Faculty of Science
http://hdl.handle.net/10539/20140
2017-04-21T05:52:35ZNatural supersymmetry and unification in five dimensions
http://hdl.handle.net/10539/22396
Natural supersymmetry and unification in five dimensions
Abdalgabar, A.; Cornell, A.S.; Deandrea, A.; McGarrie, M.
We explore unification and natural supersymmetry in a five dimensional extension of the standard model in which the extra dimension may be large, of the order of 1–10 TeV. Power law running generates a TeV scale At term allowing for the observed 125 GeV Higgs and allowing for stop masses below 2 TeV, compatible with a natural SUSY spectrum. We supply the full one-loop RGEs for various models and use metastability to give a prediction that the gluino mass should be lighter than 3.5 TeV for At ≥ −2.5 TeV, for such a compactification scale, with brane localised 3rd generation matter. We also discuss models in which only the 1st and 2nd generation of matter fields are located in the bulk. We also look at electroweak symmetry breaking in these models.
2016-01-01T00:00:00ZTesting R-parity with geometry
http://hdl.handle.net/10539/22395
Testing R-parity with geometry
He, Y.-H.; Jejjala, V.; Matti, C.; Nelson, B.D.
We present a complete classification of the vacuum geometries of all renormalizable superpotentials built from the fields of the electroweak sector of the MSSM. In addition to the Severi and affine Calabi-Yau varieties previously found, new vacuum manifolds are identified; we thereby investigate the geometrical implication of theories which display a manifest matter parity (or R-parity) via the distinction between leptonic and Higgs doublets, and of the lepton number assignment of the right-handed neutrino fields. We find that the traditional R-parity assignments of the MSSM more readily accommodate the neutrino see-saw mechanism with non-trivial geometry than those superpotentials that violate R-parity. However there appears to be no geometrical preference for a fundamental Higgs bilinear in the superpotential, with operators that violate lepton number, such as (Formula presented.) , generating vacuum moduli spaces equivalent to those with a fundamental bilinear.
2016-03-01T00:00:00ZLLM magnons
http://hdl.handle.net/10539/22394
LLM magnons
de Mello Koch, R.; Mathwin, C.; Van Zyl, H.J.R.
We consider excitations of LLM geometries described by coloring the LLM plane with concentric black rings. Certain closed string excitations are localized at the edges of these rings. The string theory predictions for the energies of magnon excitations of these strings depends on the radii of the edges of the rings. In this article we construct the operators dual to these closed string excitations and show how to reproduce the string theory predictions for magnon energies by computing one loop anomalous dimensions. These operators are linear combinations of restricted Schur polynomials. The distinction between what is the background and what is the excitation is accomplished in the choice of the subgroup and the representations used to construct the operator.
2016-03-01T00:00:00ZAnomalous dimensions of heavy operators from magnon energies
http://hdl.handle.net/10539/22393
Anomalous dimensions of heavy operators from magnon energies
de Mello Koch, R.; Tahiridimbisoa, N.H.; Mathwin, C.
We study spin chains with boundaries that are dual to open strings suspended between systems of giant gravitons and dual giant gravitons. Motivated by a geometrical interpretation of the central charges of su(2|2), we propose a simple and minimal all loop expression that interpolates between the anomalous dimensions computed in the gauge theory and energies computed in the dual string theory. The discussion makes use of a description in terms of magnons, generalizing results for a single maximal giant graviton. The symmetries of the problem determine the structure of the magnon boundary reflection/scattering matrix up to a phase. We compute a reflection/scattering matrix element at weak coupling and verify that it is consistent with the answer determined by symmetry. We find the reflection/scattering matrix does not satisfy the boundary Yang-Baxter equation so that the boundary condition on the open spin chain spoils integrability. We also explain the interpretation of the double coset ansatz in the magnon language.
2016-03-01T00:00:00Z