definition of light in string theory

[dubmugga]

What is it ?

Is it an excitation of a string in an extra dimension causing an effect of particle and wave nature in our universe ?

What also it it's definition in LQG or CDT ?

:confused:

[Alamino]

If I can remember my string classes, the photon should be an vibration mode of the string as all other particles. In LQG I guess that it is simply the usual gauge field of QED as LQG only quantize gravity. This should be the case in CDT too. LQG and CDT only deal with quantum gravity, not the other interactions at this moment.