Quantcast
Processing math: 100%
  • 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.
W3Counter Web Stats

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.

News

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 β tools

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

Attributions

(propose a free ad)

Site Statistics

206 submissions , 164 unreviewed
5,106 questions , 2,251 unanswered
5,413 answers , 23,081 comments
1,470 users with positive rep
822 active unimported users
More ...

  Regularization of free energy in E. Fradkin's lecture note

+ 1 like - 0 dislike
772 views

In Prof. Eduardo Fradkin's lecture, he computed the free energy (up to a divergent normalization constant) of the (d+1)-dim free massive scalar theory at finite temperature T as
F(T)=VT2ddp(2π)dn=lnβ[ω2n+|p|2+m2], (see his Eq. (5.204))


where ωn=2πn/β is the Matsubara frequency, nZ, V is the volume of the spatial part and T is the finite temperature. This summation is formally divergent. He then mentioned that we can make use of the divergent normalization constant to regularize this summation. My understanding is that we add to F(T) a constant that is also formally divergent:
Freg(T)=F(T)+A

where A is some constant and Freg(T) is the regularized free energy. And then Freg(T) will no longer be divergent (up to the VT infrared divergence). The result he gave us immediately turns out to be
Freg(T)=VTddp(2π)dln[(β(|p|2+m2)1/2)n=1(1+|p|2+m2ω2n)]. (see his Eq. (5.205))

However, I am not quite sure how to systematically obtain this result. Certainly we can work backward and find
F(T)=VT2ddp(2π)d(lnβ(|p|2+m2)+2n=1lnβ(ω2n+|p|2+m2))=VTddp(2π)dln[(β(|p|2+m2)1/2)n=1(1+|p|2+m2ω2n)]+VTddp(2π)d(12lnβ+n=1ln(βω2n))

And then we choose A in Freg(T)=F(T)+A to be
A=VTddp(2π)d(12lnβ+n=1ln(βω2n))

such that we obtain 
Freg(T)=VTddp(2π)dln[(β(|p|2+m2)1/2)n=1(1+|p|2+m2ω2n)].

But this is not a systematic way that I am seeking for. Are there any suggestions or reference that carry out this sort of regularization in details? Thanks. 

asked Apr 11, 2021 in Theoretical Physics by ocf001497 (15 points) [ no revision ]

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):
Anti-spam verification:
If you are a human please identify the position of the character covered by the symbol in the following word:
pysicsOveflow
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
...