String theory
23. Eye on ArXiv: 21 Apr 2008 – SUSY/non-SUSY duality
And so the new week began… Would be fun to finish another paper till Friday (the subject is “IR divergencies in de Sitter space”). In the mean time, let us take a closer look on some papers released to arxives during the previous week.
Read more on 23. Eye on ArXiv: 21 Apr 2008 – SUSY/non-SUSY duality…
22. About decoherence in quasi de Sitter space
My discussion of disorder on the landscape with Lubos continues (L – Lubos, D – me).
L: So if I understand well, your degree of freedom is really the inflaton phi, and it is one degree of freedom per Hubble patch, with one expectation value and one variation. The value of the inflaton is assumed to directly control the Hubble constant and the size of the patch, according to the normal equations.
Read more on 22. About decoherence in quasi de Sitter space…
21. About probabilities in cosmology (and general) and in stochastic inflation in particular
Discussion was initiated by the question “what is the physical meaning of time 
in vacuum dynamics equations” that was smoothly transformed into the question “what is the meaning of probability 
in the vacuum dynamics equations”. My answer was that is the world time for the 4-dim observer and is the probability for him to measure a given value of the cosmological constant. Lubos replied:
20. More on KS throat cloaking…
Was thinking about recent paper by Alex Buchel and Lev Kofman… and found that I have a couple of naive questions:
1) cloaking is 5 dim picture (well, 10-dim) – i.e., throat for bulk CY observer is seen as AdS black hole. What is the picture for 4dim observer, the one who lives on the brane and whose spacetime is approximately dS? For example, I don’t quite understand what this black hole cloaking means for eternal inflation 4 dim observer experiences… Does cloaking mean that the value of the inflaton field cannot become too large?
Read more on 20. More on KS throat cloaking……
19. Disorder on the landscape: non-technical intro
Today I will kindly allow myself a bit of selfpromotion 
As I said yesterday, our paper “Disorder on the landscape” is finally out (by the way, Lubos Motl already has a very nice post about it on his blog).
Read more on 19. Disorder on the landscape: non-technical intro…
18. Eye on ArXiv: 15 Apr 2008 – Transplanckian physics, brane cosmology and holographic mesons
Sorry for being quiet for so long. The reason is we were finising a paper, asked for comments and got a lot of them. The paper is finally submitted to appear on ArXiv in tomorrow’s listings. The title is “Disorder on the landscape”, and the abstract will be available tonight Helsinki time (and tomorrow for you, my humble US readers ) Also, I hope to discuss the paper tomorrow on this blog.
15. Anderson localization. Just crossed my mind…
I personally consider Anderson localization as one of the most prominent dynamic vacuum selection principles on the string theory landscape. Let me remind you the main idea behind it.
In condensed matter theory, Anderson localization was first discovered as a phenomenon of electron wave function localization inside a semiconductor when disorder (for example, impurities or defects) of the effective potential electrons are moving in is sufficiently strong. Physics of Anderson localization in a semiconductor is related to existence of impurities with potential so strong that they bind the Bloch wave function of the electron propagating in a disordered medium. Mechanism responsible for the localization of the single electron wave function near such impurities is interference between Bloch waves scattered by impurities (defects).
Read more on 15. Anderson localization. Just crossed my mind……
12. Eye on ArXiv: 4 Apr 2008 – KS throat cloaking, non-gaussianity and Mathur’s fuzzballs
1. Alex Buchel, Lev Kofman “Black Universe epoch in string cosmology”
Alex and Lev write about multithroat scenario in string cosmology. As we remember, typically one needs more than a single throat in KKLMMT-type scenarios because the single throat setup does not solve the hierarchy problem (the energy scale of the throat is inflationary, while we naturally need a TeV scale of the Standard Model after the end of inflation). In two throat scenario history of the Universe looks as follows:
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