https://doi.org/10.1140/epjc/s10052-024-12727-4
Regular Article - Experimental Physics
Search for exotic decays of the Higgs boson to a pair of pseudoscalars in the 
and 
final states
1
Yerevan Physics Institute, Yerevan, Armenia
2
Institut für Hochenergiephysik, Vienna, Austria
3
Universiteit Antwerpen, Antwerp, Belgium
4
Vrije Universiteit Brussel, Brussels, Belgium
5
Université Libre de Bruxelles, Brussels, Belgium
6
Ghent University, Ghent, Belgium
7
Université Catholique de Louvain, Louvain-la-Neuve, Belgium
8
Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil
9
Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
10
Universidade Estadual Paulista, Universidade Federal do ABC, São Paulo, Brazil
11
Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria
12
University of Sofia, Sofia, Bulgaria
13
Instituto De Alta Investigación, Universidad de Tarapacá, Casilla 7 D, Arica, Chile
14
Beihang University, Beijing, China
15
Department of Physics, Tsinghua University, Beijing, China
16
Institute of High Energy Physics, Beijing, China
17
State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
18
Sun Yat-Sen University, Guangzhou, China
19
University of Science and Technology of China, Hefei, China
20
Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)-Fudan University, Shanghai, China
21
Zhejiang University, Hangzhou, Zhejiang, China
22
Universidad de Los Andes, Bogotá, Colombia
23
Universidad de Antioquia, Medellín, Colombia
24
Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, Split, Croatia
25
Faculty of Science, University of Split, Split, Croatia
26
Institute Rudjer Boskovic, Zagreb, Croatia
27
University of Cyprus, Nicosia, Cyprus
28
Charles University, Prague, Czech Republic
29
Escuela Politecnica Nacional, Quito, Ecuador
30
Universidad San Francisco de Quito, Quito, Ecuador
31
Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt
32
Center for High Energy Physics (CHEP-FU), Fayoum University, El-Fayoum, Egypt
33
National Institute of Chemical Physics and Biophysics, Tallinn, Estonia
34
Department of Physics, University of Helsinki, Helsinki, Finland
35
Helsinki Institute of Physics, Helsinki, Finland
36
Lappeenranta-Lahti University of Technology, Lappeenranta, Finland
37
IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France
38
Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France
39
Université de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg, France
40
Institut de Physique des 2 Infinis de Lyon (IP2I), Villeurbanne, France
41
Georgian Technical University, Tbilisi, Georgia
42
I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany
43
III. Physikalisches Institut A, RWTH Aachen University, Aachen, Germany
44
III. Physikalisches Institut B, RWTH Aachen University, Aachen, Germany
45
Deutsches Elektronen-Synchrotron, Hamburg, Germany
46
University of Hamburg, Hamburg, Germany
47
Karlsruher Institut fuer Technologie, Karlsruhe, Germany
48
Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Agia Paraskevi, Greece
49
National and Kapodistrian University of Athens, Athens, Greece
50
National Technical University of Athens, Athens, Greece
51
University of Ioánnina, Ioannina, Greece
52
HUN-REN Wigner Research Centre for Physics, Budapest, Hungary
53
MTA-ELTE Lendület CMS Particle and Nuclear Physics Group, Eötvös Loránd University, Budapest, Hungary
54
Faculty of Informatics, University of Debrecen, Debrecen, Hungary
55
Institute of Nuclear Research ATOMKI, Debrecen, Hungary
56
MATE Institute of Technology, Karoly Robert Campus, Gyongyos, Hungary
57
Panjab University, Chandigarh, India
58
University of Delhi, Delhi, India
59
Saha Institute of Nuclear Physics, HBNI, Kolkata, India
60
Indian Institute of Technology Madras, Chennai, India
61
Tata Institute of Fundamental Research-A, Mumbai, India
62
Tata Institute of Fundamental Research-B, Mumbai, India
63
National Institute of Science Education and Research, An OCC of Homi Bhabha National Institute, Bhubaneswar, Odisha, India
64
Indian Institute of Science Education and Research (IISER), Pune, India
65
Isfahan University of Technology, Isfahan, Iran
66
Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
67
University College Dublin, Dublin, Ireland
68
INFN Sezione di Bari, Università di Bari, Politecnico di Bari, Bari, Italy
69
INFN Sezione di Bologna, Università di Bologna, Bologna, Italy
70
INFN Sezione di Catania, Università di Catania, Catania, Italy
71
INFN Sezione di Firenze, Università di Firenze, Florence, Italy
72
INFN Laboratori Nazionali di Frascati, Frascati, Italy
73
INFN Sezione di Genova, Università di Genova, Genoa, Italy
