• Register
PhysicsOverflow is a next-generation academic platform for physicists and astronomers, including a community peer review system and a postgraduate-level discussion forum analogous to MathOverflow.

Welcome to PhysicsOverflow! PhysicsOverflow is an open platform for community peer review and graduate-level Physics discussion.

Please help promote PhysicsOverflow ads elsewhere if you like it.


PO is now at the Physics Department of Bielefeld University!

New printer friendly PO pages!

Migration to Bielefeld University was successful!

Please vote for this year's PhysicsOverflow ads!

Please do help out in categorising submissions. Submit a paper to PhysicsOverflow!

... see more

Tools for paper authors

Submit paper
Claim Paper Authorship

Tools for SE users

Search User
Reclaim SE Account
Request Account Merger
Nativise imported posts
Claim post (deleted users)
Import SE post

Users whose questions have been imported from Physics Stack Exchange, Theoretical Physics Stack Exchange, or any other Stack Exchange site are kindly requested to reclaim their account and not to register as a new user.

Public \(\beta\) tools

Report a bug with a feature
Request a new functionality
404 page design
Send feedback


(propose a free ad)

Site Statistics

205 submissions , 163 unreviewed
5,054 questions , 2,207 unanswered
5,345 answers , 22,720 comments
1,470 users with positive rep
818 active unimported users
More ...

  How to derive the scaling transformation?

+ 3 like - 0 dislike

The question arose while reading  the Book of Subir Sachdev, Quantum Phase transition (second edition), p46. 

Given a partition function of the form 

\({\cal Z}= \int{\cal D}\phi_{\alpha}(x)\exp(-\frac{1}{2}\int d^{D}x[(\nabla_{x}\phi_{\alpha})^{2}+r\phi_{\alpha}(x)^{2}]) \)

where \(r\) is some parameter in the theory.  How one could guess the form of scaling transfromation which does not change  correlations associated with this partition function. Does it depends on the field theory or on the physical system for which the theory has been constructed?

asked Aug 3, 2014 in Theoretical Physics by Quant_Phys (55 points) [ no revision ]

1 Answer

+ 2 like - 0 dislike

As I understand it, scaling transformation are universally defined by the scaling parameter ($\lambda > 0$) such that spacetime transforms as

\(D(\lambda): \mathbb{R}^n \rightarrow \mathbb{R}^n\)

\(x \rightarrow \lambda x\)

and (components of) fields present in the theory transform according to their scaling dimension $d_{\phi}$ as

\((D(\lambda)\phi) (x )= \lambda^{-d_{\phi}} \phi(\lambda^{-1}x)\)

As Arnold said, the scaling dimension of the fields (components) can be determined by the requirement that the exponent of the path integral has scaling dimension zero.

answered Aug 3, 2014 by Dilaton (6,240 points) [ no revision ]
edited Aug 3, 2014 by Dilaton

And $d_\phi$ is determined by the action through the requirement that the exponent of the path integral has scaling dimension zero.

Your answer

Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
Please consult the FAQ for as to how to format your post.
This is the answer box; if you want to write a comment instead, please use the 'add comment' button.
Live preview (may slow down editor)   Preview
Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:
Then drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds).
Please complete the anti-spam verification

user contributions licensed under cc by-sa 3.0 with attribution required

Your rights