Nonexotic Neutral Gauge Bosons

By T. Appelquist, B. Dobrescu, A. Hopper. 2002

220 citations recorded by the source corpus.

We study theoretical and experimental constraints on electroweak theories including a new color-singlet 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 kinetic-diagonal basis. Assuming that the observed quarks and leptons have generation-independent U(1) charges, and that no new fermions couple to the standard model gauge bosons, we find that their U(1) charges form a two-parameter family consistent with anomaly cancellation and viable fermion masses, provided there are at least three right-handed neutrinos. We then derive bounds on the Z' mass and couplings imposed by direct production and Z-pole measurements. For generic charge assignments and a gauge coupling of electromagnetic strength, the strongest lower bound on the Z' mass comes from Z-pole measurements, and is of order 1 TeV. If the new U(1) charges are proportional to B-L, however, there is no tree-level mixing between the Z and Z', and the best bounds come from the absence of direct production at LEPII and the 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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/790a98ee00dc4c7d9629b7e544b70156f8785183

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Citations in the corpus

Search for New Physics with Atoms and Molecules (2017, background): “If paraphotons couple directly to standard model particles, in order to generate fermion masses and avoid gauge anomalies (quantum corrections that break the gauge symmetry and lead to theoretical inconsistencies), the gauge symmetry corresponding to the paraphoton must be U(1)B−L (Appelquist et al.”
Spin-dependent macroscopic forces from new particle exchange (2006, background): “[31]), where the set of values for zl, ze, zq, zu, and zd is restricted such that g V,A + g e V,A = 0 , g V,A = gz 2 [(4 ± 3) zq − zu] .”
The Dark Photon (2020, background): “(1) but the mass term between the dark photon and the Zboson is taken non-diagonal and therefore giving a mixing between these two states (Appelquist et al., 2003; Babu et al., 1998; Davoudiasl et al., 2012; Galison and Manohar, 1984; He et al., 1991).”
Implications of unitarity and gauge invariance for simplified dark matter models (2015, background): “ich give severe constraints. In principle also electron-positron colliders can constrain this scenario eciently. Limits on a Z0lighter than 209 GeV derived from LEP data imply g. 10 2 [62] (see also [63,64]). We do not include LEP constraints here since other constraints will turn out to be at least”