Flavour and CP physics in supersymmetric theories
Final Report Abstract
The LHC-experiments at CERN have started with the exploration of the tera-electron-volt-scale. With this they have entered an energy range which had not been explored before by a terrestrial experiment. The first phase culminated in the discovery of a Higgs-boson with a mass of 125 GeV. This has far reaching consequences for particle physics models beside being an extremely important discovery on its on. Supersymmetric models are among the best motived extensions of the Standard Model (SM) of particle physics. They are not only interesting for particle physics but also for cosmology as they contain for example candidates for the observed dark matter. Moreover they have the potential to explain the observed asymmetry of matter versus anti-matter in the Universe. We know that supersymmetry cannot be an exact symmetry of Nature as up to now no supersymmetric partner of the known SM-particles has been found. There are several proposals how the corresponding breaking could occur but there is no preference for any of them. For this reason one usually parametrises this breaking by so-called soft SUSY breaking terms. Several of these parameters concern the flavour sector, which is related to the mixing between different generations of matter particles. In low energy experiments we have found good agreement between the predictions of the SM and the experiment results. This implies constraints on various combination of these additional parameters. In the framework of this project we investigated to which extent it is still possible to have large flavour mixing in the so-called squark-sector and we showed that there are still large signals possible in the next run of the LHC. This does not only have consequences for the interpretation of the data: in case that indeed such a signal will be observed, it implies that flavour and the breaking of supersymmetry and are related. It would also rule out several of the existing models for supersymmetry breaking. Supersymmetric models can explain the observed neutrino masses and mixing via the breaking of a discrete symmetry called R-parity. As a consequence the lightest supersymmetric particles decays and several of its decay properties can be predicted in terms of neutrino physics. We have investigated how well these can be measured at the LHC and worked out how well the underlying parameters related to neutrino physics can be determined. The scalar potential of supersymmetric models is much more complicated than in the SM as there several scalar bosons. Therefore, it is a priori not clear, if the minimum which is required by phenomenology, is the global one. It could well be that there are additional deeper lying ones which break either charge and/or color. We have developed in the course of this project a public available software package, Vevacious, which allows for finding all extrema of the potential. It uses for this a newly developed method, the so-called homotopy continuation. With this we could show, that several parameter combinations which can successfully explain the observed mass of the Higgs-boson are actually ruled out because they would imply an unstable vacuum inconsistent with cosmological observations.
Publications
- Determining R-parity violating parameters from neutrino and LHC data, JHEP 1110 (2011) 089
F. Thomas and W. Porod
- Flavour violating gluino three-body decays at LHC, Phys. Rev. D 84 (2011) 115026
A. Bartl, H. Eberl, E. Ginina, B. Herrmann, K. Hidaka, W. Majerotto and W. Porod
- General MSSM signatures at the LHC with and without R-parity, Phys. Rev. D 86 (2012) 035021
H. K. Dreiner, F. Staub, A. Vicente and W. Porod
(See online at https://doi.org/10.1103/PhysRevD.86.035021) - Stability of the CMSSM against sfermion VEVs, JHEP 1312 (2013) 103
J. E. Camargo-Molina, B. O’Leary, W. Porod and F. Staub
(See online at https://doi.org/10.1007/JHEP12(2013)103) - Vevacious: A Tool For Finding The Global Minima Of One-Loop Effective Potentials With Many Scalars, Eur. Phys. J. C 73 (2013) 2588
J. E. Camargo-Molina, B. O’Leary, W. Porod and F. Staub
(See online at https://doi.org/10.1140/epjc/s10052-013-2588-2) - Flavor violating bosonic squark decays at LHC, Int. J. Mod. Phys. A 29 (2014) 1450035
A. Bartl, H. Eberl, E. Ginina, B. Herrmann, K. Hidaka, W. Majerotto and W. Porod
(See online at https://doi.org/10.1142/S0217751X14500353)
