CMS-HIG-18-024

CMS-HIG-18-024 ; CERN-EP-2020-061
Search for a light pseudoscalar Higgs boson in the boosted $\mu\mu\tau\tau$ final state in proton-proton collisions at $\sqrt{s} =$ 13 TeV
CMS Collaboration
18 May 2020
JHEP 08 (2020) 139
Abstract: A search for a light pseudoscalar Higgs boson (a) decaying from the 125 GeV (or a heavier) scalar Higgs boson (H) is performed using the 2016 LHC proton-proton collision data at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb $^{-1}$ , collected by the CMS experiment. The analysis considers gluon fusion and vector boson fusion production of the H, followed by the decay $\mathrm{H}\to\mathrm{a}\mathrm{a}\to\mu\mu\tau\tau$ , and considers pseudoscalar masses in the range 3.6 $< {m_{\mathrm{a}}} <$ 21 GeV. Because of the large mass difference between the H and the a bosons and the small masses of the a boson decay products, both the $\mu\mu$ and the $\tau\tau$ pairs have high Lorentz boost and are collimated. The $\tau\tau$ reconstruction efficiency is increased by modifying the standard technique for hadronic $\tau$ lepton decay reconstruction to account for a nearby muon. No significant signal is observed. Model-independent limits are set at 95% confidence level, as a function of ${m_{\mathrm{a}}}$ , on the branching fraction ( ${\mathcal{B}}$ ) for $\mathrm{H}\to\mathrm{a}\mathrm{a}\to\mu\mu\tau\tau$ , down to 1.5 (2.0) $\times$ 10 $^{-4}$ for ${m_{\mathrm{H}}} =$ 125 (300) GeV. Model-dependent limits on ${\mathcal{B}}(\mathrm{H}\to\mathrm{a}\mathrm{a})$ are set within the context of two Higgs doublets plus singlet models, with the most stringent results obtained for Type-III models. These results extend current LHC searches for heavier a bosons that decay to resolved lepton pairs and provide the first such bounds for an H boson with a mass above 125 GeV.
Links: e-print arXiv:2005.08694 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: The efficiency of the standard HPS (dashed lines) and ${\tau _{\mu}} {\tau _{\mathrm{h}}}$ HPS reconstruction used in this search (solid lines) as a function of pseudoscalar boson mass for ${m_{\mathrm{H}}} =$ 125 (red) and 300 GeV (green). The events are required to have two reconstructed muons passing identification and isolation criteria. The efficiency is measured by additionally requiring a third muon passing identification requirements and a ${\tau _{\mathrm{h}}}$ candidate reconstructed using either the standard HPS algorithm or the ${\tau _{\mu}} {\tau _{\mathrm{h}}}$ HPS algorithm and passing isolation requirements.
png pdf	Figure 2: Schematic of the fit regions in the analysis. Events with two isolated muons and no ${\tau _{\mu}} {\tau _{\mathrm{h}}}$ candidates constitute the control region (blue). Events that have a ${\tau _{\mu}} {\tau _{\mathrm{h}}}$ candidate are further divided based on the isolation of the ${\tau _{\mathrm{h}}}$ candidate with isolated ${\tau _{\mu}} {\tau _{\mathrm{h}}}$ candidates forming the signal region (green) and the remaining ${\tau _{\mu}} {\tau _{\mathrm{h}}}$ candidates forming the sideband (red). Additionally, the $\mu \mu$ candidates that fail the muon isolation selection form two analogous regions for the validation of the background fit model (gray).
png pdf	Figure 3: Background model fits and observed data in the control region ${m(\mu \mu)}$ distribution. The figures are divided into three fit ranges: 2.5 $< {m(\mu \mu)} <$ 8.5 GeV (left), 6 $< {m(\mu \mu)} <$ 14 GeV (middle), and 11 $< {m(\mu \mu)} <$ 25 GeV (right).
png pdf	Figure 3-a: Background model fit and observed data in the control region ${m(\mu \mu)}$ distribution, in the fit range 2.5 $< {m(\mu \mu)} <$ 8.5 GeV.
png pdf	Figure 3-b: Background model fit and observed data in the control region ${m(\mu \mu)}$ distribution, in the fit range 6 $< {m(\mu \mu)} <$ 14 GeV.
png pdf	Figure 3-c: Background model fit and observed data in the control region ${m(\mu \mu)}$ distribution, in the fit range 11 $< {m(\mu \mu)} <$ 25 GeV.
