# Minimal Coupling Principle

1. May 12, 2010

### micomaco86572

What is the minimal coupling principle?
Is it some sort of a prescription?

Thx

2. May 13, 2010

### ansgar

seek the simplest form of any interaction term

3. May 13, 2010

### micomaco86572

got it， thx

4. May 13, 2010

### Meir Achuz

"Minimal Coupling" usually refers to the introduction of the electromagnetic interaction by the transformation p --> (p-q A).

5. May 13, 2010

### xepma

And for the record, non-minimal couplings do exist and pop up when you consider effective interactions between composite charged objects and the gauge field.

An example is the interaction of the neutron with the eletromagnetic field: the neutron has zero electrical charge, but non-zero magnetic moment and therefore still couples to the electromagnetic field. This coupling is non-minimal with respect to some effective neutron-field.

A similar idea applies to zero-charged mesons (i.e. the neutral pi particle)

In the end, this non-minimal coupling arises because the neutron is made up out of three quarks who do couple minimally to the electromagnetic field.

Last edited: May 13, 2010