Quantcast
  • 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.

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 \(\beta\) 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
5,103 questions , 2,249 unanswered
5,355 answers , 22,794 comments
1,470 users with positive rep
820 active unimported users
More ...

Wall for JonLester

You are simply wrong about the long wavelength behavior, and there are no two ways about it. Of course I mean "without quarks" (not that they change anything), and the behavior I am talking about is what is observed, and any claim to the contrary is irresponsible because it simply shows you have never seen a lattice gauge field simulation configuration.

The results are always uncorrelated at long distances, the product of sufficiently many link gauge-fields in any one direction are completely random and fill the gauge group, and completely uncorrelated from place to place so long as the distance is much larger than the confinement length.

It is not only true, it is uncontroversial, every pure gauge theory simulation sees this, it is the central property. I don't have patience for this, you are misinterpreting things you are reading (probably correct things), and coming to the conclusion that the gauge field at long distances is not uncorrelated. It is uncorrelated, it's a fact. Please do a simulation, it doesn't take long.
Aug 11, 2014 by Ron Maimon
Thanks for the response, I now understand what you are misunderstanding. I am not "using" the strong coupling expansion, rather I am describing what the results of this are. The strong coupling expansion is not used because there is nothing more to learn from it! It's served its purpose. The purpose was to describe what strong coupling lattice gauge theory looks like, it is now understood, and there is no more controversy about this.

The issues are about taking a continuum limit, where the coupling is weak. It is probably just as hopeless to try to approach the continuum limit from the strong coupling expansion as it is to approach the long-distance strong coupling limit from the continuum.

But the conclusions I am saying don't require any expansion at all, they are simply facts about simulations of lattice gauge theory at weak (or strong) coupling! The simulations randomize at long distances, and this means something precise--- it means that if you calculate the correlation function of <G(x) G(y)> where G is the lattice link gauge field, then it approaches zero as x and y become separated as exp(-|x-y|/L), where L is the inverse mass gap. This is the very statement of what mass-gap means.

This are set in stone, because it is simply a numerical fact. One part of the millenium problem is to prove that this is what happens at long distances, but that it is what happens at long distances is not controversial.

The rate of decay of the correlations is described well by the strong coupling expansion, but you don't need to use it to conclude that the correlations decay. When the correlations decay completely, at distances much larger than the confinement length, the configurations of the gauge fields are entirely uncorrelated.

If you superpose a large grid on top of the continuum theory, and define the lattice field as the parallel transport along the link, then the configuration of the lattice gauge theory so defined is a random sampling from an action which approaches the strong-coupling (zero action) fixed point. What that means is that the parallel transport along parallel lines is completely statistically independent when the lines are far apart (this follows from the mass gap).

Nothing I am saying can be challenged, because it is simply a numerical fact, I can show you this on a computer if you would like, but it is easier if you simulate it, or ask a lattice QCD person. The randomness of the long-wavelength gauge field is not proved by the strong coupling expansion, it is described by the strong coupling expansion. It is "proved" because it is numerically what happens in simualtions, and the goal of the Millenium problem is to get a mathematical proof, rather than a numerical demonstration through simulation.
Aug 11, 2014 by Ron Maimon
I should say "approaches zero action according to Wilson's strong coupling expansion law" rather than "has zero action". The result is obvious--- the gauge fields are random, and become more random when you multiply them to define coarser lattice link variables.
Aug 10, 2014 by Ron Maimon
Why are you asking about continuum limit? I am totally confused. The statement that the long-wavelength limit of pure lattice gauge theory is described by the action "0" is not controversial, it is the statement of mass-gap--- at distances larger than the inverse mass gap, all correlation functions in Euclidean space die off exponentially, i.e., the statistical fields are completey uncorrelated.

Taking the continuum limit makes the lattice small and the coupling logarithmically small simultaneously. If you multiply the gauge fields to find the transport matrix along a line, you can define the lattice link-variable for a coarse matrix sitting on top of the fine lattice. The coarse lattice, when it is coarser than the confinement scale, is a configuration of a strong coupling gauge theory, it has zero action.

These observations are trivial, I am completely confused why you keep giving irrelevant papers and trying to get me to read them. They are irrelevant, because I observed these things for myself, I don't need to read a thing.
Aug 10, 2014 by Ron Maimon
Oh, no, I didn't. I see now. Thanks! I was asking because the name "Jon Lester" sounded like a real name. I won't bother you again.
Aug 9, 2014 by Ron Maimon
Why is the picture you use here identical with the picture Marco Frasca uses on his website? Are you the same person? It's ok if you are, but please say so.
Aug 8, 2014 by Ron Maimon
Hi Jon,

if there are other SE and MO posts you would like to see here, you can request them to be imported here

http://www.physicsoverflow.org/4536

Regards

Dilaton
Aug 8, 2014 by Dilaton
Hi Jon, sorry for the delay. I have now assigned you as an author.

In the furure when the site has majored, users will be able to import (their) papers themself as suggested here

http://www.physicsoverflow.org/21547/importing-arxiv-papers
Aug 6, 2014 by Dilaton




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

Your rights
...