2019-02-17T11:28:51Z
https://digital.csic.es/dspace-oai/request
oai:digital.csic.es:10261/5526
2016-02-16T03:07:05Z
com_10261_49
com_10261_4
col_10261_175
00925njm 22002777a 4500
dc
Ibáñez, Luis E.
author
Schellekens, A. N.
author
Uranga Urteaga, Ángel M.
author
2007-04-25
Recently it has been shown that string instanton effects may give rise to neutrino Majorana masses in certain classes of semi-realistic string compactifications. In this paper we make a systematic search for supersymmetric MSSM-like Type II Gepner orientifold constructions admitting boundary states associated with instantons giving rise to neutrino Majorana masses and other L- and/or B-violating operators. We analyze the zero mode structure of D-brane instantons on general type II orientifold compactifications, and show that only instantons with O(1) symmetry can have just the two zero modes required to contribute to the 4d superpotential. We however discuss how the addition of fluxes and/or possible non-perturbative extensions of the orientifold compactifications would allow also instantons with Sp(2) and U(1) symmetries to generate such superpotentials. In the context of Gepner orientifolds with MSSM-like spectra, we find no models with O(1) instantons with just the required zero modes to generate a neutrino mass superpotential. On the other hand we find a number of models in one particular orientifold of the Gepner model (2,4,22,22) with Sp(2) instantons with a few extra uncharged non-chiral zero modes which could be easily lifted by the mentioned effects. A few more orientifold examples are also found under less stringent constraints on the zero modes. This class of Sp(2) instantons have the interesting property that R-parity conservation is automatic and the flavour structure of the neutrino Majorana mass matrices has a simple factorized form.
arXiv:0704.1079v2 [hep-th]
JHEP 06 (2007) 011
http://dx.doi.org/10.1088/1126-6708/2007/06/011
1029-8479
http://hdl.handle.net/10261/5526
10.1088/1126-6708/2007/06/011
Nonperturbative Effects
Superstring Vacua
Neutrino Physics
Intersecting branes models
High Energy Physics - Theory
High Energy Physics - Phenomenology
Instanton Induced Neutrino Majorana Masses in CFT Orientifolds with MSSM-like spectra