CMS-PAS-EXO-23-001

CMS-PAS-EXO-23-001
Search for soft unclustered energy patterns in pp collisions at 13 TeV using CMS data scouting
CMS Collaboration
2026-03-14

Abstract: A search for soft unclustered energy patterns (SUEPs) is conducted using proton-proton collision data corresponding to an integrated luminosity of 127 fb$ ^{-1} $ at a center-of-mass energy of 13 TeV, collected via the data scouting stream of the CMS experiment at the LHC. The scouting strategy records only the results of the trigger-level reconstruction in order to enable a lower threshold on the hadronic activity, increasing the acceptance for SUEP signatures, which are predicted by hidden valley models with a large 't Hooft coupling. The observed results are consistent with the standard model background prediction, and the most stringent limits to date are set on the gluon fusion production of heavy scalar mediators resulting in SUEP-like signals.
Links: CDS record (PDF) ; CADI line (restricted) ;

Figures	Summary	References	CMS Publications

Figures
png pdf	Figure 1: A schematic Feynman diagram of the signal model with the SUEP signature.
png pdf	Figure 2: The observed $ n_{\text{constituent}}^{\text{SUEP}} $ distributions for various ranges of $ S^{\text{SUEP}}_{\text{boosted}} $ (left: 0.30 $ \leq S^{\text{SUEP}}_{\text{boosted}} < $ 0.34, middle: 0.34 $ \leq S^{\text{SUEP}}_{\text{boosted}} < $ 0.5, right: $ S^{\text{SUEP}}_{\text{boosted}} \geq $ 0.5), compared to the background prediction in the SR. The pre-fit expected background, the background-only fit result, and two signal models with $ m_{\text{S}} = $ 300 and 1000 GeV are shown. Both signal models have $ m_{\phi} = T_{\text{D}} = $ 3 GeV and $ m_{\text{A}^{\prime}} = $ 1 GeV (fully hadronic decays). The vertical dashed lines mark the boundaries that separate the CRs and the SR.
png pdf	Figure 3: Expected and observed upper limits on the signal cross sections with respect to the mediator masses $ m_{\text{S}} $, comparing this data scouting analysis to the previous offline analysis [29]. Signal models with different values of the temperature, dark hadron mass, and dark photon mass are shown (upper left: $ T_{\text{D}} = $ 2 GeV, $ m_{\phi} = $ 2.0 GeV, $ m_{\text{A}^{\prime}} = $ 1 GeV; upper right: $ T_{\text{D}} = $ 4.0 GeV, $ m_{\phi} = $ 4.0 GeV, $ m_{\text{A}^{\prime}} = $ 0.5 GeV; lower: $ T_{\text{D}} = $ 8.0 GeV, $ m_{\phi} = $ 8.0 GeV, $ m_{\text{A}^{\prime}} = $ 0.7 GeV).
png pdf	Figure 3-a: Expected and observed upper limits on the signal cross sections with respect to the mediator masses $ m_{\text{S}} $, comparing this data scouting analysis to the previous offline analysis [29]. Signal models with different values of the temperature, dark hadron mass, and dark photon mass are shown (upper left: $ T_{\text{D}} = $ 2 GeV, $ m_{\phi} = $ 2.0 GeV, $ m_{\text{A}^{\prime}} = $ 1 GeV; upper right: $ T_{\text{D}} = $ 4.0 GeV, $ m_{\phi} = $ 4.0 GeV, $ m_{\text{A}^{\prime}} = $ 0.5 GeV; lower: $ T_{\text{D}} = $ 8.0 GeV, $ m_{\phi} = $ 8.0 GeV, $ m_{\text{A}^{\prime}} = $ 0.7 GeV).
png pdf	Figure 3-b: Expected and observed upper limits on the signal cross sections with respect to the mediator masses $ m_{\text{S}} $, comparing this data scouting analysis to the previous offline analysis [29]. Signal models with different values of the temperature, dark hadron mass, and dark photon mass are shown (upper left: $ T_{\text{D}} = $ 2 GeV, $ m_{\phi} = $ 2.0 GeV, $ m_{\text{A}^{\prime}} = $ 1 GeV; upper right: $ T_{\text{D}} = $ 4.0 GeV, $ m_{\phi} = $ 4.0 GeV, $ m_{\text{A}^{\prime}} = $ 0.5 GeV; lower: $ T_{\text{D}} = $ 8.0 GeV, $ m_{\phi} = $ 8.0 GeV, $ m_{\text{A}^{\prime}} = $ 0.7 GeV).