74
INFN Sezione di Milano-Bicocca, Università di Milano-Bicocca, Milan, Italy
75
INFN Sezione di Napoli, Università di Napoli ‘Federico II’, Naples, Italy; Università della Basilicata, Potenza, Italy; Scuola Superiore Meridionale (SSM), Naples, Italy
76
INFN Sezione di Padova, Università di Padova, Padua, Italy; Università di Trento, Trento, Italy
77
INFN Sezione di Pavia, Università di Pavia, Pavia, Italy
78
INFN Sezione di Perugia, Università di Perugia, Perugia, Italy
79
INFN Sezione di Pisa, Università di Pisa, Scuola Normale Superiore di Pisa, Pisa, Italy; Università di Siena, Siena, Italy
80
INFN Sezione di Roma, Sapienza Università di Roma, Rome, Italy
81
INFN Sezione di Torino, Università di Torino, Turin, Italy; Università del Piemonte Orientale, Novara, Italy
82
INFN Sezione di Trieste, Università di Trieste, Trieste, Italy
83
Kyungpook National University, Daegu, Korea
84
Institute for Universe and Elementary Particles, Chonnam National University, Kwangju, Korea
85
Hanyang University, Seoul, Korea
86
Korea University, Seoul, Korea
87
Department of Physics, Kyung Hee University, Seoul, Korea
88
Sejong University, Seoul, Korea
89
Seoul National University, Seoul, Korea
90
University of Seoul, Seoul, Korea
91
Department of Physics, Yonsei University, Seoul, Korea
92
Sungkyunkwan University, Suwon, Korea
93
College of Engineering and Technology, American University of the Middle East (AUM), Dasman, Kuwait
94
Riga Technical University, Riga, Latvia
95
University of Latvia (LU), Riga, Latvia
96
Vilnius University, Vilnius, Lithuania
97
National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia
98
Universidad de Sonora (UNISON), Hermosillo, Mexico
99
Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico
100
Universidad Iberoamericana, Mexico City, Mexico
101
Benemerita Universidad Autonoma de Puebla, Puebla, Mexico
102
University of Montenegro, Podgorica, Montenegro
103
University of Canterbury, Christchurch, New Zealand
104
National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan
105
Faculty of Computer Science, Electronics and Telecommunications, AGH University of Krakow, Kraków, Poland
106
National Centre for Nuclear Research, Swierk, Poland
107
Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
108
Warsaw University of Technology, Warsaw, Poland
109
Laboratório de Instrumentação e Física Experimental de Partículas, Lisbon, Portugal
110
Faculty of Physics, University of Belgrade, Belgrade, Serbia
111
VINCA Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
112
Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
113
Universidad Autónoma de Madrid, Madrid, Spain
114
Instituto Universitario de Ciencias y Tecnologías Espaciales de Asturias (ICTEA), Universidad de Oviedo, Oviedo, Spain
115
Instituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain
116
University of Colombo, Colombo, Sri Lanka
117
Department of Physics, University of Ruhuna, Matara, Sri Lanka
118
CERN, European Organization for Nuclear Research, Geneva, Switzerland
119
Paul Scherrer Institut, Villigen, Switzerland
120
ETH Zurich-Institute for Particle Physics and Astrophysics (IPA), Zurich, Switzerland
121
Universität Zürich, Zurich, Switzerland
122
National Central University, Chung-Li, Taiwan
123
National Taiwan University (NTU), Taipei, Taiwan
124
High Energy Physics Research Unit, Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
125
Physics Department, Science and Art Faculty, Çukurova University, Adana, Turkey
126
Physics Department, Middle East Technical University, Ankara, Turkey
127
Bogazici University, Istanbul, Turkey
128
Istanbul Technical University, Istanbul, Turkey
129
Istanbul University, Istanbul, Turkey
130
Institute for Scintillation Materials of National Academy of Science of Ukraine, Kharkiv, Ukraine
131
National Science Centre, Kharkiv Institute of Physics and Technology, Kharkiv, Ukraine
132
University of Bristol, Bristol, UK
133
Rutherford Appleton Laboratory, Didcot, UK
134
Imperial College, London, UK
135
Brunel University, Uxbridge, UK
136
Baylor University, Waco, TX, USA
137
Catholic University of America, Washington, DC, USA
138
The University of Alabama, Tuscaloosa, AL, USA
139
Boston University, Boston, MA, USA
140
Brown University, Providence, RI, USA
141
University of California, Davis, Davis, CA, USA
142
University of California, Los Angeles, CA, USA
143
University of California, Riverside, Riverside, CA, USA
144
University of California, San Diego, La Jolla, CA, USA
145
Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA
146
California Institute of Technology, Pasadena, CA, USA
