Dear all,(adsbygoogle = window.adsbygoogle || []).push({});

I have a formula at hand but I don't know how to derive it.

[tex]:e^{ik\cdot X(x)}::e^{ik'\cdot X(x')}:

= \exp\{-k_\mu k'_\nu\langle X^\mu(x)X^\nu(x')\rangle\}

:\exp\{ik\cdot X(x)+ik'\cdot X(x')\}:[/tex]

where [tex]::[/tex] denotes normal ordering, and [tex]X^\mu(x)[/tex] is the field. [tex]\langle X^\mu(x)X^\nu(x')\rangle[/tex] is the propagator.

I met this problem in the study of vertex operators of string theory. I think this is a field theory stuff but I just can't derive it.

Any help will be appreciated.

**Physics Forums - The Fusion of Science and Community**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Normal ordering and Wick contraction?

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

Loading...

Similar Threads for Normal ordering Wick | Date |
---|---|

I Vacuum cutoff, normal ordering, Planck scale and 10^120... | Mar 6, 2017 |

A Canonical quantisation of the EM field | Aug 3, 2016 |

Normal ordering in an interacting field theory | Dec 5, 2014 |

About Normal Ordering | Mar 8, 2014 |

Normal ordering versus no normal ordering | Feb 27, 2014 |

**Physics Forums - The Fusion of Science and Community**