 The collider constraints are compared to the restrictions arising from direct and indirect detection as well as the DM relic abundance, and we also reflect on effective field theory interpretations of the LHC exclusions. contribution 0.56 0.86 0.12 asserted 0.81

What kind of paper the classifier reports this is: simulation study 0.51 · evidence from analysis of existing data 0.80.

What was examined, and what was not

sources read
  • arXiv listing abstract v4
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. Examples of Feynman diagrams with an insertion of Ot S that contribute to a E/ T +j (top left), E/ T +tt¯ (→ 2j ¯bb) (top right), E/ T +tt¯ (→ jblν) (bottom left) or a E/ T +tt¯ (→ ¯bl−νbl ¯ +ν) (bottom right) signal. The operator insertions are indicated by yellow blobs, while the regular SM vertices are represented by black dots. Integrating out the top quark generates an effective interaction between DM and gluons. At the one-loop level, one obtains OG = αs 12πΛ3 S χχ G ¯ a µνG a,µν , OGe = αs 8πΛ3 P χγ¯ 5χ Ga µνGea,µν , (2.7) by employing the Shifman-Vainshtein-Zakharov…
Figure 2. Lower 95% CL limits on the suppression scales ΛS (left) and ΛP (right) that derive from the mono-jet (red), E/ T +tt¯ (→ 2j ¯bb) (blue), E/ T +tt¯ (→ jblν) (green) and E/ T +tt¯ (→ ¯bl−νbl ¯ +ν) (yel￾low) searches after LHC run-1. The widths of the bands reflect scale uncertainties. widths of the coloured bands illustrate the impact of scale variations. The corresponding relative uncertainties amount to around ±8% and ±6% in the case of the mono-jet and the E/ T + tt¯ signals, respectively. We see that for both the scalar and the pseudo-scalar operator Ot S and Ot P , the bound (3
Figure 3. Projected lower 95% CL limits on ΛS (left) and ΛP (right) from mono-jet (red) and E/ T + tt¯ (→ jblν) (green) searches at the 14 TeV LHC. The shown predictions assume an integrated luminosity of 25 fb−1 . Scale uncertainties are indicated by the widths of the coloured bands. From (2.7) one would hence expect that for a given mono-jet cross section the restrictions on ΛP are by a factor of (3/2)1/3 ' 1.14 better than the limits on ΛS, and this is to very good approximation what one finds. Finally, realise that for mχ & 100 GeV the limits on ΛS all fall off faster than the bounds on…
Figure 4. The quantities ∆S (left panel) and ∆P (right panel) as a function of the DM mass. The solid lines indicate the results that apply in the case of the 8 TeV mono-jet searches, while the dashed curves correspond to our future projections based on 25 fb−1 of 14 TeV data. 3.4 Infinite top-quark mass limit The mono-jet limits on ΛS,P have been derived in the last two sections by employing the exact results for the one-loop pp → E/ T + j amplitudes, but integrating out the mediators that induce the DM-SM interactions. In the following, we compare these bounds to those that one obtains in…
Figure 6. Present mono-jet exclusion regions at 95% CL for pseudo-scalar mediators. The latest Fermi-LAT 95% CL bound on the total velocity-averaged DM annihilation cross section hσvχi is indicated by the solid blue curves. Apart from this the same colour coding and choice of parameters as in
Figure 9. Exclusion contours at 95% CL for scalar mediators following from hypothetical mea￾surements of a E/ T + j signal (red regions) and studies of the E/ T + tt¯ single-lepton channel (green regions). The shown predictions assume 25 fb−1 of 14 TeV LHC data. In the g S SM –g S DM plane (upper left panel), we employed mχ = 100 GeV and MS = 300 GeV, while in the gS –mχ plane (upper right panel) we have set gS = g S SM = g S DM and MS = 300 GeV. The results in the gS –MS plane (lower left panel) correspond to the same couplings and mχ = 100 GeV, while in the MS –mχ plane (lower right panel)…
Figure 10. Exclusion contours at 95% CL for pseudo-scalar mediators following from hypothetical measurements of a E/ T +j signal (red regions) and studies of the E/ T +tt¯single-lepton channel (green regions). The shown predictions assume 25 fb−1 of 14 TeV LHC data. The colour coding and choice of parameters is identical to the one used in
Figure 11. Contour plot of the ratio of the LOPS and LO cross sections for mono-jet production as a function of the mediator mass MS (MP ) and the DM mass mχ. The left (right) panel shows the results for a scalar (pseudo-scalar) mediator at 8 TeV (14 TeV). presented in [22]. Notice that these findings strongly suggest that in the mono-jet case, the signal acceptance is a rather flat function in both parameter and theory space. From the above discussion it should be clear that to achieve accurate results it is sufficient to calculate the ratio between the fiducial cross sections before and…