147
Carnegie Mellon University, Pittsburgh, PA, USA
148
University of Colorado Boulder, Boulder, CO, USA
149
Cornell University, Ithaca, NY, USA
150
Fermi National Accelerator Laboratory, Batavia, IL, USA
151
University of Florida, Gainesville, FL, USA
152
Florida State University, Tallahassee, FL, USA
153
Florida Institute of Technology, Melbourne, FL, USA
154
University of Illinois Chicago, Chicago, USA
155
The University of Iowa, Iowa City, IA, USA
156
Johns Hopkins University, Baltimore, MD, USA
157
The University of Kansas, Lawrence, KS, USA
158
Kansas State University, Manhattan, KS, USA
159
Lawrence Livermore National Laboratory, Livermore, CA, USA
160
University of Maryland, College Park, MD, USA
161
Massachusetts Institute of Technology, Cambridge, MA, USA
162
University of Minnesota, Minneapolis, MN, USA
163
University of Mississippi, Oxford, MS, USA
164
University of Nebraska-Lincoln, Lincoln, NE, USA
165
State University of New York at Buffalo, Buffalo, NY, USA
166
Northeastern University, Boston, MA, USA
167
Northwestern University, Evanston, IL, USA
168
University of Notre Dame, Notre Dame, IN, USA
169
The Ohio State University, Columbus, OH, USA
170
Princeton University, Princeton, NJ, USA
171
University of Puerto Rico, Mayagüez, PR, USA
172
Purdue University, West Lafayette, IN, USA
173
Purdue University Northwest, Hammond, IN, USA
174
Rice University, Houston, TX, USA
175
University of Rochester, Rochester, NY, USA
176
The Rockefeller University, New York, NY, USA
177
Rutgers, The State University of New Jersey, Piscataway, NJ, USA
178
University of Tennessee, Knoxville, TN, USA
179
Texas A &M University, College Station, TX, USA
180
Texas Tech University, Lubbock, TX, USA
181
Vanderbilt University, Nashville, TN, USA
182
University of Virginia, Charlottesville, VA, USA
183
Wayne State University, Detroit, MI, USA
184
University of Wisconsin-Madison, Madison, WI, USA
185
Authors Affiliated with an Institute or an International Laboratory Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
186
Yerevan State University, Yerevan, Armenia
187
TU Wien, Vienna, Austria
188
Institute of Basic and Applied Sciences, Faculty of Engineering, Arab Academy for Science, Technology and Maritime Transport, Alexandria, Egypt
189
Ghent University, Ghent, Belgium
190
Universidade Estadual de Campinas, Campinas, Brazil
191
Federal University of Rio Grande do Sul, Porto Alegre, Brazil
192
UFMS, Nova Andradina, Brazil
193
Nanjing Normal University, Nanjing, China
194
Henan Normal University, Xinxiang, China
195
The University of Iowa, Iowa City, IA, USA
196
University of Chinese Academy of Sciences, Beijing, China
197
China Center of Advanced Science and Technology, Beijing, China
198
University of Chinese Academy of Sciences, Beijing, China
199
China Spallation Neutron Source, Dongguan, Guangdong, China
200
Université Libre de Bruxelles, Brussels, Belgium
201
an Institute or an International Laboratory Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
202
British University in Egypt, Cairo, Egypt
203
Cairo University, Cairo, Egypt
204
Birla Institute of Technology, Mesra, Mesra, India
205
Purdue University, West Lafayette, IN, USA
206
Université de Haute Alsace, Mulhouse, France
207
Department of Physics, Tsinghua University, Beijing, China
208
The University of the State of Amazonas, Manaus, Brazil
209
Erzincan Binali Yildirim University, Erzincan, Turkey
210
University of Hamburg, Hamburg, Germany
211
III. Physikalisches Institut A, RWTH Aachen University, Aachen, Germany
212
Isfahan University of Technology, Isfahan, Iran
213
Bergische University Wuppertal (BUW), Wuppertal, Germany
214
Brandenburg University of Technology, Cottbus, Germany
215
Forschungszentrum Jülich, Jülich, Germany
216
CERN, European Organization for Nuclear Research, Geneva, Switzerland
217
Institute of Physics, University of Debrecen, Debrecen, Hungary
218
Institute of Nuclear Research ATOMKI, Debrecen, Hungary
219
Universitatea Babes-Bolyai-Facultatea de Fizica, Cluj-Napoca, Romania
220
Physics Department, Faculty of Science, Assiut University, Asyût, Egypt
221
HUN-REN Wigner Research Centre for Physics, Budapest, Hungary
222
Faculty of Informatics, University of Debrecen, Debrecen, Hungary
223
Punjab Agricultural University, Ludhiana, India
224
University of Hyderabad, Hyderabad, India
225
University of Visva-Bharati, Santiniketan, India
226
Indian Institute of Science (IISc), Bangalore, India
227
IIT Bhubaneswar, Bhubaneswar, India
228
Institute of Physics, Bhubaneswar, India
229
Department of Physics, Isfahan University of Technology, Isfahan, Iran
