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arxiv: 1906.08983 · v4 · pith:JLZAOKV4new · submitted 2019-06-21 · ✦ hep-ex

Searching for leptoquarks with the ATLAS detector

Vincent Wai Sum Wong (for the ATLAS Collaboration) This is my paper

Pith reviewed 2026-05-25 18:39 UTC · model grok-4.3

classification ✦ hep-ex
keywords leptoquarksATLASLHCexclusion limitspair productionscalar particlesbeyond Standard Model13 TeV collisions
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The pith

ATLAS excludes first- and second-generation leptoquarks below 1400 and 1560 GeV in the minimal BRW model.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper reports results from searches for pair-produced scalar leptoquarks in 36.1 fb^{-1} of proton-proton collision data collected by the ATLAS detector at 13 TeV. No statistically significant excess above Standard Model predictions appears in the data. The absence of signal allows the experiment to place upper limits on leptoquark masses assuming 100 percent branching to a charged lepton and a quark. First-generation leptoquarks are excluded up to 1400 GeV and second-generation up to 1560 GeV; third-generation limits reach 1000 GeV at extreme branching ratios for both up-type and down-type cases.

Core claim

Results from the latest searches for pair-produced scalar leptoquarks using 36.1 fb^{-1} of pp-collision data recorded by the ATLAS detector at √s = 13 TeV were presented. No statistically significant excess of data over Standard Model prediction is observed. The observed limits on first- (second-) generation leptoquark masses are excluded up to 1400 (1560) GeV in the minimal Buchmüller-Rückl-Wyler model, assuming a leptoquark decay branching ratio of 100% into a charged lepton and a quark. Third generation leptoquark masses are excluded up to 1000 GeV at the highest and lowest decay branching ratios for both up-type and down-type leptoquarks.

What carries the argument

Search for pair-produced scalar leptoquarks in ATLAS detector data, interpreted within the minimal Buchmüller-Rückl-Wyler model with assumed 100% branching ratio to charged lepton plus quark.

If this is right

  • First-generation leptoquarks must be heavier than 1400 GeV if they decay exclusively to a charged lepton and a quark.
  • Second-generation leptoquarks must be heavier than 1560 GeV under the same decay assumption.
  • Third-generation leptoquarks are excluded below 1000 GeV for both the highest and lowest allowed branching ratios in up-type and down-type scenarios.
  • Models that introduce leptoquarks at lower masses are ruled out by the null result in this dataset.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Future runs with higher integrated luminosity could raise these mass limits further if no signal appears.
  • Leptoquarks that decay through non-standard channels or with intermediate branching ratios would require separate dedicated searches.
  • The limits constrain the parameter space of models proposed to explain certain flavor anomalies or other beyond-Standard-Model phenomena.
  • Absence of signals at these masses pushes any new physics involving leptoquarks to higher energy scales accessible only with more data or higher collision energies.

Load-bearing premise

The analysis assumes a 100% branching ratio into a charged lepton plus quark and the validity of the minimal Buchmüller-Rückl-Wyler model for interpreting the absence of excess events.

What would settle it

Observation of a statistically significant excess of events whose kinematic distributions match the expected signature of leptoquark pair production.

Figures

Figures reproduced from arXiv: 1906.08983 by Vincent Wai Sum Wong (for the ATLAS Collaboration).

Figure 1
Figure 1. Figure 1: FIG. 1: Upper exclusion limits at 95% CL on the signal cross-section for pair production of first-generation LQs in the [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2: Upper exclusion limits at 95% CL on the signal cross-section for pair production of second-generation LQs in [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3: Upper exclusion limits at 95% CL on the signal cross-section for third-generation up-type (left) and down-type [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
read the original abstract

Results from the latest searches for pair-produced scalar leptoquarks using 36.1 $\text{fb}^{-1}$ of $pp$-collision data recorded by the ATLAS detector at $\sqrt{s}$ = 13 TeV were presented. No statistically significant excess of data over Standard Model prediction is observed. The observed limits on first- (second-) generation leptoquark masses are excluded up to 1400 (1560) GeV in the minimal Buchm\"uller-R\"uckl-Wyler model, assuming a leptoquark decay branching ratio of 100% into a charged lepton and a quark. Third generation leptoquark masses are excluded up to 1000 GeV at the highest and lowest decay branching ratios for both up-type and down-type leptoquarks.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 1 minor