png pdf	Figure 4: Projections of 2D background model fits and observed data in the sideband on the ${m(\mu \mu)}$ (left), and ${m(\mu \mu {\tau _{\mu}} {\tau _{\mathrm{h}}})}$ (right) axes with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV. The figures are divided into three fit ranges: 2.5 $< {m(\mu \mu)} <$ 8.5 GeV (upper), 6 $< {m(\mu \mu)} <$ 14 GeV (middle), and 11 $< {m(\mu \mu)} <$ 25 GeV (lower).
png pdf	Figure 4-a: Projection of the 2D background model fit and observed data in the sideband on the ${m(\mu \mu)}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV, in the fit range 2.5 $< {m(\mu \mu)} <$ 8.5 GeV.
png pdf	Figure 4-b: Projection of the 2D background model fit and observed data in the sideband on the ${m(\mu \mu {\tau _{\mu}} {\tau _{\mathrm{h}}})}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV, in the fit range 2.5 $< {m(\mu \mu)} <$ 8.5 GeV.
png pdf	Figure 4-c: Projection of the 2D background model fit and observed data in the sideband on the ${m(\mu \mu)}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV, in the fit range 6 $< {m(\mu \mu)} <$ 14 GeV.
png pdf	Figure 4-d: Projection of the 2D background model fit and observed data in the sideband on the ${m(\mu \mu {\tau _{\mu}} {\tau _{\mathrm{h}}})}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV, in the fit range 6 $< {m(\mu \mu)} <$ 14 GeV.
png pdf	Figure 4-e: Projection of the 2D background model fit and observed data in the sideband on the ${m(\mu \mu)}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV, in the fit range 11 $< {m(\mu \mu)} <$ 25 GeV.
png pdf	Figure 4-f: Projection of the 2D background model fit and observed data in the sideband on the ${m(\mu \mu {\tau _{\mu}} {\tau _{\mathrm{h}}})}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV, in the fit range 11 $< {m(\mu \mu)} <$ 25 GeV.
png pdf	Figure 5: Projections of 2D background model fits and observed data in the signal region on the ${m(\mu \mu)}$ (left), and ${m(\mu \mu {\tau _{\mu}} {\tau _{\mathrm{h}}})}$ (right) axes with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV. The figures are divided into three fit ranges: 2.5 $< {m(\mu \mu)} <$ 8.5 GeV (upper), 6 $< {m(\mu \mu)} <$ 14 GeV (middle), and 11 $< {m(\mu \mu)} <$ 25 GeV (lower).
png pdf	Figure 5-a: Projection of the 2D background model fit and observed data in the signal region on the ${m(\mu \mu)}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV in the fit range 2.5 $< {m(\mu \mu)} <$ 8.5 GeV.
png pdf	Figure 5-b: Projection of the 2D background model fit and observed data in the signal region on the ${m(\mu \mu {\tau _{\mu}} {\tau _{\mathrm{h}}})}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV in the fit range 2.5 $< {m(\mu \mu)} <$ 8.5 GeV.
png pdf	Figure 5-c: Projection of the 2D background model fit and observed data in the signal region on the ${m(\mu \mu)}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV in the fit range 6 $< {m(\mu \mu)} <$ 14 GeV.
png pdf	Figure 5-d: Projection of the 2D background model fit and observed data in the signal region on the ${m(\mu \mu {\tau _{\mu}} {\tau _{\mathrm{h}}})}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV in the fit range 6 $< {m(\mu \mu)} <$ 14 GeV.
png pdf	Figure 5-e: Projection of the 2D background model fit and observed data in the signal region on the ${m(\mu \mu)}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV in the fit range 11 $< {m(\mu \mu)} <$ 25 GeV.
png pdf	Figure 5-f: Projection of the 2D background model fit and observed data in the signal region on the ${m(\mu \mu {\tau _{\mu}} {\tau _{\mathrm{h}}})}$ axis with sample signal distributions that assume H boson masses of ${m_{\mathrm{H}}} =$ 125 and 300 GeV in the fit range 11 $< {m(\mu \mu)} <$ 25 GeV.
png pdf	Figure 6: Observed data distribution, as a function of the 4-body visible mass and $\mu \mu$ invariant mass for the signal region; 614 events are observed.
png pdf	Figure 7: Model-independent 95% CL upper limits on ${\sigma _{\mathrm{H}}} {\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a} \to \mu \mu \tau \tau)/ {\sigma _{\text {SM}}}$ as a function of pseudoscalar boson mass for a Higgs boson with ${m_{\mathrm{H}}} =$ 125 GeV (left), and 300 GeV (right). The vertical dashed lines indicate the transition between the $\mu \mu$ mass fit ranges for a given mass hypothesis, occurring at ${m_{\mathrm{a}}} =$ 8 and 11.5 GeV. The inner (green) band and the outer (yellow) band indicate the regions containing 68 and 95%, respectively, of the distribution of limits expected under the background-only hypothesis.
