Abstract
Neutron-antineutron oscillations are considered in the light of recently proposed particle models, which claim to resolve the neutron lifetime anomaly, indicating the existence of baryon violating $\Delta B=1$ interactions. Possible constraints are derived coming from the non-observation of neutron-antineutron oscillations, which can take place if the dark matter particle produced in neutron decay happens to be a Majorana fermion. It is shown that this can be realised in a simple MSSM extention where only the baryon number violating term $u^cd^cd^c$ is included whilst all other R-parity violating terms are prevented to avoid rapid proton decay. It is demostrated how this scenario can be implemented in a string motivated GUT broken to MSSM by fluxes.
Highlights
The nonobservation of neutrino oscillations implies κ ≪ δ, κ < 10−9δ 1⁄4 10−33, τ > 108 s.In the dark matter mediated process the value of κ1 1⁄4 3ð6.7 × 10−6Þ2 ≈ 1.3 × 10−10 was employed [5]
We have considered the possibility that the neutral dark matter particle in the putative exotic neutron decay channel is of Majorana type
In a recent paper [5] a very interesting proposal was made to resolve the long-standing discrepancy on the determination of the neutron lifetime measured in experiments involving trapped neutrons in a “bottle” and neutrons decaying in flight (“beam” experiments)
Summary
Together with protons and electrons, are the fundamental constituents of atomic matter and their properties have been studied for almost a century. Counting the emerging protons within a certain time interval, it is found that their numbers are consistent with a neutron lifetime of τn 1⁄4 888.0 Æ 2.0 sec These two measurements display a 4.0σ discrepancy which cannot be attributed to statistical uncertainties. The simplest possibility is realized with the neutron decay to a two particle final state consisting of a DM fermion χ and a monochromatic photon, n → χ þ γ Operators describing this type of decay, violate baryon number. We reconsider the interpretation of the neutron lifetime discrepancy described above, in the context of minimal supersymmetric Standard Model (MSSM) extensions and in particular SUSY and string motivated Grand Unified Theories (GUTs). For the reader’s convenience, some detailed formulas entering our calculations are given in the Appendix
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