png pdf	Figure 3-c: Expected and observed upper limits on the signal cross sections with respect to the mediator masses $ m_{\text{S}} $, comparing this data scouting analysis to the previous offline analysis [29]. Signal models with different values of the temperature, dark hadron mass, and dark photon mass are shown (upper left: $ T_{\text{D}} = $ 2 GeV, $ m_{\phi} = $ 2.0 GeV, $ m_{\text{A}^{\prime}} = $ 1 GeV; upper right: $ T_{\text{D}} = $ 4.0 GeV, $ m_{\phi} = $ 4.0 GeV, $ m_{\text{A}^{\prime}} = $ 0.5 GeV; lower: $ T_{\text{D}} = $ 8.0 GeV, $ m_{\phi} = $ 8.0 GeV, $ m_{\text{A}^{\prime}} = $ 0.7 GeV).
png pdf	Figure 4: Expected and observed exclusions of signal parameters assuming the nominal $ \text{S} $ cross sections for signal models with $ m_{\text{A}^{\prime}} = $ 1 GeV (fully hadronic decays) as a function of $ T_{\text{D}} $ and $ m_{\phi} $ for different $ m_{\text{S}} $ values. The parameter space below the lines is excluded.
png pdf	Figure 5: The $ n_{\text{constituent}}^{\text{SUEP}} $ distributions for various ranges of $ S^{\text{SUEP}}_{\text{boosted}} $ (left: 0.30 $ \leq S^{\text{SUEP}}_{\text{boosted}} < $ 0.34, middle: 0.34 $ \leq S^{\text{SUEP}}_{\text{boosted}} < $ 0.5, right: $ S^{\text{SUEP}}_{\text{boosted}} \geq $ 0.5) in QCD multijet simulation, comparing the extended ABCD prediction to the yield directly from the simulation in the SR. The pre-fit expected background, the background-only fit results, and two signal models with $ m_{\text{S}} = $ 300 and 1000 GeV are shown. Both signal models have $ m_{\phi} = T_{\text{D}} = $ 3 GeV and $ m_{\text{A}^{\prime}} = $ 1 GeV (fully hadronic decays). The vertical dashed lines mark the boundaries that separate the CRs and the SR.
png pdf	Figure 6: Validation of the extended ABCD method (upper left: 2016, upper right: 2017, lower: 2018) in the VR, where signal is negligible compared to background, as shown for signal models with $ m_{\text{S}} = 125, 400 \text{and} $ 1000 GeV, $ m_{\phi} = T_{\text{D}} = $ 3 GeV and $ m_{\text{A}^{\prime}} = $ 1 GeV (fully hadronic decays).
png pdf	Figure 6-a: Validation of the extended ABCD method (upper left: 2016, upper right: 2017, lower: 2018) in the VR, where signal is negligible compared to background, as shown for signal models with $ m_{\text{S}} = 125, 400 \text{and} $ 1000 GeV, $ m_{\phi} = T_{\text{D}} = $ 3 GeV and $ m_{\text{A}^{\prime}} = $ 1 GeV (fully hadronic decays).
png pdf	Figure 6-b: Validation of the extended ABCD method (upper left: 2016, upper right: 2017, lower: 2018) in the VR, where signal is negligible compared to background, as shown for signal models with $ m_{\text{S}} = 125, 400 \text{and} $ 1000 GeV, $ m_{\phi} = T_{\text{D}} = $ 3 GeV and $ m_{\text{A}^{\prime}} = $ 1 GeV (fully hadronic decays).
png pdf	Figure 6-c: Validation of the extended ABCD method (upper left: 2016, upper right: 2017, lower: 2018) in the VR, where signal is negligible compared to background, as shown for signal models with $ m_{\text{S}} = 125, 400 \text{and} $ 1000 GeV, $ m_{\phi} = T_{\text{D}} = $ 3 GeV and $ m_{\text{A}^{\prime}} = $ 1 GeV (fully hadronic decays).

Summary

In summary, this note reports the search for soft unclustered energy patterns (SUEPs) at the LHC using particle-flow scouting data corresponding to an integrated luminosity of 127 fb$ ^{-1}$. This data set is recorded with a lower threshold on the scalar sum of jet transverse momenta, $H_T$, compared to the standard $H_T$ triggers, offsetting the increase in rate by saving limited event content. The characteristic isotropic event shape of SUEP signals is recovered by boosting into the mediator rest frame and selecting particles from only the SUEP candidate, which is chosen as the jet with the highest constituent multiplicity out of the two highest $p_T$ wide jets. The standard model background from quantum chromodynamics multijet processes is estimated from data control regions. The search sets the most stringent limits on a large range of SUEP models with a temperature and dark hadron mass around a few GeV and scalar mediator masses above 125 GeV.

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