2025 Articles

Differential cross-section measurements of Higgs boson production in the 𝐻 → 𝜏⁺𝜏⁻ decay channel in 𝑝𝑝 collisions at √𝑠 = 13 TeV with the ATLAS detector

Aad, G.; Aakvaag, E.; Abbott, B.; Abdelhameed, S.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboelela, M.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Ackermann, A.; 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.; Ahmadov, F.; Ahmed, W. S.; Ahuja, S.; Ai, X.; Aielli, G.; Aikot, A.; Ait Tamlihat, M.; Aitbenchikh, B.; Akbiyik, M.; Åkesson, T. P. A.; Akimov, A. V.; Akiyama, D.; Akolkar, N. N.; Al Khoury, Konie; Angerami, Aaron; Brooijmans, Gustaaf H.; Busch, Elena Laura

Differential measurements of Higgs boson production in the 𝜏-lepton-pair decay channel are presented in the gluon fusion, vector-boson fusion (VBF), 𝑉𝐻 and 𝑡𝑡̄𝐻 associated production modes, with particular focus on the VBF production mode. The data used to perform the measurements correspond to 140 fb⁻¹ of proton-proton collisions collected by the ATLAS experiment at the LHC.

Two methods are used to perform the measurements: the 𝘚𝘪𝘮𝘱𝘭𝘪𝘧𝘪𝘦𝘥 𝘛𝘦𝘮𝘱𝘭𝘢𝘵𝘦 𝘊𝘳𝘰𝘴𝘴-𝘚𝘦𝘤𝘵𝘪𝘰𝘯 (STXS) approach and an 𝘜𝘯𝘧𝘰𝘭𝘥𝘦𝘥 𝘍𝘪𝘥𝘶𝘤𝘪𝘢𝘭 𝘋𝘪𝘧𝘧𝘦𝘳𝘦𝘯𝘵𝘪𝘢𝘭 measurement considering only the VBF phase space. For the STXS measurement, events are categorized by their production mode and kinematic properties such as the Higgs boson’s transverse momentum ( 𝑝^𝖧_T), the number of jets produced in association with the Higgs boson, or the invariant mass of the two leading jets (𝑚_𝑗𝑗). For the VBF production mode, the ratio of the measured cross-section to the Standard Model prediction for 𝑚_𝑗𝑗 > 1.5 TeV and 𝑝^𝖧_T > 200 GeV (𝑝^𝖧_T < 200 GeV) is 1.29⁺⁰˙³⁹₋₀.₃₄ (0.12⁺⁰˙³⁴₋₀.₃₃). This is the first VBF measurement for the higher- p T H criteria, and the most precise for the lower-𝑝^𝖧_T criteria.

The 𝘧𝘪𝘥𝘶𝘤𝘪𝘢𝘭 cross-section measurements, which only consider the kinematic properties of the event, are performed as functions of variables characterizing the VBF topology, such as the signed ∆𝜑_𝘫𝘫 between the two leading jets. The measurements have a precision of 30%–50% and agree well with the Standard Model predictions. These results are interpreted in the SMEFT framework, and place the strongest constraints to date on the CP-odd Wilson coefficient 𝘤_𝐻𝑊̃.