Summary. The manuscript reports results from searches for pair-produced scalar leptoquarks in 36.1 fb^{-1} of 13 TeV pp collision data recorded with the ATLAS detector. No statistically significant excess over Standard Model predictions is observed. Observed 95% CL mass exclusion limits are presented: 1400 GeV (first generation) and 1560 GeV (second generation) assuming 100% branching ratio to charged lepton plus quark in the minimal Buchmüller-Rückl-Wyler model; third-generation limits reach 1000 GeV at the highest and lowest branching ratios for both up-type and down-type leptoquarks.

Significance. If the background modeling, systematic uncertainties, and statistical procedures are robust, the work supplies updated, model-conditional constraints on leptoquark masses that tighten the allowed parameter space for BSM scenarios. The explicit statement of the 100% (or extremal) branching-ratio assumptions and the minimal BRW model makes the scope of the limits transparent.

minor comments (1)
  1. [Abstract] The abstract states the luminosity and energy but does not repeat the center-of-mass energy when quoting the third-generation limits; a single consistent phrasing would improve readability.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive assessment of the manuscript and their recommendation to accept it.

Circularity Check

0 steps flagged

No significant circularity in experimental limit-setting

full rationale

This is an ATLAS experimental search paper reporting 95% CL mass exclusion limits from a null result (no excess over SM background) in 36.1 fb^{-1} of 13 TeV pp data. The limits are derived by comparing observed data to Standard Model Monte Carlo predictions under explicitly declared assumptions (100% branching ratio to lepton+quark for first/second generation; extremal branching ratios for third generation) within the minimal BRW model. No equations, parameters, or derivations are present that reduce by construction to fitted inputs, self-definitions, or self-citation chains. The result is conditional on the stated model assumptions rather than claiming model-independent coverage, and the derivation chain is self-contained against external data benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The result rests on the assumption of 100% branching ratio and the minimal BRW model; background predictions from the Standard Model are taken as given. No free parameters are fitted to the signal; the limits are set by the absence of excess.

axioms (2)
  • domain assumption Standard Model background predictions accurately describe the data in the signal regions
    The search declares no excess over SM prediction; this is required to interpret the null result as a mass limit.
  • domain assumption Detector simulation and reconstruction efficiencies are correctly modeled
    Limits depend on acceptance and efficiency calculations that rely on Monte Carlo modeling of the ATLAS detector.

pith-pipeline@v0.9.0 · 5657 in / 1451 out tokens · 29464 ms · 2026-05-25T18:39:42.439662+00:00 · methodology

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Reference graph

Works this paper leans on

16 extracted references · 16 canonical work pages

  1. [1]

    Measurement of an Excess of ¯B → D(∗)τ −¯ντ Decays and Implications for Charged Higgs Bosons,

    BaBar Collaboration, “ Measurement of an Excess of ¯B → D(∗)τ −¯ντ Decays and Implications for Charged Higgs Bosons,” Phys. Rev., vol. D88, no. 7, p. 072012, 2013

    work page 2013

  2. [2]

    Measurement of the branching ratio of ¯B → D(∗)τ −¯ντ relative to ¯B → D(∗)ℓ−¯νℓ decays with hadronic tagging at Belle ,

    Belle Collaboration, “ Measurement of the branching ratio of ¯B → D(∗)τ −¯ντ relative to ¯B → D(∗)ℓ−¯νℓ decays with hadronic tagging at Belle ,” Phys. Rev. , vol. D92, no. 7, p. 072014, 2015

    work page 2015

  3. [3]

    Measurement of the ratio of branching fractions B( ¯B0 → D∗+τ −¯ντ)/B( ¯B0 → D∗+µ−¯νµ),

    LHCb Collaboration, “ Measurement of the ratio of branching fractions B( ¯B0 → D∗+τ −¯ντ)/B( ¯B0 → D∗+µ−¯νµ),” Phys. Rev. Lett. , vol. 115, no. 11, p. 111803, 2015. [Erratum: Phys. Rev. Lett.115,no.15,159901(2015)]

    work page 2015

  4. [4]

