2024

Search for a CP-odd Higgs boson decaying into a heavy CP-even Higgs boson and a 𝑍 boson in the 𝓁⁺𝓁⁻𝑡𝑡̄ and 𝑣𝑣̄𝑏𝑏̄ final states using 140fb⁻¹ of data collected with the ATLAS detector

Aad, G.; Abbott, B.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Adam Bourdarios, C.; Adamczyk, L.; Addepalli, S. V.; Addison, M. J.; Adelman, J.; Adiguzel, A.; Adye, T.; Affolder, A. A.; Afik, Y.; Agaras, M. N.; Agarwala, J.; Aggarwal, A.; Agheorghiesei, C.; Ahmad, A.; Ahmadov, F.; Ahmed, W. S.; Ahuja, S.; Ai, X.; Aielli, G.; Aikot, A.; Ait Tamlihat, M.; Aitbenchikh, B.; Aizenberg, I.; Akbiyik, M.; Åkesson, T. P. A.; Akimov, A. V.; Akiyama, D.; Akolkar, N. N.; Aktas, S.; Al Khoury, K.

A search for a heavy CP-odd Higgs boson, 𝐴, decaying into a 𝑍 boson and a heavy CP-even Higgs boson, 𝐻, is presented. It uses the full LHC Run 2 dataset of 𝑝𝑝 collisions at √𝒔 = 13 TeV collected with the ATLAS detector, corresponding to an integrated luminosity of 140 fb⁻¹.

The search for 𝐴 → 𝑍𝐻 is performed in the 𝓁⁺𝓁⁻𝑡𝑡̄ and 𝑣𝑣̄𝑏𝑏̄ final states and surpasses the reach of previous searches in different final states in the region with 𝑚_𝐻 > 350 GeV and 𝑚_𝐴 > 800 GeV. No significant deviation from the Standard Model expectation is found. Upper limits are placed on the production cross-section times the decay branching ratios. Limits with less model dependence are also presented as functions of the reconstructed 𝑚(𝑡𝑡̄) and 𝑚(𝑏𝑏̄) distributions in the 𝓁⁺𝓁⁻𝑡𝑡̄ and 𝑣𝑣̄𝑏𝑏̄ channels, respectively. In addition, the results are interpreted in the context of two-Higgs-doublet models.