## Wednesday, October 27, 2010

### Multitasking in landscape decays

Adam R. Brown and Alex Dahlen of Princeton University released two preprints today:
Bubbles of Nothing and the Fastest Decay in the Landscape

Giant Leaps and Monkey Branes in Multi-Dimensional Flux Landscapes
You could say that the first preprint is non-stringy while the second preprint is stringy. But of them argue that the decays of the flux vacua in the stringy landscape proceed differently than many people expect.

Also, both of them argue that the reduction of the flux by many units is preferred as long as there exist many kinds of fluxes. The first preprint moreover uses a six-dimensional field-theoretical model and argues that in the limit in which all the types of fluxes get eliminated simultaneously, the radion (scalar field that measures the size) ceases to be stabilized against the collapse and the process reduces to the bubble of nothing.

(This sounds pretty dramatic because the bubble of nothing brutally changes the geometry and not just the electromagnetic fields but you have to read their article before concluding that this statement is nonsense.)

The second paper looks at the situation from the perspective of branes in string theory. It abandons all thin-wall approximations and discusses the role of "monkey branes" in the stimulation of the decay. They're called in this way because they wrap the toroidal and other extra dimensions multiply times, along tilted submanifolds, just like a prehensile tail. That's quite a justification of their terminology!

Don't try it in your bathroom...

Needless to say, I would call them - and I have de facto called them in literature - screwing branes for the same reason. :-)

In this landscape business, people have been very sloppy very often and the sloppiness hasn't quite gone away. So people have always assumed their most naive field-theoretical expectations. They would unite their most brutal pre-stringy approximations with their philosophical and other preconceptions and they would argue that the result was a prediction of string theory.

Well, if you abandon most technical features of string theory, then your predictions for extreme phenomena such as the vacuum decay - induced by near-Planckian variations on the manifolds - will not be too stringy, either. You shouldn't blame poor string theory for predictions that probably don't have much to do with your reasoning.

Of course, these authors are not quite the first ones who discuss the simultaneous reduction of many kinds of fluxes in the flux vacua. This blog has discussed other papers of this class, too. If you're interested, you may try to look for them by browsing the landscape category.