Peter Athron

Constrained exceptional supersymmetric standard model

We propose and study a constrained version of the exceptional supersymmetric standard model (E6SSM), which we call the cE6SSM, based on a universal high energy scalar mass m0, trilinear scalar coupling A0 and gaugino mass M1/2. We derive the renormalization group (RG) Equations for the cE6SSM, including the extra U(1)N gauge factor and the low-energy matter content involving three 27 representations of E6. We perform a numerical RG analysis for the cE6SSM, imposing the usual low-energy experimental constraints and successful electroweak symmetry breaking. Our analysis reveals that the sparticle spectrum of the cE6SSM involves a light gluino, two light neutralinos, and a light chargino. Furthermore, although the squarks, sleptons, and Z? boson are typically heavy, the exotic quarks and squarks can also be relatively light. We finally specify a set of benchmark points, which correspond to particle spectra, production modes, and decay patterns peculiar to the cE6SSM, altogether leading to spectacular new physics signals at the Large Hadron Collider.

Predictions of the constrained exceptional supersymmetric standard model

We discuss the predictions of a constrained version of the exceptional supersymmetric standard model (cE6SSM), based on a universal high energy soft scalar mass m0, soft trilinear coupling A0 and soft gaugino mass M1/2. We predict a supersymmetry (SUSY) spectrum containing a light gluino, a light wino-like neutralino and chargino pair and a light bino-like neutralino, with other sparticle masses except the lighter stop being much heavier. In addition, the cE6SSM allows the possibility of light exotic colour triplet charge 1/3 fermions and scalars, leading to early exotic physics signals at the LHC. We focus on the possibility of a Z? gauge boson with mass close to 1 TeV, and low values of (m0,M1/2), which would correspond to an LHC discovery using “first data”, and propose a set of benchmark points to illustrate this.

LHC signatures of the constrained exceptional supersymmetric standard model

We discuss two striking Large Hadron Collider (LHC) signatures of the constrained version of the exceptional supersymmetric standard model, based on a universal high-energy soft scalar mass m0, soft trilinear coupling A0 and soft gaugino mass M1/2. The first signature we discuss is that of light exotic color triplet charge 1/3 fermions, which we refer to as D-fermions. We calculate the LHC production cross section of D-fermions, and discuss their decay patterns. Secondly we discuss the E6 type U(1)N spin-1 Z? gauge boson and show how it may decay into exotic states, increasing its width and modifying the line shape of the dilepton final state. We illustrate these features using two representative exceptional supersymmetric standard model benchmark points, including an “early LHC discovery” point, giving the Feynman rules and numerical values for the relevant couplings in order to facilitate further studies

Higgs mass predictions of public NMSSM spectrum generators

The publicly available spectrum generators for the NMSSM often lead to different predictions for the mass of the standard model-like Higgs boson even if using the same renormalization scheme and two-loop accuracy. Depending on the parameter point, the differences can exceed 5 GeV, and even reach 8 GeV for moderate superparticle masses of up to 2 TeV. It is shown here that these differences can be traced back to the calculation of the running standard model parameters entering all calculations, to the approximations used in the two-loop corrections included in the different codes, and to different choices for the renormalization conditions and scales. In particular, the importance of the calculation of the top Yukawa coupling is pointed out.

Precise Higgs mass calculations in (non-)minimal supersymmetry at both high and low scales

A bstractWe present FlexibleEFTHiggs, a method for calculating the SM-like Higgs pole mass in SUSY (and even non-SUSY) models, which combines an effective field theory approach with a diagrammatic calculation. It thus achieves an all order resummation of leading logarithms together with the inclusion of all non-logarithmic 1-loop contributions. We implement this method into FlexibleSUSY and study its properties in the MSSM, NMSSM, E6SSM and MRSSM. In the MSSM, it correctly interpolates between the known results of effective field theory calculations in the literature for a high SUSY scale and fixed- order calculations in the full theory for a sub-TeV SUSY scale. We compare our MSSM results to those from public codes and identify the origin of the most significant deviations between the DR¯

Model-independent analysis of the DAMPE excess

\overline{\mathrm{DR}}

GAMBIT: the global and modular beyond-the-standard-model inference tool

programs. We then perform a similar comparison in the remaining three non-minimal models. For all four models we estimate the theoretical uncertainty of Flex- ibleEFTHiggs and the fixed-order DR¯