Discrete R-symmetries and anomaly universality in heterotic orbifolds

Abstract

We study discrete R-symmetries, which appear in the 4D low energy effective field theory derived from heterotic orbifold models. We derive the R-symmetries directly from the geometrical symmetries of the orbifolds. In particular, we obtain the corresponding R-charges by requiring that the couplings be invariant under these symmetries. This allows for a more general treatment than the explicit computations of correlation functions made previously by the authors, including models with discrete Wilson lines, and orbifold symmetries beyond plane-by-plane rotational invariance. The R-charges obtained in this manner differ from those derived in earlier explicit computations. We study the anomalies associated with these R-symmetries, and comment on the results.

Discrete gauge symmetry and Aharonov-Bohm radiation in string theory

“…In string theories, discrete gauge symmetries have been widely studied from various points of view [22][23][24][25][26][27][28][29][30][31][32][33][34][35]. For example, in [30], BF coupling is derived by dimensionally reducing the Chern-Simons coupling in a flux compactification, and, in [27], by dimensional reduction of the kinetic term of an RR-field in a compactification with discrete torsions.…”

Heterotic free fermionic and symmetric toroidal orbifold models

“…Moreover, the phenomenological studies of string constructions do not stop at the construction of interesting string vacua, they begin there: For example, one can look for stringy doublet-triplet splitting mechanisms [70,71] and study Yukawa coupling selection rules. In particular, for the latter, there has been quite some controversy in recent literature [72][73][74], thus, perhaps studying selection rules in the free fermionic context [75] could help settle this debate.…”

“…Whenever S is part of the set of basis vectors {B a }, we know that associated with any sector α there will be a sector α + S. Since (70) decides whether a sector corresponds to target space bosons or fermions and S involves ψ µ , it follows that if α is bosonic then α + S is fermionic and vice versa. The supersymmetry element S then leads, via (74), to the projection, that imposes the following for the signs s:…”

Flavor structure in D-brane models: Majorana neutrino masses

“…From such a viewpoint, anomalies of discrete symmetries [44,[46][47][48][49] are important because anomalous symmetries may be broken by non-perturbative effects. Even anomaly-free U(1) gauge symmetries can be broken when axions couple with U(1) gauge bosons and they become massive.…”