Studies of the Energy Dependence of Diboson Polarization Fractions and the Radiation-Amplitude-Zero Effect in WZ Production with the ATLAS Detector


Aad G., Aakvaag E., Abbott B., Abeling K., Abicht N., Abidi S., ...Daha Fazla

Physical Review Letters, cilt.133, sa.10, 2024 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 133 Sayı: 10
  • Basım Tarihi: 2024
  • Doi Numarası: 10.1103/physrevlett.133.101802
  • Dergi Adı: Physical Review Letters
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, Compendex, INSPEC, zbMATH, DIALNET, Nature Index
  • Ankara Üniversitesi Adresli: Evet

Özet

This Letter presents the first study of the energy dependence of diboson polarization fractions in WZ → ℓνℓ′ℓ′(ℓ,ℓ′ = e; μ) production. The dataset used corresponds to an integrated luminosity of 140 fb−1 of proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector. Two fiducial regions with an enhanced presence of events featuring two longitudinally polarized bosons are defined. A nonzero fraction of events with two longitudinally polarized bosons is measured with an observed significance of 5.3 standard deviations in the region with 100 < pZT ≤ 200 GeV and 1.6 standard deviations in the region with pZT > 200 GeV, where pZT is the transverse momentum of the Z boson. This Letter also reports the first study of the radiation-amplitude-zero effect. Events with two transversely polarized bosons are analyzed for the ΔY(ℓWZ) and ΔYℓWZ) distributions defined respectively as the rapidity difference between the lepton from the W boson decay and the Z boson and the rapidity difference between the W boson and the Z boson. Significant suppression of events near zero is observed in both distributions. Unfolded ΔY(ℓWZ) and ΔY(WZ) distributions are also measured and compared to theoretical predictions.