2023 Articles

Search for direct production of electroweakinos in final states with one lepton, jets and missing transverse momentum in 𝑝𝑝 collisions at √𝒔 = 13 TeV 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, Konie

Searches for electroweak production of wino-like chargino pairs, χ̃₁⁺χ̃₁⁻, and of wino-like chargino and next-to-lightest neutralino χ̃₁^±, are presented. The models explored assume that the charginos decay into a W boson and the lightest neutralino, χ̃₁^± → 𝑊^±χ̃₁⁰. The next-to-lightest neutralinos are degenerate in mass with the chargino and decay to χ̃₁⁰ and either a 𝑍 or a Higgs boson, χ̃₂⁰ → 𝑍χ̃₁⁰ or 𝒉χ̃₁⁰. The searches exploit the presence of a single isolated lepton and missing transverse momentum from the 𝑊 boson decay products and the lightest neutralinos, and the presence of jets from hadronically decaying 𝑍 or 𝑊 bosons or from the Higgs boson decaying into a pair of 𝑏-quarks. The searches use 139 fb⁻¹ of √𝒔 = 13 TeV proton-proton collisions data collected by the ATLAS detector at the Large Hadron Collider between 2015 and 2018.

No deviations from the Standard Model expectations are found, and 95% confidence level exclusion limits are set. Chargino masses ranging from 260 to 520 GeV are excluded for a massless χ̃₁⁰ in chargino pair production models. Degenerate chargino and next-to-lightest neutralino masses ranging from 260 to 420 GeV are excluded for a massless χ̃₁⁰ for χ̃₂⁰ → 𝑍χ̃₁⁰. For decays through an on-shell Higgs boson and for mass-splitting between χ̃₁^±χ̃₂⁰ and χ̃₁⁰ as small as the Higgs boson mass, mass limits are improved by up to 40 GeV in the range of 200–260 GeV and 280–470 GeV compared to previous ATLAS constraints.