This is the home page of the CNCSIS/UEFISCSU project 3/3.11.2008

“Phenomenological Aspects of Heterotic String Comapctifications with Background Fluxes”

Project director: Dr. Andrei Micu

 
Description:

String Theory is one of the leading candidates for a fundamental theory. This implies that it should be possible to find the Standard model of Particle Physics within String theory. Indeed there are several examples where one comes as close as possible to the Standard model. One of the longstanding problems of string theory is that of moduli stabilisation. A lot of effort was done in the last years to find a solution to this problem. It is now more or less accepted that background fluxes constitute a key ingredient in string compactifications which may lead to moduli stabilisation. Several examples where all closed string moduli are stabilised are known, but none in truly realistic models.



The purpose of this project is to solve the issue of moduli stabilisation in a realistic model and study the influence of a matter sector on the stabilisation of the moduli. For this we choose heterotic models where the appearane of a visible/matter sector is almost atomatic. In order to stabilise moduli we shall use the "type II intuition" and turn on fluxes and use manifolds with torsion as compactification manifolds. In [1], the low energy effective action for heterotic strings compactified on certain manifolds with SU(3) structure was given for the case of "standard embedding". IN this project we shall use those results in order to study the effect of moduli stabilisation on the matter sector.

The project is supposed to run over a period of 2 years in which several objectives are proposed. These are divided into several reporting periods according to the table below.

No. Reporting period Objectives Activities Results
1 3.11.2008 -- 15.12.2008 Study supersymmetric solutions
  • Find relevant solutions
  • Study moduli stabilisation for these solutions
 arXiv: 0812.2172
2 16.12.2008 - 15.06.2009 Study of supersymmetric solutions
  • Study of the visible sector
  • Influence of moduli stabilisation on the visible sector
  
3 16.06.2009 - 15.12.2009
  • Supersymmetry breaking
  • Inflation in heterotic string compactifications
  • Effects of moduli stabilisation on the visible sector
 Heterotic Compactifications on SU(2)-structure backgrounds - published in JHEP 1001 (2010) 011

Detailed description of work done

1st reporting period

For the initial stage of the project a simple model was considered. This consists of N=1 supergravity coupled to a "visible" sector made of a E6 gauge theory with one chiral field in the 27 and one singlet field (the Kaehler modulus). The possible supersymmetric solutions with gauge group which is large enough to contain the Standard Model were classified and moduli stabilisation discussed for these cases. It has been shown that for this simple models there are no proper supersymmetric solutions. It has also been argued that the absence of solutions can be traced back to the fact that in the absence of matter fields no solutions for this model can be found either. This study helps to identify the probelms which one encounters in finding vacua of these models. In particular it is clear that one needs more complicated models which will be considered in the following stages of the project.

2nd and 3rd reporting period

In a second stage of the project a more complete analysis of the supersymmetric solutions was done. It has been argued that in a Minkowski supersymmetric E6 preserving ground state, pairs of matter fields get large masses along with pairs of moduli (both Kaehler and complex structure). Integrating out these massive fields leads to simpler models which can be analysed in detail. We have argued that such models do not have viable solutions mainly due to the fact that the superpoential is large. This prevents using the gaugino condensates to stabilise the dilaton field which is actually the only method which is available in such models. Therefore we were looking for different solutions which may allow for small values for the superpotential. If the gauge group is broken, the small values for the matter fields may lead to a small value for the superpotential. However, such solutions always have a non-vanishing flux superpotential - which is large - at least in the regime where the approximations used in order to derive these models hold.

Rapoarte anuale de autoevaluare: 2009 si 2010.

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