D5D5-brane type I superstring background fields in terms of type IIB ones by canonical method and T-duality approach

We consider type IIB superstring theory with embedded $D5$-brane and choose boundary conditions which preserve half of the initial supersymmetry. In the canonical approach that we use, boundary conditions are treated as canonical constraints. The effective theory, obtained from the initial one on the solution of boundary conditions, has the form of the type I superstring theory with embedded $D5$-brane. We obtain the expressions for $D5$-brane background fields of type I theory in terms of the $D5$-brane background fields of type IIB theory. We show that beside known $\Omega$ even fields, they contain squares of $\Omega$ odd ones, where $\Omega$ is world-sheet parity transformation, $\Omega:\sigma\to -\sigma$. We relate result of this paper and the results of [1] using T-dualities along four directions orthogonal to $D5$-brane

Lower-dimensional pure-spinor superstrings

We study to what extent it is possible to generalise Berkovits' pure-spinor construction in d=10 to lower dimensions. Using a suitable definition of a ``pure'' spinor in d=4,6, we propose models analogous to the d=10 pure-spinor superstring in these dimensions. Similar models in d=2,3 are also briefly discussed.Comment: 17 page

The Music Market in the Age of Download

Internet, mp3 files, peer-to-peer software and digital technologies for copying have radically modified the music sector. In this paper I present a theoretical model, that investigates the consequences of the appearance of a pirate low quality good (typically a mp3 file) in the music market. In this paper I propose a model of sampling, consider the possibility that the firm modifies its business entering into the low quality segment and investigate the supposed conflict between the recording company, whose profit depends on the CD sold, and the artist, whose profits depend in part on the live performance, the demand of which can increase for the positive externality due to the illegal download of music.File-sharing, Copyright, Sample Effect, Mp3, Concert