png pdf	Figure 7-a: Model-independent 95% CL upper limits on ${\sigma _{\mathrm{H}}} {\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a} \to \mu \mu \tau \tau)/ {\sigma _{\text {SM}}}$ as a function of pseudoscalar boson mass for a Higgs boson with ${m_{\mathrm{H}}} =$ 125 GeV. The vertical dashed lines indicate the transition between the $\mu \mu$ mass fit ranges for a given mass hypothesis, occurring at ${m_{\mathrm{a}}} =$ 8 and 11.5 GeV. The inner (green) band and the outer (yellow) band indicate the regions containing 68 and 95%, respectively, of the distribution of limits expected under the background-only hypothesis.
png pdf	Figure 7-b: Model-independent 95% CL upper limits on ${\sigma _{\mathrm{H}}} {\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a} \to \mu \mu \tau \tau)/ {\sigma _{\text {SM}}}$ as a function of pseudoscalar boson mass for a Higgs boson with ${m_{\mathrm{H}}} =$ 300 GeV. The vertical dashed lines indicate the transition between the $\mu \mu$ mass fit ranges for a given mass hypothesis, occurring at ${m_{\mathrm{a}}} =$ 8 and 11.5 GeV. The inner (green) band and the outer (yellow) band indicate the regions containing 68 and 95%, respectively, of the distribution of limits expected under the background-only hypothesis.
png pdf	Figure 8: Observed (black) and expected (blue, median and 68%) model-specific 95% CL upper limits on ${\sigma _{\mathrm{H}}} {\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})/ {\sigma _{\text {SM}}}$ as a function of ${m_{\mathrm{a}}}$ for the Type-I 2HDM+S at ${\tan\beta} =$ 1.5 and ${m_{\mathrm{H}}} =$ 125 GeV. The assumed model branching fractions for pseudoscalar Higgs boson decay to $\mu \mu$ and $\tau \tau$ are taken from Ref. [71] and are approximately independent of ${\tan\beta}$ .
png pdf	Figure 9: Model-specific 95% CL upper limits on ${\sigma _{\mathrm{H}}} {\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})/ {\sigma _{\text {SM}}}$ for three model types of the 2HDM+S as a function of ${\tan\beta}$ and ${m_{\mathrm{a}}}$ , for ${m_{\mathrm{H}}} =$ 125 GeV. Contours for two values of ${\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})$ are shown for reference. The assumed model branching fractions for pseudoscalar Higgs boson decay to $\mu \mu$ and $\tau \tau$ are taken from Ref. [71].
png pdf	Figure 9-a: Model-specific 95% CL upper limits on ${\sigma _{\mathrm{H}}} {\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})/ {\sigma _{\text {SM}}}$ for model 2HDM+S Type II as a function of ${\tan\beta}$ and ${m_{\mathrm{a}}}$ , for ${m_{\mathrm{H}}} =$ 125 GeV. Contours for two values of ${\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})$ are shown for reference. The assumed model branching fractions for pseudoscalar Higgs boson decay to $\mu \mu$ and $\tau \tau$ are taken from Ref. [71].
png pdf	Figure 9-b: Model-specific 95% CL upper limits on ${\sigma _{\mathrm{H}}} {\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})/ {\sigma _{\text {SM}}}$ for model 2HDM+S Type III as a function of ${\tan\beta}$ and ${m_{\mathrm{a}}}$ , for ${m_{\mathrm{H}}} =$ 125 GeV. Contours for two values of ${\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})$ are shown for reference. The assumed model branching fractions for pseudoscalar Higgs boson decay to $\mu \mu$ and $\tau \tau$ are taken from Ref. [71].
png pdf	Figure 9-c: Model-specific 95% CL upper limits on ${\sigma _{\mathrm{H}}} {\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})/ {\sigma _{\text {SM}}}$ for model 2HDM+S Type IV as a function of ${\tan\beta}$ and ${m_{\mathrm{a}}}$ , for ${m_{\mathrm{H}}} =$ 125 GeV. Contours for two values of ${\mathcal {B}}(\mathrm{H} \to \mathrm{a} \mathrm{a})$ are shown for reference. The assumed model branching fractions for pseudoscalar Higgs boson decay to $\mu \mu$ and $\tau \tau$ are taken from Ref. [71].

