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

Abstract

A new estimate of the one loop contributions of the standard model to the chromomagnetic dipole moment (CMDM) ${\hat{\mu }}_q(q^2)$ of quarks is presented with the aim to address a few disagreements arising in previous calculations. We consider the most general case with an off-shell gluon with transfer momentum $q^2$ and obtain analytical results in terms of Feynman parameter integrals and Passarino-Veltman scalar functions, which are then expressed in terms of closed form functions when possible. The calculation is done via a renormalizable linear $R_{\xi }$ gauge and the background field method, which allows one to corroborate that the resulting ${\hat{\mu }}_q(q^2)$ is gauge independent and thus a valid observable quantity. It is found that the QCD contribution from a three-gluon Feynman diagram has an infrared divergence, which agrees with a previous evaluation and stems from the fact that the static CMDM [$\hat{\mu }(0)$] has no sense in perturbative QCD. For the numerical analysis we consider the region 30 GeV$<\Vert q\Vert <$ 1000 GeV and analyze the behavior of ${\hat{\mu }}_q(q^2)$ for all the standard model quarks. It is found that the CMDM of light quarks is considerably smaller than that of the top quark as it is directly proportional to the quark mass. In the considered energy interval, both the real and imaginary parts of ${\hat{\mu }}_t(q^2)$ are of the order of $10^{-2}-10^{-3}$, with the largest contribution arising from the QCD induced diagrams, though around the threshold $q^2=4m_t^2$ there are also important contributions from diagrams with $Z$ gauge boson and Higgs boson exchange.

References in corpus (39)

• Automatized One-Loop Calculations in 4 and D dimensions
• Electric dipole moments as probes of new physics
• New Developments in FeynCalc 9.0
• Collier: a fortran-based Complex One-Loop LIbrary in Extended Regularizations
• The three-loop QCD $\beta$-function and anomalous dimensions
• Package-X: A Mathematica package for the analytic calculation of one-loop integrals
• The analytical value of the electron (g-2) at order alpha^3 in QED
• Pinch Technique: Theory and Applications
• Application of the Background-Field Method to the electroweak Standard Model
• On the running coupling constant in QCD
• Neutron Electric Dipole Moment In The Standard Model: Valence Quark Contributions
• Constraining the dipole moments of the top quark
• Quark-gluon vertex in arbitrary gauge and dimension
• Measurement of the top quark polarization and $\mathrm{t}\bar{\mathrm{t}}$ spin correlations using dilepton final states in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Top quark spin correlations and polarization at the LHC: standard model predictions and effects of anomalous top chromo moments
• Generalized Pinch Technique and the Background Field Method in General Gauges
• Top Production in Hadron-Hadron Collisions and Anomalous Top-Gluon Couplings
• Probing the Chromoelectric and Chromomagnetic dipole moments of the Top quark at Hadronic Colliders
• Measurements of t t-bar spin correlations and top quark polarization using dilepton final states in pp collisions at sqrt(s) = 8 TeV
• Search for anomalous top-gluon couplings at LHC revisited
• Chromomagnetic Dipole Moment of the Top Quark Revisited
• The Chromoelectric Dipole Moment of the Top Quark in Models with Vector Like Multiplets
• The muon anomalous magnetic moment in QED: three-loop electron and tau contributions
• Dipole Form Factors and Loop-induced CP-violation in Supersymmetry
• The Muon g-2 in Progress
• Improved bounds on heavy quark electric dipole moments
• Top quark Chromoelectric and Chromomagnetic Dipole Moments in a Two Higgs Doublet Model with CP violation
• Singlet scalar and 2HDM extensions of the Standard Model: CP-violation and constraints from $(g-2{)}_{\mu }$ and $e$EDM
• Search for new physics in top quark production in dilepton final states in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Anomalous gtt couplings in the Littlest Higgs Model with T-parity
• Anomalous chromomagnetic moment of quarks
• Chromoelectric Dipole Moments of Quarks in MSSM Extensions
• Flavor violation in chromo- and electromagnetic dipole moments induced by $Z^{\prime }$ gauge bosons and a brief revisit of the Standard Model
• Constraints on unparticle physics from the $gt\bar{t}$ anomalous coupling
• Chromomagnetic and chromoelectric dipole moments of the top quark in the 4GTHDM
• Top quark chromomagnetic dipole moment in the littlest Higgs model with T-parity
• Electron Electric Dipole Moment in Mirror Fermion Model with Electroweak Scale Non-sterile Right-handed Neutrinos
• Lepton electric and magnetic dipole moments via lepton flavor violating spin-1 unparticle interactions
• Electric dipole moments of charged leptons at one loop in the presence of massive neutrinos

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