A copy of this work was available on the public web and has been preserved in the Wayback Machine. The capture dates from 2019; you can also visit the original URL.
The file type is
In the past three years our views on how the standard model of particle physics could be embedded into string theory have dramatically changed. The heterotic string is no longer the only possibility for such an embedding and other perturbative (or non-perturbative) corners of M-theory, like Type I or Type II strings seem now possible. It has also been realized that the string scale M_s is not necessary close to the Planck scale and could be much smaller, of order the intermediate scaledoi:10.1088/0264-9381/17/5/321 fatcat:2sytb5xl2nfc3mm6qfxr6j5ucm