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

A new estimate of the one loop contributions of the standard model to thechromomagnetic dipole moment (CMDM) $\hat \mu_q(q^2)$ of quarks is presentedwith the aim to address a few disagreements arising in previous calculations.We consider the most general case with an off-shell gluon with transfermomentum $q^2$ and obtain analytical results in terms of Feynman parameterintegrals and Passarino-Veltman scalar functions, which are then expressed interms of closed form functions when possible. The calculation is done via arenormalizable linear $R_\xi$ gauge and the background field method, whichallows one to corroborate that the resulting $\hat \mu_q(q^2)$ is gaugeindependent and thus a valid observable quantity. It is found that the QCDcontribution from a three-gluon Feynman diagram has an infrared divergence,which agrees with a previous evaluation and stems from the fact that the staticCMDM [$\hat\mu(0)$] has no sense in perturbative QCD. For the numericalanalysis we consider the region 30 GeV$<\|q\|<$ 1000 GeV and analyze thebehavior of $\hat \mu_q(q^2)$ for all the standard model quarks. It is foundthat the CMDM of light quarks is considerably smaller than that of the topquark as it is directly proportional to the quark mass. In the consideredenergy interval, both the real and imaginary parts of $\hat\mu_t(q^2)$ are ofthe order of $10^{-2}-10^{-3}$, with the largest contribution arising from theQCD induced diagrams, though around the threshold $q^2=4m_t^2$ there are alsoimportant contributions from diagrams with $Z$ gauge boson and Higgs bosonexchange.

New estimate of the chromomagnetic dipole moment of quarks in the standard model