Tables

png pdf

Table 1:
Background model parameters and their relations among the three fit regions in the analysis. The

${\mu \mu}$ background model includes the five meson resonances modeled using a Voigt function over an exponential continuum. The 4-body background model includes an error function multiplied with the sum of two exponential distributions. Three types of fit region relations are used: (a) constrained, in which the parameters are the same in the indicated regions, (b) free, in which the parameter is not related to those in any other region, and (c) related via the

${\tau _{\mu}} {\tau _{\mathrm{h}}}$ tight-to-loose ratio, in which the indicated parameter in the signal region is constrained to the corresponding parameter in the sideband via a linear transformation.

Summary

A search for Higgs boson (H) decays to a pair of light pseudoscalar bosons (a) is presented, including the first such LHC results for an H with mass above 125 GeV. The light pseudoscalars decay to

$\mu\mu$ and

$\tau\tau$ with substantial overlap between the leptons because of the Lorentz boost. This difficult topology motivates the development of a dedicated

$\tau_{\mu}\tau_{\mathrm{h}}$ reconstruction method to increase the acceptance. Data collected by the CMS Collaboration at

$\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb

$^{-1}$ , are examined and no significant excess over standard model (SM) processes is observed. This analysis obtains model-independent upper limits at 95% confidence level on the branching fraction (

${\mathcal{B}}$ ) of a SM-like Higgs boson (H), decaying to a pair of pseudoscalar bosons (a) in the

$\mu\mu\tau\tau$ final state,

${\sigma_{\mathrm{H}}} {\mathcal{B}}(\mathrm{H}\to\mathrm{a}\mathrm{a}\to\mu\mu\tau\tau)/{\sigma_{\text{SM}}}$ , as well as model-specific upper limits on

${\sigma_{\mathrm{H}}} {\mathcal{B}}(\mathrm{H}\to\mathrm{a}\mathrm{a})/{\sigma_{\text{SM}}}$ for Type-I, -II, -III, and -IV two Higgs doublets plus singlet models. In the Type-I model, the upper limit on the allowed branching fraction is approximately independent of

${\tan\beta}$ , with the most stringent limit of 5% set for

${m_{\mathrm{a}}} \approx$ 4.5 GeV. For the Type-II and -III models with

${m_{\mathrm{a}}}$ below the

$\mathrm{b\bar{b}}$ threshold, upper limits on

${\mathcal{B}}(\mathrm{H}\to\mathrm{a}\mathrm{a})$ are stronger than the 0.47 inferred from combined measurements of SM Higgs couplings for

${\tan\beta}\gtrsim$ 0.8-0.9, becoming as strong as 10% for

${\tan\beta}\gtrsim$ 1.5. In the Type-III models, the predicted branching fraction to leptons increases with

${\tan\beta}$ , leading to strong upper limits for all pseudoscalar boson masses tested when

${\tan\beta}\gtrsim$ 1.5. In contrast, the strongest upper limits for Type-IV models are set when

${\tan\beta} <$ 1. These results significantly extend upper limits obtained by earlier searches by the CMS and ATLAS Collaborations, such as those obtained by CMS with 8 TeV data [39], and are complementary to present searches (e.g. Ref. [40]) at higher

${m_{\mathrm{a}}}$ that lead to resolved

$\mu\mu$ and

$\tau\tau$ final states.