230
Sharif University of Technology, Tehran, Iran
231
Department of Physics, University of Science and Technology of Mazandaran, Behshahr, Iran
232
Helwan University, Cairo, Egypt
233
Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Bologna, Italy
234
Centro Siciliano di Fisica Nucleare e di Struttura Della Materia, Catania, Italy
235
Università degli Studi Guglielmo Marconi, Rome, Italy
236
Scuola Superiore Meridionale, Università di Napoli ‘Federico II’, Naples, Italy
237
Fermi National Accelerator Laboratory, Batavia, IL, USA
238
Università di Napoli ‘Federico II’, Naples, Italy
239
Ain Shams University, Cairo, Egypt
240
Consiglio Nazionale delle Ricerche-Istituto Officina dei Materiali, Perugia, Italy
241
Riga Technical University, Riga, Latvia
242
Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia
243
Consejo Nacional de Ciencia y Tecnología, Mexico City, Mexico
244
Trincomalee Campus, Eastern University, Sri Lanka, Nilaveli, Sri Lanka
245
Saegis Campus, Nugegoda, Sri Lanka
246
INFN Sezione di Pavia, Università di Pavia, Pavia, Italy
247
National and Kapodistrian University of Athens, Athens, Greece
248
Ecole Polytechnique Fédérale Lausanne, Lausanne, Switzerland
249
University of Vienna Faculty of Computer Science, Vienna, Austria
250
Universität Zürich, Zurich, Switzerland
251
Stefan Meyer Institute for Subatomic Physics, Vienna, Austria
252
Laboratoire d’Annecy-le-Vieux de Physique des Particules, IN2P3-CNRS, Annecy-le-Vieux, France
253
Near East University, Research Center of Experimental Health Science, Mersin, Turkey
254
Konya Technical University, Konya, Turkey
255
Izmir Bakircay University, Izmir, Turkey
256
Adiyaman University, Adiyaman, Turkey
257
Bozok Universitesi Rektörlügü, Yozgat, Turkey
258
Marmara University, Istanbul, Turkey
259
Milli Savunma University, Istanbul, Turkey
260
Kafkas University, Kars, Turkey
261
Hacettepe University, Ankara, Turkey
262
Faculty of Engineering, Istanbul University-Cerrahpasa, Istanbul, Turkey
263
Yildiz Technical University, Istanbul, Turkey
264
Vrije Universiteit Brussel, Brussels, Belgium
265
School of Physics and Astronomy, University of Southampton, Southampton, UK
266
University of Bristol, Bristol, UK
267
IPPP Durham University, Durham, UK
268
Faculty of Science, Monash University, Clayton, Australia
269
an Institute or an International Laboratory Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
270
Università di Torino, Turin, Italy
271
Bethel University, St. Paul, MN, USA
272
Karamanoğlu Mehmetbey University, Karaman, Turkey
273
California Institute of Technology, Pasadena, CA, USA
274
United States Naval Academy, Annapolis, MD, USA
275
Bingol University, Bingol, Turkey
276
Georgian Technical University, Tbilisi, Georgia
277
Sinop University, Sinop, Turkey
278
Erciyes University, Kayseri, Turkey
279
Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), Bucharest, Romania
280
Texas A &M University at Qatar, Doha, Qatar
281
Kyungpook National University, Daegu, Korea
282
Another Institute or International Laboratory Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
283
Universiteit Antwerpen, Antwerp, Belgium
284
Yerevan Physics Institute, Yerevan, Armenia
285
Northeastern University, Boston, MA, USA
286
Imperial College, London, UK
287
Institute of Nuclear Physics of the Uzbekistan Academy of Sciences, Tashkent, Uzbekistan
288
CERN, 1211, Geneva 23, Switzerland
a
cms-publication-committee-chair@cern.ch
Received:
20
February
2024
Accepted:
25
March
2024
Published online:
14
May
2024
A search for exotic decays of the Higgs boson (
) with a mass of 125
to a pair of light pseudoscalars 
is performed in final states where one pseudoscalar decays to two 
quarks and the other to a pair of muons or 
leptons. A data sample of proton–proton collisions at 
corresponding to an integrated luminosity of 138
recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level (
) on the Higgs boson branching fraction to and to 
via a pair of s. The limits depend on the pseudoscalar mass 
and are observed to be in the range (0.17–3.3) 
and (1.7–7.7) 
in the and final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine upper limits on the branching fraction 
at 95% , with 
being a muon or a 
lepton. For different types of 2HDM+S, upper bounds on the branching fraction 
are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, values above 0.23 are excluded at 95% for values between 15 and 60.
T. Tuuva, M. Narain, S. Wimpenny, G. R. Snow, A. Vorobyev: Deceased.
© The Author(s) 2024
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