CMS-PAS-EXO-25-007

CMS-PAS-EXO-25-007
Search for soft unclustered energy patterns produced in association with a W or Z boson in proton-proton collisions at 13 TeV
CMS Collaboration
2025-11-28

Abstract: A search for soft unclustered energy patterns (SUEPs) produced in association with a W or Z boson is presented. The analysis is based on proton-proton collision data corresponding to an integrated luminosity of 138 fb$ ^{-1} $ collected between 2016 and 2018 with the CMS detector at the LHC. Final states with one charged lepton and missing transverse momentum compatible with a leptonic W boson decay or two charged leptons compatible with a leptonic Z boson decay and a high multiplicity of low-momentum tracks are explored for the first time. The results show no significant excess over the standard model expectation. Upper limits are set on the branching fraction of the 125 GeV Higgs boson decay to a SUEP.
Links: CDS record (PDF) ; CADI line (restricted) ;

Figures	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Distributions of $ n_{\text{constituent}}^{\text{SUEP}} $ in the extended ABCD subregions A--I in the SR for the WH (upper) and ZH (lower) channels, showing the observed data, the predictions from the background-only fit, and several signal hypotheses. The distribution is split into $ S^{\text{SUEP}}_{\text{boosted}} $ ($ p_{\mathrm{T}}^{\text{j}_{1}} $) bins for the WH (ZH) channel.
png pdf	Figure 1-a: Distributions of $ n_{\text{constituent}}^{\text{SUEP}} $ in the extended ABCD subregions A--I in the SR for the WH (upper) and ZH (lower) channels, showing the observed data, the predictions from the background-only fit, and several signal hypotheses. The distribution is split into $ S^{\text{SUEP}}_{\text{boosted}} $ ($ p_{\mathrm{T}}^{\text{j}_{1}} $) bins for the WH (ZH) channel.
png pdf	Figure 1-b: Distributions of $ n_{\text{constituent}}^{\text{SUEP}} $ in the extended ABCD subregions A--I in the SR for the WH (upper) and ZH (lower) channels, showing the observed data, the predictions from the background-only fit, and several signal hypotheses. The distribution is split into $ S^{\text{SUEP}}_{\text{boosted}} $ ($ p_{\mathrm{T}}^{\text{j}_{1}} $) bins for the WH (ZH) channel.
png pdf	Figure 2: Interpretation of the results for the decay of the 125 GeV Higgs boson mediator to a SUEP, for signal models with dominantly hadronic decays. The observed upper limit from the combination of the WH and ZH channels is shown as a function of the signal model parameters $ m_{\phi} $ and $ \log_{2}(T_{\text{D}}/m_{\phi}) $, along with the contours at which the observed or median expected upper limit on the branching fraction equals unity. The previous best limits for unity branching fraction from the gluon fusion channel [13] are also shown.
png pdf	Figure 3: 95% CL upper limits on the signal yield from the model-agnostic fit for different minimum $ n_{\text{constituent}}^{\text{SUEP}} $ values in the WH and ZH channels.
png pdf	Figure 4: As Fig. 2, for signal models with fully hadronic (left) and dominantly leptonic (right) decay modes.
png pdf	Figure 4-a: As Fig. 2, for signal models with fully hadronic (left) and dominantly leptonic (right) decay modes.
png pdf	Figure 4-b: As Fig. 2, for signal models with fully hadronic (left) and dominantly leptonic (right) decay modes.
png pdf	Figure 5: Distributions of $ n_{\text{constituent}}^{\text{SUEP}} $ in the extended ABCD method subregions for the validation regions: the SER for PR-WH (upper) and the SER and SDRs for PR-ZH (lower).
png pdf	Figure 5-a: Distributions of $ n_{\text{constituent}}^{\text{SUEP}} $ in the extended ABCD method subregions for the validation regions: the SER for PR-WH (upper) and the SER and SDRs for PR-ZH (lower).
png pdf	Figure 5-b: Distributions of $ n_{\text{constituent}}^{\text{SUEP}} $ in the extended ABCD method subregions for the validation regions: the SER for PR-WH (upper) and the SER and SDRs for PR-ZH (lower).

Summary

In summary, this note presents the first search for final states with a large-radius jet composed of low-momentum, spherically distributed particles---a soft unclustered energy pattern or SUEP---and a massive vector boson. Events are selected at trigger level based on the presence of one or two charged leptons arising from the leptonic decays of the W or Z boson. This strategy improves the sensitivity of the search to Higgs boson mediators by up to two orders of magnitude in the branching fraction compared to previous results [13], with better improvements for signal models with higher multiplicities of low-momentum particles. No significant deviation from the background prediction is observed. The most stringent limits to date are obtained on the Higgs boson branching fraction to a SUEP. For the signal model studied in Ref. [12], we find an upper limit on this branching fraction of 0.0066. Model-agnostic fits are provided for the purpose of reinterpretation.

