Friday, April 09, 2010

Á guide for anonymous LHC backholics

A few days ago it was published on arxiv the following paper: Black hole/string ball production, possibly at LHC

I am busy reading any, many things nowadays and I couldn't read it immediately - despite of it's few number of pages - but today, at last, I read it.

The main interest of the papers is that it makes a quick review of the ideas that lead to the proposal of black hole creation on the LHC and to it's characteristics. Most interestingly still, it gives references to the relevant literature.

One of the focus +of the paper is the way on which the Hawking radiation is expected to behave. It is said that the first expectation was that most of the radiation would be send t Kaluza-Klein models of the gaviton that scape to the bulk. In particular a paper stating that was: A Model for High Energy Scattering in Quantum Gravity (note that the article treats other aspects as well).

Later it was argued that instead there would be a lot of hawking emission into brane particles: Black Holes Radiate Mainly on the Brane . In this paper, like in the others, the treatment is semiclassical. No construction of black out of D-branes is used. Neither Hawking radiation is described by string theory objects. Such descriptions exist, to a certain extent, but are not developed enough to use them in this contexts. In fat an analytic description of a black hole in braneworlds is inexistent even in classical gravity and some reasonable approximations have to be made. This approximations are valid for small black holes whose size is much smaller than the length of the extra dimension.

The amount of radiation send to the bulk or to the brane is important. If all the radiation is send to the brane no Hawking radiation would be observed in the LHC.

Well. I think that this article is citing mainly orthodox string theory friendly papers. Be aware that other people argue that a microcanonical statistical ensemble would be necessary. In that assumptions the lifetime of the back holes could be large enough to leave the detectors (but still there woulld, of course, no danger of earth swallowing black holes).

The theme of black hole emission has behind it a lot of publications and many, many, possibilities have been conjectured. One of that is the possibility of formation of a "cromosphere" or an "electrosphere". By that it is understood that the hawking radiation reorganizes into a permanent orbiting matter that obstruct the rest of the outgoing radiation to some extent. A recent paper in arxiv (sorry, I have no time to search the reference now) argues against it.

Also there have been more exotic ideas. For example Louis Crane abrogate for the possibility of creating black holes by collapsing large clouds of dust, of a few tons, by means of implosions. He argues that the resulting black hole would emit in supersymmetric modes and that the radiation could be modulated to use the black hole as a device to impulsate spaceships able to go into other solar systems. I have discussed this, and the one of microcanonical ensembles, possibility in my other blog. You can search there for them (if you speak Spanish).

As the readers could guess some of the suggestions in the literature have more wide acceptation, possible with very good reasons, that others. And, except for the Louis Crane idea, all depends on braneworld sceneries. Recently there was an article in arxiv that gives a wide sight into realizations of that models into full string theory. When I would have read it I'll try to summarize some of the proposals here.

UPDATE: Today Lubos has commented about an article treating black holes: Kerr black hole: the CFT entropy works for all M,J. Of course it is worth reading.

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