References
1	ATLAS Collaboration	Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC	PLB 726 (2013) 88	1307.1427
2	ATLAS and CMS Collaborations	Measurements of the Higgs boson production and decay rates and constraints on its couplings from a combined ATLAS and CMS analysis of the LHC pp collision data at $\sqrt{s}=$ 7 and 8 TeV	JHEP 08 (2016) 045	1606.02266
3	CMS Collaboration	Measurements of properties of the Higgs boson decaying into the four-lepton final state in pp collisions at $\sqrt{s}=$ 13 TeV	JHEP 11 (2017) 047	CMS-HIG-16-041 1706.09936
4	ATLAS Collaboration	Measurement of the Higgs boson mass from the $H\rightarrow \gamma\gamma$ and $H \rightarrow ZZ^{*} \rightarrow 4\ell$ channels with the ATLAS detector using 25 fb $^{-1}$ of pp collision data	PRD 90 (2014) 052004	1406.3827
5	ATLAS and CMS Collaborations	Combined measurement of the Higgs boson mass in pp collisions at $\sqrt{s}=$ 7 and 8 TeV with the ATLAS and CMS experiments	PRL 114 (2015) 191803	1503.07589
6	G. C. Branco et al.	Theory and phenomenology of two-Higgs-doublet models	PR 516 (2012) 1	1106.0034
7	D. Curtin et al.	Exotic decays of the 125 GeV Higgs boson	PRD 90 (2014) 075004	1312.4992
8	U. Ellwanger, C. Hugonie, and A. M. Teixeira	The next-to-minimal supersymmetric standard model	PR 496 (2010) 1	0910.1785
9	CMS Collaboration	Combined measurements of Higgs boson couplings in proton-proton collisions at $\sqrt{s}=$ 13 TeV	EPJC 79 (2019) 421	CMS-HIG-17-031 1809.10733
10	R. Dermisek and J. F. Gunion	Escaping the large fine tuning and little hierarchy problems in the next to minimal supersymmetric model and $h\rightarrow aa$ decays	PRL 95 (2005) 041801	hep-ph/0502105
11	R. Dermisek and J. F. Gunion	The NMSSM close to the R-symmetry limit and naturalness in $h\rightarrow aa$ decays for $m(a) < 2m(b)$	PRD 75 (2007) 075019	hep-ph/0611142
12	S. Chang, R. Dermisek, J. F. Gunion, and N. Weiner	Nonstandard Higgs boson decays	Ann. Rev. Nucl. Part. Sci. 58 (2008) 75	0801.4554
13	J. F. Gunion, H. E. Haber, G. L. Kane, and S. Dawson	The Higgs Hunter's Guide	volume 80 of Frontiers in Physics Perseus Books
14	S. F. King, M. Muhlleitner, R. Nevzorov, and K. Walz	Natural NMSSM Higgs bosons	NPB 870 (2013) 323	1211.5074
15	A. Celis, V. Ilisie, and A. Pich	LHC constraints on two-Higgs doublet models	JHEP 07 (2013) 053	1302.4022
16	B. Grinstein and P. Uttayarat	Carving out parameter space in Type-II two Higgs doublets model	JHEP 06 (2013) 094	1304.0028
17	B. Coleppa, F. Kling, and S. Su	Constraining Type II 2HDM in light of LHC Higgs searches	JHEP 01 (2014) 161	1305.0002
18	C.-Y. Chen, S. Dawson, and M. Sher	Heavy Higgs searches and constraints on two Higgs doublet models	PRD 88 (2013) 015018	1305.1624
19	N. Craig, J. Galloway, and S. Thomas	Searching for signs of the second Higgs doublet		1305.2424
20	L. Wang and X.-F. Han	Status of the aligned two-Higgs-doublet model confronted with the Higgs data	JHEP 04 (2014) 128	1312.4759
21	J. Cao et al.	A light Higgs scalar in the NMSSM confronted with the latest LHC Higgs data	JHEP 11 (2013) 018	1309.4939
22	N. D. Christensen, T. Han, Z. Liu, and S. Su	Low-mass Higgs bosons in the NMSSM and their LHC implications	JHEP 08 (2013) 019	1303.2113
23	D. G. Cerdeno, P. Ghosh, and C. B. Park	Probing the two light Higgs scenario in the NMSSM with a low-mass pseudoscalar	JHEP 06 (2013) 031	1301.1325
