A search for exotic decays of the Higgs boson ($$\text {H}$$) with a mass of 125$$\,\text {Ge}\hspace{-.08em}\text {V}$$to a pair of light pseudoscalars $$\text {a}_{1} $$is performed in final states where one pseudoscalar decays to two $${\textrm{b}}$$quarks and the other to a pair of muons or $$\tau $$leptons. A data sample of proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$corresponding to an integrated luminosity of 138$$\,\text {fb}^{-1}$$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 ($$\text {CL}$$) on the Higgs boson branching fraction to $$\upmu \upmu \text{ b } \text{ b } $$and to $$\uptau \uptau \text{ b } \text{ b },$$via a pair of $$\text {a}_{1} $$s. The limits depend on the pseudoscalar mass $$m_{\text {a}_{1}}$$and are observed to be in the range (0.17–3.3) $$\times 10^{-4}$$and (1.7–7.7) $$\times 10^{-2}$$in the $$\upmu \upmu \text{ b } \text{ b } $$and $$\uptau \uptau \text{ b } \text{ b } $$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 $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} \rightarrow \ell \ell \text{ b } \text{ b})$$at 95% $$\text {CL}$$, with $$\ell $$being a muon or a $$\uptau $$lepton. For different types of 2HDM+S, upper bounds on the branching fraction $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$$are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$$values above 0.23 are excluded at 95% $$\text {CL}$$for $$m_{\text {a}_{1}}$$values between 15 and 60$$\,\text {Ge}\hspace{-.08em}\text {V}$$.
Search for exotic decays of the Higgs boson to a pair of pseudoscalars in the $$\upmu \upmu \text{ b } \text{ b } $$and $$\uptau \uptau \text{ b } \text{ b } $$final states
C. Aimè;S. Calzaferri;D. Fiorina;P. Montagna;C. Riccardi;P. Salvini;I. Vai;P. Vitulo;M. Pelliccioni;
2024-01-01
Abstract
A search for exotic decays of the Higgs boson ($$\text {H}$$) with a mass of 125$$\,\text {Ge}\hspace{-.08em}\text {V}$$to a pair of light pseudoscalars $$\text {a}_{1} $$is performed in final states where one pseudoscalar decays to two $${\textrm{b}}$$quarks and the other to a pair of muons or $$\tau $$leptons. A data sample of proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$corresponding to an integrated luminosity of 138$$\,\text {fb}^{-1}$$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 ($$\text {CL}$$) on the Higgs boson branching fraction to $$\upmu \upmu \text{ b } \text{ b } $$and to $$\uptau \uptau \text{ b } \text{ b },$$via a pair of $$\text {a}_{1} $$s. The limits depend on the pseudoscalar mass $$m_{\text {a}_{1}}$$and are observed to be in the range (0.17–3.3) $$\times 10^{-4}$$and (1.7–7.7) $$\times 10^{-2}$$in the $$\upmu \upmu \text{ b } \text{ b } $$and $$\uptau \uptau \text{ b } \text{ b } $$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 $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} \rightarrow \ell \ell \text{ b } \text{ b})$$at 95% $$\text {CL}$$, with $$\ell $$being a muon or a $$\uptau $$lepton. For different types of 2HDM+S, upper bounds on the branching fraction $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$$are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$$values above 0.23 are excluded at 95% $$\text {CL}$$for $$m_{\text {a}_{1}}$$values between 15 and 60$$\,\text {Ge}\hspace{-.08em}\text {V}$$.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.