Flavor changing effects in theories with a heavy Z ′ boson with family nonuniversal couplings

By P. Langacker, M. Plumacher. 2000

314 citations recorded by the source corpus.

There are theoretical and phenomenological motivations that there may exist additional heavy ${Z}^{\ensuremath{'}}$ bosons with family nonuniversal couplings. Flavor mixing in the quark and lepton sectors will then lead to flavor changing couplings of the heavy ${Z}^{\ensuremath{'}},$ and also of the ordinary Z when ${Z\ensuremath{-}Z}^{\ensuremath{'}}$ mixing is included. The general formalism of such effects is described, and applications are made to a variety of flavor changing and CP-violating tree and loop processes. Results are described for three specific cases motivated by a specific heterotic string model and by phenomenological considerations, including cases in which all three families have different couplings, and those in which the first two families, but not the third, have the same couplings. Even within a specific theory the results are model dependent because of unknown quark and lepton mixing matrices. However, assuming that typical mixings are comparable to the Cabibbo-Kobayashi-Maskawa matrix, processes such as coherent \ensuremath{\mu}-e conversion in a muonic atom, ${K}^{0}\ensuremath{-}{K}^{0}$ and $B\ensuremath{-}\overline{B}$ mixing, \ensuremath{\epsilon}, and ${\ensuremath{\epsilon}}^{\ensuremath{'}}/\ensuremath{\epsilon}$ lead to significant constraints on ${Z}^{\ensuremath{'}}$ bosons in the theoretically and phenomenologically motivated range ${M}_{{Z}^{\ensuremath{'}}}\ensuremath{\sim}1\mathrm{TeV}.$

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/4714f5e7d6698b7d212e685e96a7777b4d2ccdc3

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In Nuclear and High Energy Physics

Citations in the corpus

New strategies for new physics search in B → K*νν̄, B → Kνν̄ and B → Xsνν̄ decays (2009, background): “Such couplings can arise either as eective couplings induced by loop eects of particles charged under the U(1) 0 , or even at tree level in the case of generation non-universal U(1) 0 charges of the quarks [ 58 ].”
Model-independent constraints on new physics in b → s transitions (2011, background): “Prominent examples are the SM with four non-sequential generations of quarks and models with an extra U(1) symmetry [89, 90].”
A Call for New Physics : The Muon Anomalous Magnetic Moment and Lepton Flavor Violation (2016, methodology): “We point out that in scenarios of non-universal couplings, LFV can be present via a Z ′ as discussed in [232].”
New physics in B→K∗μμ? (2013, background): “Tree-level flavour changing couplings of a Z ′ can arise for example in U(1)′ models with family non-universal charges [43], in the “little flavor” model [44], and also in the “effective Z ′” setup [45], where the Z ′ couples to SM particles only through higher dimensional operators.”
The anatomy of quark flavour observables in 331 models in the flavour precision era (2012, methodology): “Also lower bounds on MZ′ were discussed in literature, stemming from study of μ decay within the model [35,38,39], from the analysis of S, T , U parameters [33] and from comparison with experimental results from CDF Collaboration for possible Z ′ decays to e+ e− or μ+μ− [40].”