24	G. Chalons and F. Domingo	Analysis of the Higgs potentials for two doublets and a singlet	PRD 86 (2012) 115024	1209.6235
25	A. Ahriche, A. Arhrib, and S. Nasri	Higgs phenomenology in the two-singlet model	JHEP 02 (2014) 042	1309.5615
26	J. Baglio, O. Eberhardt, U. Nierste, and M. Wiebusch	Benchmarks for Higgs pair production and heavy Higgs boson searches in the two-Higgs-doublet model of Type II	PRD 90 (2014) 015008	1403.1264
27	B. Dumont, J. F. Gunion, Y. Jiang, and S. Kraml	Constraints on and future prospects for two-Higgs-doublet models in light of the LHC Higgs signal	PRD 90 (2014) 035021	1405.3584
28	J. Bernon et al.	Scrutinizing the alignment limit in two-Higgs-doublet models: m $_h =$ 125 GeV	PRD 92 (2015) 075004	1507.00933
29	ALEPH Collaboration	Search for a nonminimal Higgs boson produced in the reaction $e^{+} e^{-} \to \mathrm{h} {Z}^{*}$	PLB 313 (1993) 312
30	L3 Collaboration	Search for neutral Higgs boson production through the process $e^{+} e^{-} \to {Z}^{*} \mathrm{H}^{0}$	PLB 385 (1996) 454
31	OPAL Collaboration	Decay mode independent searches for new scalar bosons with the OPAL detector at LEP	EPJC 27 (2003) 311	hep-ex/0206022
32	S. F. King, M. Muhlleitner, R. Nevzorov, and K. Walz	Discovery prospects for NMSSM Higgs bosons at the high-energy large hadron collider	PRD 90 (2014) 095014	1408.1120
33	ALEPH Collaboration	Search for neutral Higgs bosons decaying into four taus at LEP2	JHEP 05 (2010) 049	1003.0705
34	CMS Collaboration	Search for a light pseudoscalar Higgs boson in the dimuon decay channel in pp collisions at $\sqrt{s}=$ 7 TeV	PRL 109 (2012) 121801	CMS-HIG-12-004 1206.6326
35	R. Dermisek and J. F. Gunion	Direct production of a light CP-odd Higgs boson at the Tevatron and LHC	PRD 81 (2010) 055001	0911.2460
36	LHCb Collaboration	Search for a dimuon resonance in the $\upsilon$ mass region	JHEP 09 (2018) 147	1805.09820
37	CMS Collaboration	A search for pair production of new light bosons decaying into muons in proton-proton collisions at 13 TeV	PLB 796 (2019) 131	CMS-HIG-18-003 1812.00380
38	ATLAS Collaboration	Search for Higgs boson decays to beyond-the-standard-model light bosons in four-lepton events with the ATLAS detector at $\sqrt{s}=$ 13 TeV	JHEP 06 (2018) 166	1802.03388
39	CMS Collaboration	Search for light bosons in decays of the 125 GeV Higgs boson in proton-proton collisions at $\sqrt{s}=$ 8 TeV	JHEP 10 (2017) 076	CMS-HIG-16-015 1701.02032
40	CMS Collaboration	Search for an exotic decay of the Higgs boson to a pair of light pseudoscalars in the final state of two muons and two $\tau$ leptons in proton-proton collisions at $\sqrt{s}=$ 13 TeV	JHEP 11 (2018) 018	CMS-HIG-17-029 1805.04865
41	CMS Collaboration	Search for an exotic decay of the Higgs boson to a pair of light pseudoscalars in the final state with two b quarks and two $\tau$ leptons in proton-proton collisions at $\sqrt{s}=$ 13 TeV	PLB 785 (2018) 462	CMS-HIG-17-024 1805.10191
42	CMS Collaboration	Search for light pseudoscalar boson pairs produced from decays of the 125 GeV Higgs boson in final states with two muons and two nearby tracks in pp collisions at $\sqrt{s}=$ 13 TeV	PLB 800 (2020) 135087	CMS-HIG-18-006 1907.07235
43	ATLAS Collaboration	Search for Higgs bosons decaying to $aa$ in the $\mu\mu\tau\tau$ final state in pp collisions at $\sqrt{s} =$ 8 TeV with the ATLAS experiment	PRD 92 (2015) 052002	1505.01609