References
1	M. Cveti \v c , P. Langacker, and G. Shiu	Phenomenology of a three-family standardlike string model	PRD 66 (2002) 066004	hep-ph/0205252
2	Z. Chacko, H.-S. Goh, and R. Harnik	The twin Higgs: Natural electroweak breaking from mirror symmetry	PRL 96 (2006) 231802	hep-ph/0506256
3	M. J. Strassler and K. M. Zurek	Echoes of a hidden valley at hadron colliders	PLB 651 (2007) 374	hep-ph/0604261
4	T. Hur, D.-W. Jung, P. Ko, and J. Y. Lee	Electroweak symmetry breaking and cold dark matter from strongly interacting hidden sector	PLB 696 (2011) 262	0709.1218
5	S. A. Abel et al.	Kinetic mixing of the photon with hidden U(1)s in string phenomenology	JHEP 07 (2008) 124	0803.1449
6	Y. Bai and P. Schwaller	Scale of dark QCD	PRD 89 (2014) 063522	1306.4676
7	P. Schwaller, D. Stolarski, and A. Weiler	Emerging jets	JHEP 05 (2015) 059	1502.05409
8	T. Cohen, M. Lisanti, and H. K. Lou	Semivisible jets: Dark matter undercover at the LHC	PRL 115 (2015) 171804	1503.00009
9	J. Polchinski and M. J. Strassler	Deep inelastic scattering and gauge / string duality	JHEP 05 (2003) 012	hep-th/0209211
10	D. M. Hofman and J. Maldacena	Conformal collider physics: Energy and charge correlations	JHEP 05 (2008) 012	0803.1467
11	M. J. Strassler	Why unparticle models with mass gaps are examples of hidden valleys		0801.0629
12	S. Knapen, S. Pagan Griso, M. Papucci, and D. J. Robinson	Triggering soft bombs at the LHC	JHEP 08 (2017) 076	1612.00850
13	CMS Collaboration	Search for soft unclustered energy patterns in proton-proton collisions at 13 TeV	PRL 133 (2024) 191902	CMS-EXO-23-002 2403.05311
14	M. Buschmann, J. Kopp, J. Liu, and P. A. N. Machado	Lepton jets from radiating dark matter	JHEP 07 (2015) 045	1505.07459
15	M. Graham, C. Hearty, and M. Williams	Searches for dark photons at accelerators	Ann. Rev. Nucl. Part. Sci. 71 (2021) 37	2104.10280
16	T. Sjostrand et al.	An introduction to PYTHIA 8.2	Comput. Phys. Commun. 191 (2015) 159	1410.3012
17	J. Barron et al.	Unsupervised hadronic SUEP at the LHC	JHEP 12 (2021) 129	2107.12379
18	NNPDF Collaboration	Parton distributions from high-precision collider data	EPJC 77 (2017) 663	1706.00428
19	CMS Collaboration	Extraction and validation of a new set of CMS PYTHIA8 tunes from underlying-event measurements	EPJC 80 (2020) 4	CMS-GEN-17-001 1903.12179
20	GEANT4 Collaboration	GEANT 4---a simulation toolkit	NIM A 506 (2003) 250
21	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004
22	CMS Collaboration	Performance of the CMS Level-1 trigger in proton-proton collisions at $ \sqrt{s} = $ 13 TeV	JINST 15 (2020) P10017	CMS-TRG-17-001 2006.10165
23	CMS Collaboration	The CMS trigger system	JINST 12 (2017) P01020	CMS-TRG-12-001 1609.02366
24	CMS Collaboration	Performance of the CMS high-level trigger during LHC Run 2	JINST 19 (2024) P11021	CMS-TRG-19-001 2410.17038
25	CMS Collaboration	Electron and photon reconstruction and identification with the CMS experiment at the CERN LHC	JINST 16 (2021) P05014	CMS-EGM-17-001 2012.06888
26	CMS Collaboration	Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $ \sqrt{s}= $ 13 TeV	JINST 13 (2018) P06015	CMS-MUO-16-001 1804.04528
27	CMS Collaboration	Description and performance of track and primary-vertex reconstruction with the CMS tracker	JINST 9 (2014) P10009	CMS-TRK-11-001 1405.6569
28	CMS Collaboration	Particle-flow reconstruction and global event description with the CMS detector	JINST 12 (2017) P10003	CMS-PRF-14-001 1706.04965
29	CMS Collaboration	Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV	JINST 12 (2017) P02014	CMS-JME-13-004 1607.03663
30	CMS Collaboration	Performance of missing transverse momentum reconstruction in proton-proton collisions at $ \sqrt{s} = $ 13 TeV using the CMS detector	JINST 14 (2019) P07004	CMS-JME-17-001 1903.06078