Showing 8 of the paper's 11 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:1503.00691 by the authors.

References
How later papers used it

64 later papers cite it

Evidence: substantial. 54 of the citing papers share no author with it, and 10 of those carry a confident label from Pith's citation classifier.

Pith read 13 of the 96 citing sentences, choosing only those whose citation markers point at this paper alone, and wrote the paraphrases from them. The summary, the counts, the evidence level, the links and the quotes come from code; the summary counts the papers listed below. A later paper is listed under a label when Pith's citation classifier gives one of its sentences that label at probability 0.8 or more (0.95 for support), Pith's reading finds that the citing paper itself did it, and a second check confirms the paraphrase against the sentence. This section lists uses only. It does not list criticism or disagreement, so their absence here says nothing about how the paper has been received. Papers that share an author with this one are listed apart, under "By the same authors". A quote is the citing authors' own sentence, shown when their paper's licence is CC BY, CC BY-SA or CC0. JSON

Uses its method or tool 1 of 5 papers with this label
How the literature uses it

64 arXiv papers cite this in 96 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 53 sentences without a confident label

Builds on it 1 paper
  • We now turn to invisible Higgs states produced in association with top quarks, where limits at 8 TeV have been obtained [ref] by reinterpretation of a CMS stop search [ref] , and perform an optimized projection for the reach of the 14 TeV LHC.

    The Hunt for the Rest of the Higgs Bosons · $t t̅+$ at 14 TeV · 0.91

Uses its method or tool 5 papers
Uses its data or values 1 paper
Compares with it 6 papers
Cites it as support 2 papers
Cites it as background 24 papers

What it cites · 55 sentences without a confident label

Contests 1 paper
  • This means that taking a $K$ factor obtained from Higgs plus jet production to upgrade the LOPS mono-jet cross sections to the NLO level (as done in [ref] ) is hard to defend from a theoretical point of view.

    Scalar Simplified Models for Dark Matter · Infinite top-quark mass limit · contest 0.79

Builds on 1 paper
Uses the method or tool of 11 papers
Uses data or values from 4 papers
Compares with 7 papers
Cites as support 1 paper
Cites as background 11 papers
  • Constraints from mono-jet searches on the scalar and pseudo-scalar DM-quark interactions $O_S,P^q$ involving the light quark flavours as well as the gluonic operators $O_G$ have been discussed in detail in [ref] , while analyses of the bounds on $O_S,P^b$ arising from $E_T + b̅ b$ final states have been carried out in [ref] .

    Search for dark matter in events with heavy quarks and missing transverse momentum in $pp$ collisions with the ATLAS detector · EFT description · 0.89

  • Constraints from mono-jet searches on the scalar and pseudo-scalar DM-quark interactions $O_S,P^q$ involving the light quark flavours as well as the gluonic operators $O_G$ have been discussed in detail in [ref] , while analyses of the bounds on $O_S,P^b$ arising from $E_T + b̅ b$ final states have been carried out in [ref] .

    Next-to-Leading Order Predictions for Dark Matter Production at Hadron Colliders · EFT description · 0.89

  • Constraints from mono-jet searches on the scalar and pseudo-scalar DM-quark interactions $O_S,P^q$ involving the light quark flavours as well as the gluonic operators $O_G$ have been discussed in detail in [ref] , while analyses of the bounds on $O_S,P^b$ arising from $E_T + b̅ b$ final states have been carried out in [ref] .

    Probing dark matter couplings to top and bottom at the LHC · EFT description · 0.89

Discussion

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