@inbook{495ac64f0ad84d3c8383f9c548a53906,
title = "Formal Construction",
abstract = "Modular invariance of the partition function is an important guiding principle of orbifold construction. In the construction of heterotic string in Sect. 6.3.3, we have required separate modular invariance in the sixteen internal and the ten dimensional spacetime dimensions. This yielded E8 ×E8 and SO(32) heterotic strings. If we relax this to be invariance in the entire 26 dimensions, we may have a more general theory.",
author = "Choi, {Kang Sin} and Kim, {Jihn E.}",
note = "Publisher Copyright: {\textcopyright} 2020, Springer Nature Switzerland AG.",
year = "2020",
doi = "10.1007/978-3-030-54005-0_8",
language = "English",
series = "Lecture Notes in Physics",
publisher = "Springer Science and Business Media Deutschland GmbH",
pages = "215--236",
booktitle = "Lecture Notes in Physics",
}