Interpretation of angular distributions of Z-boson production at colliders

Jen Chieh Peng, Wen Chen Chang, Randall Evan McClellan, Oleg Teryaev

Research output: Contribution to journalArticlepeer-review


High precision data of dilepton angular distributions in γ*/Z production were reported recently by the CMS Collaboration covering a broad range of the dilepton transverse momentum, qT, up to ~300 GeV. Pronounced qT dependencies of the λ and ν parameters, characterizing the cos2 θ and cos 2φ angular distributions, were found. Violation of the Lam-Tung relation was also clearly observed. We show that the qT dependence of λ allows a determination of the relative contributions of the qq annihilation versus the qG Compton process. The violation of the Lam-Tung relation is attributed to the presence of a non-zero component of the q-q axis in the direction normal to the "hadron plane" formed by the colliding hadrons. The magnitude of the violation of the Lam-Tung relation is shown to reflect the amount of this 'non-coplanarity". The observed qT dependencies of λ and ν from the CMS and the earlier CDF data can be well described using this approach.

Original languageEnglish (US)
Pages (from-to)384-388
Number of pages5
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
StatePublished - Jul 10 2016


  • Drell-Yan process
  • Lam-Tung relation
  • QCD

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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