44	ATLAS Collaboration	Search for Higgs boson decays into a pair of light bosons in the $bb\mu\mu$ final state in pp collision at $\sqrt{s} =$ 13 TeV with the ATLAS detector	PLB 790 (2019) 1	1807.00539
45	ATLAS Collaboration	Search for the Higgs boson produced in association with a vector boson and decaying into two spin-zero particles in the $h \rightarrow aa \rightarrow 4b$ channel in pp collisions at $\sqrt{s} =$ 13 TeV with the ATLAS detector	JHEP 10 (2018) 031	1806.07355
46	LHC Higgs Cross Section Working Group	Handbook of LHC Higgs cross sections: 4. deciphering the nature of the Higgs sector	CERN (2016)	1610.07922
47	J. Bernon, J. F. Gunion, Y. Jiang, and S. Kraml	Light Higgs bosons in two-Higgs-doublet models	PRD 91 (2015) 075019	1412.3385
48	CMS Collaboration	The CMS trigger system	JINST 12 (2017) P01020	CMS-TRG-12-001 1609.02366
49	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
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	T. Sjostrand et al.	An introduction to PYTHIA 8.2	CPC 191 (2015) 159	1410.3012
52	CMS Collaboration	Event generator tunes obtained from underlying event and multiparton scattering measurements	EPJC 76 (2016) 155	CMS-GEN-14-001 1512.00815
53	NNPDF Collaboration	Parton distributions from high-precision collider data	EPJC 77 (2017) 663	1706.00428
54	GEANT4 Collaboration	GEANT4--a simulation toolkit	NIMA 506 (2003) 250
55	CMS Collaboration	Particle-flow reconstruction and global event description with the CMS detector	JINST 12 (2017) P10003	CMS-PRF-14-001 1706.04965
56	M. Cacciari, G. P. Salam, and G. Soyez	The anti- ${k_{\mathrm{T}}}$ jet clustering algorithm	JHEP 04 (2008) 063	0802.1189
57	M. Cacciari, G. P. Salam, and G. Soyez	FastJet user manual	EPJC 72 (2012) 1896	1111.6097
58	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
59	CMS Collaboration	Determination of jet energy calibration and transverse momentum resolution in CMS	JINST 6 (2011) P11002	CMS-JME-10-011 1107.4277
60	CMS Collaboration	Pileup mitigation at CMS in 13 TeV data	CMS-PAS-JME-18-001	CMS-PAS-JME-18-001
61	CMS Collaboration	Identification of b quark jets with the CMS experiment	JINST 8 (2013) P04013	CMS-BTV-12-001 1211.4462
62	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
63	CMS Collaboration	Performance of reconstruction and identification of $\tau$ leptons decaying to hadrons and $\nu_\tau$ in pp collisions at $\sqrt{s}=$ 13 TeV	JINST 13 (2018) P10005	CMS-TAU-16-003 1809.02816
64	CMS Collaboration	Measurement of the inclusive $\mathrm{W}$ and $\mathrm{Z}$ production cross sections in pp collisions at $\sqrt{s}=$ 7 TeV with the CMS experiment	JHEP 10 (2011) 132	CMS-EWK-10-005 1107.4789
65	Particle Data Group, M. Tanabashi et al.	Review of particle physics	PRD 98 (2018) 030001
66	CMS Collaboration	CMS luminosity measurements for the 2016 data taking period	CMS-PAS-LUM-17-001	CMS-PAS-LUM-17-001
67	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
68	T. Junk	Confidence level computation for combining searches with small statistics	NIMA 434 (1999) 435	hep-ex/9902006
69	A. L. Read	Presentation of search results: The CL $_{\rm{s}}$ technique	JPG 28 (2002) 2693
70	ATLAS and CMS Collaborations, and The LHC Higgs Combination Group	Procedure for the LHC Higgs boson search combination in Summer 2011	CMS-NOTE-2011-005
71	U. Haisch, J. F. Kamenik, A. Malinauskas, and M. Spira	Collider constraints on light pseudoscalars	JHEP 03 (2018) 178	1802.02156