Radiative brane-mass terms in D>5 orbifold gauge theories

A gauge theory with gauge group G defined in D>4 space–time dimensions can be broken to a subgroup H on four-dimensional fixed point branes, when compactified on an orbifold. Mass terms for extra-dimensional components of gauge fields Ai (brane scalars) might acquire (when allowed by the brane symmetries) quadratically divergent radiative masses and thus jeopardize the stability of the four-dimensional theory. We have analyzed Z2 compactifications and identified the brane symmetries remnants of the higher-dimensional gauge invariance. No mass term is allowed for D=5 while for D>5 a tadpole ∝Fijα can appear when there are Uα(1) factors in H. A detailed calculation is done for the D=6 case and it is established that the tadpole is related, although does not coincide, with the Uα(1) anomaly induced on the brane by the bulk fermions. In particular, no tadpole is generated from gauge bosons or fermions in real representations.