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

205 submissions , 163 unreviewed
5,047 questions , 2,200 unanswered
5,345 answers , 22,709 comments
1,470 users with positive rep
816 active unimported users
More ...

  Confinement of charged tachyons in AdS spacetime

+ 3 like - 0 dislike
689 views

It is well known that the negative cosmological constant of AdS spacetime can act like a confining potential. That is, in contrast to asymptotically flat spacetime, in an asymptotically AdS spacetime massive particles cannot escape to infinity. However, massless particles can escape to infinity and actually do so in a finite time.

As tachyons travel faster than massless particles, is it true that all tachyons can escape to infinity as well?

If the answer is yes, then I have some trouble understanding the following argument in a paper by Horowitz on holographic superconductivity (see here). Here, the considered action of the holographic dual to the superconductor (the bulk action) is

$S=\int d^4x\sqrt{-g}\left(R+\frac{6}{L^2}-\frac{1}{4}F_{\mu\nu}F^{\mu\nu}-|\nabla\Psi-iqA\Psi|^2-m^2|\Psi|^2\right)$,

i.e., a complex scalar field $\Psi$ and a Maxwell field $A_t$ (electric) coupled to gravity. The effective mass for $\Psi$ following from this action is $m_{eff}^2=m^2+q^2g^{tt}A_t^2$.

In constructing this dual theory, Horowitz argues that "In AdS, the charged particles cannot escape, since the negative cosmological constant acts like a confining box, and they settle outside the horizon." (Of course, only for particles for which the sign of the charge is the same as that of the black hole.)

However, the case considered subsequently is $m^2=-\frac{2}{L^2}$, which implies that $m_{eff}^2<0$ since also $g^{tt}<0$. Hence they consider tachyons!

Being tachyons, how can these particles settle outside the horizon? Why would they be confined by the cosmological constant rather than escape to infinity?

EDIT: right now I'm actually questioning my claim that all tachyons automatically travel faster than light...

This post imported from StackExchange Physics at 2014-07-08 08:15 (UCT), posted by SE-user ScroogeMcDuck
asked Jul 7, 2014 in Theoretical Physics by ScroogeMcDuck (40 points) [ no revision ]
Could you please give a link to the paper?

This post imported from StackExchange Physics at 2014-07-08 08:15 (UCT), posted by SE-user Frederic Brünner
@FredericBrünner I added the link. Specifically, the quote and the choice of $m^2$ are on page 6.

This post imported from StackExchange Physics at 2014-07-08 08:15 (UCT), posted by SE-user ScroogeMcDuck

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:
p$\hbar$ysicsOv$\varnothing$rflow
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
...