Search for exotic decays of the Higgs boson to a pair of pseudoscalars in the $$\upmu \upmu \text{ b } \text{ b } $$ μ μ b b and $$\uptau \uptau \text{ b } \text{ b } $$ τ τ b b final states

• Published in: The European physical journal. C, Particles and fields Vol. 84; no. 5; pp. 1 - 38
• Main Authors: CMS Collaboration, A. Hayrapetyan, A. Tumasyan, W. Adam, J. W. Andrejkovic, T. Bergauer, S. Chatterjee, K. Damanakis, M. Dragicevic, A. Escalante Del Valle, P. S. Hussain, M. Jeitler, N. Krammer, D. Liko, I. Mikulec, J. Schieck, R. Schöfbeck, D. Schwarz, M. Sonawane, S. Templ, W. Waltenberger, C.-E. Wulz, M. R. Darwish, T. Janssen, P. Van Mechelen, E. S. Bols, J. D’Hondt, S. Dansana, A. De Moor, M. Delcourt, H. El Faham, S. Lowette, I. Makarenko, D. Müller, A. R. Sahasransu, S. Tavernier, M. Tytgat, S. Van Putte, D. Vannerom, B. Clerbaux, G. De Lentdecker, L. Favart, D. Hohov, J. Jaramillo, A. Khalilzadeh, K. Lee, M. Mahdavikhorrami, A. Malara, S. Paredes, L. Pétré, N. Postiau, L. Thomas, M. Vanden Bemden, C. Vander Velde, P. Vanlaer, M. De Coen, D. Dobur, Y. Hong, J. Knolle, L. Lambrecht, G. Mestdach, C. Rendón, A. Samalan, K. Skovpen, N. Van Den Bossche, L. Wezenbeek, A. Benecke, G. Bruno, C. Caputo, C. Delaere, I. S. Donertas, A. Giammanco, K. Jaffel, Sa. Jain, V. Lemaitre, J. Lidrych, P. Mastrapasqua, K. Mondal, T. T. Tran, S. Wertz, G. A. Alves, E. Coelho, C. Hensel, T. Menezes De Oliveira, A. Moraes, P. Rebello Teles, M. Soeiro, W. L. Aldá Júnior, M. Alves Gallo Pereira, M. Barroso Ferreira Filho, H. Brandao Malbouisson, W. Carvalho, J. Chinellato, E. M. Da Costa, G. G. Da Silveira, D. De Jesus Damiao, S. Fonseca De Souza, J. Martins, C. Mora Herrera, K. Mota Amarilo
• Format: Journal Article
• Language: English
• Published: SpringerOpen 01.05.2024
• ISSN: 1434-6052
• DOI: 10.1140/epjc/s10052-024-12727-4

Abstract A search for exotic decays of the Higgs boson ( $$\text {H}$$ H ) with a mass of 125 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V to a pair of light pseudoscalars $$\text {a}_{1} $$ a 1 is performed in final states where one pseudoscalar decays to two $${\textrm{b}}$$ b quarks and the other to a pair of muons or $$\tau $$ τ leptons. A data sample of proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$ s = 13 Te V corresponding to an integrated luminosity of 138 $$\,\text {fb}^{-1}$$ fb - 1 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 ( $$\text {CL}$$ CL ) on the Higgs boson branching fraction to $$\upmu \upmu \text{ b } \text{ b } $$ μ μ b b and to $$\uptau \uptau \text{ b } \text{ b },$$ τ τ b b , via a pair of $$\text {a}_{1} $$ a 1 s. The limits depend on the pseudoscalar mass $$m_{\text {a}_{1}}$$ m a 1 and are observed to be in the range (0.17–3.3)  $$\times 10^{-4}$$ × 10 - 4 and (1.7–7.7)  $$\times 10^{-2}$$ × 10 - 2 in the $$\upmu \upmu \text{ b } \text{ b } $$ μ μ b b and $$\uptau \uptau \text{ b } \text{ b } $$ τ τ b b 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 $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} \rightarrow \ell \ell \text{ b } \text{ b})$$ B ( H → a 1 a 1 → ℓ ℓ b b ) at 95% $$\text {CL}$$ CL , with $$\ell $$ ℓ being a muon or a $$\uptau $$ τ lepton. For different types of 2HDM+S, upper bounds on the branching fraction $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$$ B ( H → a 1 a 1 ) are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$$ B ( H → a 1 a 1 ) values above 0.23 are excluded at 95% $$\text {CL}$$ CL for $$m_{\text {a}_{1}}$$ m a 1 values between 15 and 60 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V .