2006/09/30 by L. E. Ibanez, Luis E Ibáñez, A. M. Uranga +1 · 4 citations
Physics and Astronomy · Social Sciences · #Black Holes and Theoretical Physics #International Science and Diplomacy #Noncommutative and Quantum Gravity Theories #hep-ph #hep-th
paper · pdf · doi:10.1088/1126-6708/2007/03/052
published as JHEP 0703:052,2007 · 40 pages, 4 figures (v2: added references, small corrections)(v3: minor corrections)
arxiv created 2007/02/16 · openalex publication_date 2007/03/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Finding a plausible origin for right-handed neutrino Majorana masses in semirealistic compactifications of string theory remains one of the most difficult problems in string phenomenology. We argue that right-handed neutrino Majorana masses are induced by non-perturbative instanton effects in certain classes of string compactifications in which the U(1)B-L gauge boson has a Stückelberg mass. The induced operators are of the form e-UνRνR where U is a closed string modulus whose imaginary part transforms appropriately under B-L. This mass term may be quite large since this is not a gauge instanton and Re U is not directly related to SM gauge couplings. Thus the size of the induced right-handed neutrino masses could be a few orders of magnitude below the string scale, as phenomenologically required. It is also argued that this origin for neutrino masses would predict the existence of R-parity in SUSY versions of the SM. Finally we comment on other phenomenological applications of similar instanton effects, like the generation of a μ-term, or of Yukawa couplings forbidden in perturbation theory.