Universal extra dimension: Violation of Kaluza-Klein parity

The minimal universal extra dimension (mUED) model respects the Kaluza-Klein (KK) parity (-1)n, where n is the KK number. However, it is possible to have interactions located at only one of the two fixed points of the S1/Z2 orbifold. Such asymmetric interactions violate the KK parity. This kills the cold dark matter component of UED but also removes the upper bound on the inverse compactification radius, and thus nonobservation of the KK excitations even at the Large Hadron Collider does not necessarily invalidate the model. Apart from the decay of the lightest n=1 KK excitation, this leads to collider signals which are markedly different from those in the mUED scenario. The phenomenological consequences of such KK-parity violating terms are explored.