What is Chromoelectric dipole moment?

[Sehwook Lee]

Basically, I wonder what Chromoelectric dipole moment is and how it is formed...

 

[Einj]

It is exactly the same thing as an electric dipole moment, but it's generated from color field. Therefore you must be careful about non-commutativity of the charges

 

[ChrisVer]

The Electric Dipole Moment $\vec{d}_f$ of some particle $f$, is defined by its interaction with an electric field $\vec{E}$:

$H_{EDM} = - \vec{d}_f \cdot \vec{E}$

For a spin-1/2 particle, this corresponds to the effective lagrangian density:

$\mathcal{L}_{EDM} = \frac{-i}{2} d_f F_{\mu \nu} \bar{\psi}_f \sigma^{\mu \nu} \gamma^5 \psi_f$

you can have a similar term if you look at quarks $\mathcal{q}_r$, by replacing the electromagnetism with strong ints:

$\mathcal{L}_{CEDM} = \frac{-i}{2} d_r^{CEDM} G_{\mu \nu}^a \bar{\mathcal{q}}_r \sigma^{\mu \nu} \gamma^5 \frac{\lambda^a}{2} \mathcal{q}_r$

and that's how it arises... In general both EDMs and CEDMs generate P and T (so CP) violations.