Nonexotic neutral gauge bosons
Abstract
We study theoretical and experimental constraints on electroweak theories including a new colorsinglet and electrically neutral gauge boson. We first note that the electric charges of the observed fermions imply that any such Z' boson may be described by a gauge theory in which the Abelian gauge groups are the usual hypercharge along with another U(1) component in a kineticdiagonal basis. Assuming that the observed quarks and leptons have generationindependent U(1) charges, and that no new fermions couple to the standard model gauge bosons, we find that their U(1) charges form a twoparameter family consistent with anomaly cancellation and viable fermion masses, provided there are at least three righthanded neutrinos. We then derive bounds on the Z' mass and couplings imposed by direct production and Zpole measurements. For generic charge assignments and a gauge coupling of electromagnetic strength, the strongest lower bound on the Z' mass comes from Zpole measurements, and is of the order of 1 TeV. If the new U(1) charges are proportional to BL, however, there is no treelevel mixing between the Z and Z', and the best bounds come from the absence of direct production at CERN LEP II and the Fermilab Tevatron. If the U(1) gauge coupling is one or two orders of magnitude below the electromagnetic one, these bounds are satisfied for most values of the Z' mass.
 Publication:

Physical Review D
 Pub Date:
 August 2003
 DOI:
 10.1103/PhysRevD.68.035012
 arXiv:
 arXiv:hepph/0212073
 Bibcode:
 2003PhRvD..68c5012A
 Keywords:

 12.60.Cn;
 13.66.Hk;
 14.70.Pw;
 Extensions of electroweak gauge sector;
 Production of nonstandard model particles in e<sup></sup>e<sup>+</sup> interactions;
 Other gauge bosons;
 High Energy Physics  Phenomenology;
 High Energy Physics  Experiment
 EPrint:
 26 pages, 2 figures. A comparison with the LEP bounds on sneutrino resonances is included