TeV-scale Z' bosons from D-branes

Dumitru Ghilencea, Luis E. Ibáñez, Nikos Irges, Fernando Quevedo

Research output: Contribution to journalArticlepeer-review


Generic D-brane string models of particle physics predict the existence of extra U(1) gauge symmetries beyond hypercharge. These symmetries are not of the E6 class but rather include the gauging of Baryon and Lepton numbers as well as certain Peccei-Quinnlike symmetries. Some of the U(1)'s have triangle anomalies, but they are cancelled by a Green-Schwarz mechanism. The corresponding gauge bosons typically acquire a mass of order the string scale MS by combining with two-index antisymmetric fields coming from the closed string sector of the theory. We argue that in string models with a low string scale MS ∝ 1-10 TeV, the presence of these generic U(1) 's may be amenable to experimental test. Present constraints from electroweak precision data already set important bounds on the mass of these extra gauge bosons. In particular, for large classes of models, ρ-parameter constraints imply MS ≥ 1.5 TeV. In the present scheme some fraction of the experimentally measured Z0 mass would be due not to the Higgs mechanism, but rather to the mixing with these closed string fields. We give explicit formulae for recently constructed classes of intersecting D6- and D5-brane models yielding the Standard Model (SM) fermion spectrum.

Original languageEnglish (US)
Pages (from-to)303-347
Number of pages45
JournalJournal of High Energy Physics
Issue number8
StatePublished - Aug 1 2002


  • Beyond Standard Model
  • Compactification and String Models
  • D-branes
  • Extra Large Dimensions

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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