31	CMS Collaboration	Technical proposal for the Phase-II upgrade of the Compact Muon Solenoid	CMS Technical Proposal CERN-LHCC-2015-010, CMS-TDR-15-02, 2015 CDS
32	M. Cacciari, G. P. Salam, and G. Soyez	The anti-$ k_{\mathrm{T}} $ jet clustering algorithm	JHEP 04 (2008) 063	0802.1189
33	M. Cacciari, G. P. Salam, and G. Soyez	FastJet user manual	EPJC 72 (2012) 1896	1111.6097
34	CMS Collaboration	Jet algorithms performance in 13 TeV data	CMS Physics Analysis Summary, 2017 CMS-PAS-JME-16-003	CMS-PAS-JME-16-003
35	CMS Collaboration	Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV	JINST 13 (2018) P05011	CMS-BTV-16-002 1712.07158
36	CMS Collaboration	Performance of the DeepJet b tagging algorithm using 41.9/fb of data from proton-proton collisions at 13 TeV with Phase 1 CMS detector	CMS Detector Performance Summary CMS-DP-2018-058, 2018 CDS
37	E. Bols et al.	Jet flavour classification using DeepJet	JINST 15 (2020) P12012	2008.10519
38	D. Bertolini, P. Harris, M. Low, and N. Tran	Pileup per particle identification	JHEP 10 (2014) 059	1407.6013
39	C. Cesarotti, M. Reece, and M. J. Strassler	The efficacy of event isotropy as an event shape observable	JHEP 07 (2021) 215	2011.06599
40	S. Choi and H. Oh	Improved extrapolation methods of data-driven background estimations in high energy physics	EPJC 81 (2021) 643	1906.10831
41	CMS Collaboration	Measurement of the primary Lund jet plane density in proton-proton collisions at $ \sqrt{s} = $ 13 TeV	JHEP 05 (2024) 116	CMS-SMP-22-007 2312.16343
42	CMS Collaboration	Measurement of the inelastic proton-proton cross section at $ \sqrt{s}= $ 13 TeV	JHEP 07 (2018) 161	CMS-FSQ-15-005 1802.02613
43	CMS Collaboration	Performance of the CMS muon trigger system in proton-proton collisions at $ \sqrt{s} = $ 13 tev	JINST 16 (2021) P07001	CMS-MUO-19-001 2102.04790
44	CMS Collaboration	Precision luminosity measurement in proton-proton collisions at $ \sqrt{s} = $ 13 TeV in 2015 and 2016 at CMS	EPJC 81 (2021) 800	CMS-LUM-17-003 2104.01927
45	CMS	CMS luminosity measurement for the 2017 data-taking period at $ \sqrt{s} = $ 13 TeV	\href http://cds.cern.ch/record/262 Collaboration,, CMS Physics Analysis Summary, 1960	CMS-PAS-LUM-17-004
46	CMS	CMS luminosity measurement for the 2018 data-taking period at $ \sqrt{s} = $ 13 TeV	\href http://cds.cern.ch/record/2676164 Collaboration,, CMS Physics Analysis Summary, 2019	CMS-PAS-LUM-18-002
47	CMS Collaboration	The CMS statistical analysis and combination tool: COMBINE	Comput. Softw. Big Sci. 8 (2024) 19	CMS-CAT-23-001 2404.06614
48	T. Junk	Confidence level computation for combining searches with small statistics	NIM A 434 (1999) 435	hep-ex/9902006
49	A. L. Read	Presentation of search results: The $ \text{CL}_\text{s} $ technique	JPG 28 (2002) 2693
50	J. Alwall et al.	The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations	JHEP 07 (2014) 079	1405.0301
51	R. Frederix and S. Frixione	Merging meets matching in MC@NLO	JHEP 12 (2012) 061	1209.6215
52	P. Nason	A new method for combining NLO QCD with shower Monte Carlo algorithms	JHEP 11 (2004) 040	hep-ph/0409146
53	S. Frixione, P. Nason, and C. Oleari	Matching NLO QCD computations with parton shower simulations: the POWHEG method	JHEP 11 (2007) 070	0709.2092
54	S. Alioli, P. Nason, C. Oleari, and E. Re	A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX	JHEP 06 (2010) 043	1002.2581
55	S. Alioli, S.-O. Moch, and P. Uwer	Hadronic top-quark pair-production with one jet and parton showering	JHEP 01 (2012) 137	1110.5251
56	P. Nason and G. Zanderighi	$ \mathrm{W}^+ \mathrm{W}^- $, WZ and ZZ production in the POWHEG -box-v2	EPJC 74 (2014) 2702	1311.1365