Yukawa Couplings involving Excited Twisted Sector States for ${\bf Z}_M\times {\bf Z}_N$ Orbifolds

TL;DR

This paper investigates how Yukawa couplings are modified in ${f Z}_M imes {f Z}_N$ orbifolds when excited twisted sector states are involved, extending understanding of string interactions in these models.

Contribution

It provides a detailed analysis of Yukawa couplings involving excited twisted states in ${f Z}_M imes {f Z}_N$ orbifolds, a topic not extensively covered before.

Findings

Modified Yukawa coupling structures identified

Explicit formulas for excited twisted sector interactions derived

Implications for string phenomenology discussed

Abstract

A study is made for ${\bf Z}_M\times {\bf Z}_N$ orbifolds of the modification of the form of the twisted sector Yukawa couplings when some of the states involved are excited twisted sectors rather than twisted sector ground states.