Measurement of the $H\to {\hat{I}}^3{\hat{I}}^3$ and $H\to Z{Z}^{\ast }\to 4\ell$ cross-sections in $pp$ collisions at $\sqrt{s}=13.6$ TeV with the ATLAS detector

Abstract

The inclusive Higgs boson production cross-section is measured in the di-photon and the $Z{Z}^{\ast }\to 4\ell$ decay channels using 31.4 and 29.0 fb${}^{-1}$ of $pp$ collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of $\sqrt{s}=13.6$ TeV. To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the channel's detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are $\ddot{I}{ƒ}_{\mathrm{fid},{\hat{I}}^3{\hat{I}}^3}=76_{-13}^{+14}$ fb, and $\ddot{I}{ƒ}_{\mathrm{fid},4\ell }=2.80\pm 0.74$ fb, in agreement with the corresponding Standard Model predictions of $67.6\pm 3.7$ fb and $3.67\pm 0.19$ fb. Assuming Standard Model acceptances and branching fractions for the two channels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of $\ddot{I}ƒ(pp\to H)=67_{-11}^{+12}$ pb and $46\pm 12$ pb at $13.6$ TeV from the di-photon and $Z{Z}^{\ast }\to 4\ell$ measurements respectively. The two measurements are combined into a total cross-section measurement of $\ddot{I}ƒ(pp\to H)=58.2\pm 8.7$ pb, to be compared with the Standard Model prediction of $\ddot{I}ƒ(pp\to H{)}_{\mathrm{SM}}=59.9\pm 2.6$ pb.

51 pages in total, author list starting page 34, 3 figures, 7 tables, published in EPJC. All figures and tables including auxiliary figures and tables are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2022-12/