CR011 $pp \to W_L W_L W_L W_L; \,\text{experimentally }\, pp \to jj W_L^+/- W_L^+/-$

Longitudinal vector-boson scattering (strong-EWSB sector probe)
Status REVIEWED VERIFIED High Code: NO Priority Low

PDG / equivalent values

Observable Value Year Experiment / source Provenance
Fiducial cross-section upper limit for pp $ \to $ jj $W_L^+/- W_L^+/-$ $\sigma_{fid}(pp \to jj W_L^+/- W_L^+/-) < 0.45 fb (95% CL)$
95% CL (upper_limit)
2025 ATLAS source ↑
Production cross-section upper limit for longitudinally polarized same-sign $W^+/- W^+/-$ pairs $\sigma(pp \to jj W_L^+/- W_L^+/-) < 1.17 fb (95% CL)$
95% CL (upper_limit)
2020 CMS source ↑

Why this constrains the RS scan

In custodial RS and composite-Higgs-like completions, longitudinal VBS tests the sector that unitarizes electroweak symmetry breaking: electroweak KK vectors, scalar resonances, and the pattern of couplings to \(W_L\) and \(Z_L\). This is complementary to colored KK-gluon and vectorlike-partner searches. A VBS excess or exclusion constrains the electroweak/composite resonance sector only after specifying the custodial gauge group, the resonance spectrum, the branching fractions into vector bosons versus tops or composite fermions, and the production mechanism. For the RS scan in this repository, CR011 is not expected to be the leading constraint. The quark-scan methodology note quotes \(\Mkk^{\min}(p50,\gs=3)=47.26~\mathrm{TeV}\) from the low-energy \(\Delta F=2\) scan, while direct electroweak VBS reach remains a few-TeV collider cross-check unless a non-anarchic or protected flavor structure weakens the flavor bound. CR011 is therefore useful as a diagnostic of the strong-EWSB sector and as leverage for non-anarchic RS variants, not as a replacement for the active low-energy flavor constraints.

What's changed since the original paper

atlas\_2017\_arxiv1611\_02428.txt established the LHC same-sign \(WWjj\) VBS/aQGC program at \(8~\mathrm{TeV}\), separating electroweak and strong production regions and introducing VBS-sensitive anomalous-coupling fiducial selections. atlas\_2020\_arxiv2004\_10612.txt extended the VBS program to rare \(ZZjj\) electroweak production, important because neutral diboson scattering tests a different electroweak channel and different background systematics. cms\_2020\_arxiv2009\_09429.txt was the first CMS polarization measurement in same-sign \(WWjj\), setting the \(1.17~\mathrm{fb}\) longitudinal \(WW\) upper limit used above as the historical comparator. atlas\_2024\_arxiv2312\_00420.txt then provided a full Run-2 ATLAS same-sign \(WWjj\) measurement and aQGC interpretation, including differential information and a same-sign \(H^{\pm\pm}\) VBF search. The current polarization-specific improvement is the ATLAS 2025 result promoted here. For EFT/aQGC context, atlas\_2026\_arxiv2603\_18630.txt is the current ATLAS combined interpretation of measurements sensitive to quartic electroweak gauge couplings. Its coefficient intervals are not quoted in this draft because CR011's promoted observable is the direct longitudinal \(WW\) fiducial cross-section limit; adding coefficient-level values would require a separate table extraction and a choice of unitarity/positivity convention.

Validity and model dependence

The ATLAS/CMS limits are fiducial and polarization-template dependent. They assume the Standard Model electroweak VBS topology, leptonic \(W\)-decay event selection, and fitted longitudinal/transverse polarization templates. They do not directly exclude a universal RS \(M_{KK}\) value. A reinterpretation must simulate the chosen custodial-RS spectrum and account for interference with the SM VBS amplitude, resonance widths, acceptance, and decay branching fractions. For aQGC/EFT statements, the interpretation depends on the operator basis, whether one or several Wilson coefficients are profiled, and whether unitarity constraints are imposed. For explicit RS resonances, the assumptions differ again: a narrow electroweak vector resonance decaying visibly to \(VV\) is much more constrained by VBS-like searches than a broad resonance with dominant decays to top partners, heavy fermions, or other composite-sector states. This entry should therefore be treated as collider-sector cross-check information until a dedicated RS likelihood or recast is attached.