    Test of lepton universality with B0 →K ∗0ℓ+ℓ− decays,

    LHCb Collaboration, “ Test of lepton universality with B0 →K ∗0ℓ+ℓ− decays,” JHEP, vol. 08, p. 055, 2017

    work page 2017

  5. [5]

    Search for lepton-universality violation in B+ →K +ℓ+ℓ− decays,

    LHCb Collaboration, “ Search for lepton-universality violation in B+ →K +ℓ+ℓ− decays,” Phys. Rev. Lett., vol. 122, no. 19, p. 191801, 2019

    work page 2019

  6. [6]

    LHC Machine ,

    L. Evans and P. Bryant, “ LHC Machine ,” JINST, vol. 3, p. S08001, 2008

    work page 2008

  7. [7]

    ATLAS Collaboration, “ Searches for scalar lepto- quarks and differential cross-section measurements in dilepton-dijet events in proton-proton collisions at a centre-of-mass energy of √s = 13 TeV with the AT- LAS experiment ,” 2019

    work page 2019

  8. [8]

    Searches for third-generation scalar leptoquarks in √s = 13 TeV pp collisions with the ATLAS detector ,

    ATLAS Collaboration, “ Searches for third-generation scalar leptoquarks in √s = 13 TeV pp collisions with the ATLAS detector ,” 2019

    work page 2019

  9. [9]

    Lepto- quarks in Lepton - Quark Collisions ,

    W. Buchmuller, R. Ruckl, and D. Wyler, “ Lepto- quarks in Lepton - Quark Collisions ,” Phys. Lett. , vol. B191, pp. 442–448, 1987. [Erratum: Phys. Lett.B448,320(1999)]

    work page 1987

  10. [10]

    The ATLAS Experiment at the CERN Large Hadron Collider ,

    ATLAS Collaboration, “ The ATLAS Experiment at the CERN Large Hadron Collider ,” JINST, vol. 3, p. S08003, 2008

    work page 2008

  11. [11]

    The anti-kt jet clustering algorithm,

    M. Cacciari, G. P. Salam, and G. Soyez, “The anti-kt jet clustering algorithm,” JHEP, vol. 04, p. 063, 2008

    work page 2008

  12. [12]

    Search for a scalar partner of the top quark in the jets plus missing transverse momentum final state at √s=13 TeV with the ATLAS detector,

    ATLAS Collaboration, “ Search for a scalar partner of the top quark in the jets plus missing transverse momentum final state at √s=13 TeV with the ATLAS detector,” JHEP, vol. 12, p. 085, 2017

    work page 2017

  13. [13]

    ATLAS Collaboration, “ Search for top-squark pair production in final states with one lepton, jets, and missing transverse momentum using 36 fb −1 of √s = 13 TeV pp collision data with the ATLAS detector ,” JHEP, vol. 06, p. 108, 2018

    work page 2018

  14. [14]

    Search for supersymmetry in events with b-tagged jets and missing transverse mo- mentum in pp collisions at √s = 13 TeV with the ATLAS detector,

    ATLAS Collaboration, “ Search for supersymmetry in events with b-tagged jets and missing transverse mo- mentum in pp collisions at √s = 13 TeV with the ATLAS detector,” JHEP, vol. 11, p. 195, 2017

    work page 2017

  15. [15]

    Search for top squarks de- caying to tau sleptons in pp collisions at √s = 13 TeV with the ATLAS detector ,

    ATLAS Collaboration, “ Search for top squarks de- caying to tau sleptons in pp collisions at √s = 13 TeV with the ATLAS detector ,” Phys. Rev., vol. D98, no. 3, p. 032008, 2018

    work page 2018

  16. [16]

    Search for resonant and non- resonant Higgs boson pair production in the b¯bτ +τ − decay channel in pp collisions at √s = 13 TeV with the ATLAS detector ,

    ATLAS Collaboration, “Search for resonant and non- resonant Higgs boson pair production in the b¯bτ +τ − decay channel in pp collisions at √s = 13 TeV with the ATLAS detector ,” Phys. Rev. Lett. , vol. 121, no. 19, p. 191801, 2018. [Erratum: Phys. Rev. Lett.122,no.8,089901(2019)]. W edE1410

    work page 2018