Invisible Z-boson decays at e+e- colliders

Marcela Carena*, André De Gouvêa, Ayres Freitas, Michael Schmitt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


The measurement of the invisible Z-boson decay width at e+e - colliders can be done "indirectly," by subtracting the Z-boson visible partial widths from the Z-boson total width, or "directly," from the process e+e -→yvv̄. Both procedures are sensitive to different types of new physics and provide information about the couplings of the neutrinos to the Z boson. At present, measurements at CERN LEP and CHARM II are capable of constraining the left-handed Zvv̄ coupling, 0.45≲gL≲0. 5, while the right-handed one is only mildly bounded, |gR|≲0.2. We show that measurements at a future e+e- linear collider at different center-of-mass energies√s=mz and √s≈170 GeV, would translate into a markedly more precise measurement of the Zvv̄ couplings. A statistically significant deviation from standard model predictions will point toward different new physics mechanisms, depending on whether the discrepancy appears in the direct or the indirect measurement of the invisible Z width. We discuss some scenarios which illustrate the ability of different invisible Z-boson decay measurements to constrain new physics beyond the standard model.

Original languageEnglish (US)
Article number113007
JournalPhysical Review D
Issue number11
StatePublished - 2003

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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