Code coverage in this repo

NO. A targeted grep for VBS, longitudinal-polarization, diboson, and aQGC terms across quarkConstraints/, qcd/, flavorConstraints/, neutrinos/, yukawa/, warpConfig/, solvers/, scanParams/, and tests/ returned no matches. Adjacent code evidence shows KK-scale bookkeeping and low-energy flavor evaluation, not collider direct-search filtering: quarkConstraints/scan.py:359 maps \(\Lambda_{\rm IR}\) to \(M_{KK}\), quarkConstraints/scan.py:377 evaluates \(\Delta F=2\) constraints, and scanParams/scan.py:528 passes \(M_{KK}\) into the lepton-flavor-violation check. No ATLAS/CMS, VBS, \(WWjj\), \(ZZjj\), polarization, or collider-likelihood module is present in the searched paths.

Implementation difficulty

HIGH. A live CR011 constraint needs more than a scalar threshold. It requires a collider reinterpretation stack: event generation for the chosen custodial-RS resonance spectrum, showering and detector/selection acceptance, polarization-sensitive templates or an external recast tool such as CheckMATE, MadAnalysis5, or SModelS where applicable, and a likelihood interface for the ATLAS/CMS fiducial regions. EFT/aQGC coefficient comparisons are simpler to record, but mapping them into a concrete RS mass bound is model dependent and not implemented in this repository.

Reason: A live collider-RS constraint needs a full collider likelihood or recast workflow, including signal generation, detector/selection acceptance, polarization templates, model-dependent branching ratios, and external tools such as CheckMATE, MadAnalysis5, or SModelS where applicable.

Key references

ATLAS2025\_LongitudinalWW; CMS2020\_PolarizedSameSignWW; ATLAS2024\_SameSignWWjj; ATLAS2020\_ZZjj; ATLAS2017\_WWjjAQGC; ATLAS2026\_AQGCCombination; PDG2025\_WZQuarticCouplings; Contino2011\_CompositeHiggsResonances.
Source SHAs
8 snapshot(s) tracked in flavor_catalog/processes/collider_rs/CR011.yaml
Access dates
2026-05-17
Worklog
flavor_catalog/worklogs/CR011/
LaTeX source
flavor_catalog/processes/collider_rs/CR011.tex
Anchors generated
2026-05-17T21:55:00-04:00

ATLAS2025:CR011:fiducial_sigma_WLWL_same_sign_upper_limit

https://arxiv.org/abs/2503.11317
accessed 2026-05-17 sha 449b1c2c9f28... snapshot CR011/atlas_2025_arxiv2503_11317.txt RESOLVED
display sigma_fid(pp -> jj W_L^+/- W_L^+/-) < 0.45 fb (95% CL)
RESOLVED
Match snapshot line 27
L24: (expected) significance of the production with at least one longitudinally
L25: polarized W boson is 3.3 (4.0) standard deviations.
L26: 
L27: An observed (expected) 95% confidence level upper limit of 0.45 (0.70) fb is
L28: reported on the fiducial production cross section of two longitudinally
L29: polarized same-sign W bosons.
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

CMS2020:CR011:fiducial_sigma_WLWL_same_sign_upper_limit

https://arxiv.org/abs/2009.09429
accessed 2026-05-17 sha 6ceb6660bd95... snapshot CR011/cms_2020_arxiv2009_09429.txt RESOLVED
display sigma(pp -> jj W_L^+/- W_L^+/-) < 1.17 fb (95% CL)
RESOLVED
Match snapshot line 25
L22: muons, moderate missing transverse momentum, and two jets with a large rapidity
L23: separation and a large dijet mass to enhance the contribution of same-sign
L24: W^+/- W^+/- scattering events. An observed (expected) 95% confidence level
L25: upper limit of 1.17 (0.88) fb is set on the production cross section for
L26: longitudinally polarized same-sign W^+/- W^+/- boson pairs.
L27: 
L28: The electroweak production of same-sign W^+/- W^+/- boson pairs with at least
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.