• 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 , 22,719 comments
1,470 users with positive rep
818 active unimported users
More ...

  Why does a string connected between a D0-brane and an anti-D0-brane turn into a tachyon upon their annihilation?

+ 6 like - 0 dislike

Consider a string stretched between a D0-brane and an anti-D0-brane. In this case as the stretching energy is greater than the quantum zero point energy the string will have a positive mass. But, as the D0-brane and the anti-D0-brane come closer to annihilate the string becomes a tachyon as now the major is from quantum zero point energy as the string is no longer stretched.

But will the sudden "coming closer" of the brane and anti-brane give the string extra vibrations?

If so,is it that the energy due to these vibrations is not enough to overcome that of zero point energy finally resulting in a tachyon?

This post imported from StackExchange Physics at 2014-06-03 16:59 (UCT), posted by SE-user Rajath Krishna R
asked May 29, 2014 in Theoretical Physics by Rajath Krishna R (30 points) [ no revision ]

1 Answer

+ 2 like - 0 dislike

The D-branes in these calculations are static, the string is weakly coupled and the branes are infinitely heavy in the limit. So there are no back-reaction, there are no motion or vibrations of the branes, the whole dynamics of annihilation is just by tachyon condensation, from the point of view of the D0 anti-D0 system, there are just more and more tachyonic strings stuck on. The branes are heavy external sources in this limit.

Obviously, this tachyon condensation cannot go on forever, away from zero coupling, because the D0 branes are not really infinitely heavy. A finite number of strings have to peel off, and leave the D0 branes in an annihilated state, where they are indistinguishable from vacuum, since all the energy has gone off in the outgoing strings. From the point of view of the external theory, the branes annihilated into non-tachyonic strings, and the tachyons on the branes condensed fully, leaving behind an object which doesn't exist anymore--- the annihilated D0 brane system.

The process as calculated in the D-brane picture using perturbative strings doesn't deal with D-brane back-reaction. Ashoke Sen worked to understand the annihilation of branes from tachyon condensation, and concluded that the fully tachyon condensed branes, once the tachyon rolls to its minimum, are no longer there as far as strings are concerned, they can't interact with anything anymore, and so are indistinguishable from vacuum.

Lubos Motl has writted about this interesting story here: http://motls.blogspot.com/2012/08/ashoke-sen-and-tachyon-condensation.html , and links to the most important papers.

answered Jun 3, 2014 by Ron Maimon (7,720 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):
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