New String Theoretic Explanation of Cosmic Inflation

Dieter Lüst, Coordinator of Research Area A (Planck Scale & Strings) is co-author of a paper that provides an updated and refined analysis on how inflation can arise from strings and branes. In a co-operation renowned string theorists and cosmologists* investigated the role of D3/D7-branes for inflationary scenarios. They were able to show how D-branes on a special manifold can cause inflation with testable predictions.

In their publication the group focused on a revision of the D3/D7-brane inflation model allowing for explicit calculations of the relevant quantum corrections. Moreover, this scenario displays phenomenological properties that are very interesting in view of some recent work on cosmic strings and the cosmic microwave background (CMB). The NASA/ESA satellite WMAP recently delivered new results on observations of the CMB, called WMAP5. Furthermore, current data of the ACBAR experiment, a multi-frequency receiver to measure slight temperature differences in the CMB, have shown that there is an excess power at some specific multipole moments. This finding might indicate an evidence for the existence of cosmic strings with tensions near the observational bounds.

The scientists studied the D3/D7-brane inflation model on a well-investigated background metric K3 X T2/Z2 such that they fit the WMAP5 observations, e.g. the observed value of the spectral index ns. Therefore, cosmic inflation might be interpreted as a string theoretical phenomenon.

* Michael Haack (LMU), Renata Kallosh (Stanford), Axel Krause (Stanford), Andrei Linde (Stanford) and Mario Zagermann (MPP)

Link to original publication

by B. Wankerl