Kaluza-Klein masses in nonprime orbifolds: Z(12-I) compactification and threshold correction

Understand

Analyzing the one-loop partition function, we discuss possible Kaluza-Klein (KK) states in the orbifold compactification of the heterotic string theory, toward the application to the threshold correction.

• The KK massive states associated with (relatively) large extra dimensions can arise only in non-prime orbifolds.
• The GSO projection condition by a shift vector $V^I$ is somewhat relaxed above the compactification scale 1/R.
• We also present the other condition on Wilson line $W$, $P\cdot W={\rm integer}$.