English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The one-loop level mediated $t-> c \gamma$ decay is analyzed in the frameworkof 331 models, which induce three-level flavor-changing neutral currentsmediated by an extra neutral gauge boson, Z', and a neutral scalar boson, \phi.These models also predict new charged gauge and scalar bosons, together withthree new quarks, which can be exotic (with electric charges of -4/3e and 5/3e)or standard model like. Apart from the contribution of the W boson, the $t\toc\gamma$ decay receives contributions induced by the extra gauge boson and theneutral scalar boson, which are generic for 331 models. In the so-calledminimal 331 model, there are additional contributions from the new chargedgauge and scalar bosons accompanied by the exotic quarks. We present analyticalresults for the most general $t-> c\gamma$ amplitude in terms of transcendentalfunctions. For the numerical analysis we focus on the minimal 331 model: thecurrent bounds on the model parameters are examined and a particular scenariois discussed in which the corresponding branching ratio could be of the orderof 10^{-6}, with the dominant contributions arising from the charged gaugebosons and a relatively light neutral scalar boson with flavor-changingcouplings, whereas the Z' contribution would be of the order of 10^{-9} form_{Z'}>2 TeV. However, a further suppression could be expected due to apotential suppression of the values of the flavor-changing coupling constants.Under the same assumptions, in 331 models without exotic quarks, the $t->c\gamma$ branching ratio would receive the dominant contribution from theneutral scalar boson, which could be of the order of 10^{-7} for a Higgs massof a few hundreds of GeVs.

Decay $t-> c\gamma$ in models with SU_L(3)XU_X(1) gauge symmetry