Search for a light pseudoscalar Higgs boson in the boosted $μμττ$ final state in proton-proton collisions at $$\sqrt{s}$$ = 13 TeV
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 H $$\to$$ aa $$\to$$ $$\mu\mu\tau\tau$$, and considers pseudoscalar masses in the range 3.6 $$\lt m_\mathrm{a}\lt$$ 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 H $$\to$$ aa $$\to$$ $$\mu\mu\tau\tau$$, down to 1.5 (2.0)$$\times10^{-4}$$ for $$m_\mathrm{H}=$$ 125 (300) GeV. Model-dependent limits on $$\mathcal{B}$$(H $$\to$$ aa) 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.
- Research Organization:
- Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Florida State Univ., Tallahassee, FL (United States); Univ. of Colorado, Boulder, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF); Kavli Foundation; Nvidia Corporation; SuperMicro Corporation; Welch Foundation; Weston Havens Foundation; USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Contributing Organization:
- CMS Collaboration
- Grant/Contract Number:
- AC02-07CH11359; C-1845; SC0019292; SC0010005
- OSTI ID:
- 1630718
- Alternate ID(s):
- OSTI ID: 1657329; OSTI ID: 1721766
- Report Number(s):
- FERMILAB-PUB-20-209-CMS; arXiv:2005.08694; CMS-HIG-18-024; CERN-EP-2020-061; oai:inspirehep.net:1796729; TRN: US2200686
- Journal Information:
- Journal of High Energy Physics (Online), Vol. 2020, Issue 8; ISSN 1029-8479
- Publisher:
- Springer BerlinCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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