Narrow Results

We present the implementation, in the MadAnalysis 5 framework, of the ATLAS-SUSY-2018-31 search for new physics, and document the validation of this implementation. This analysis targets, with 139 fb${}^{-1}$ of proton–proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector between 2015 and 2018, the production of a pair of supersymmetric bottom squarks when they further decay through a cascade decay involving the second lightest neutralino and a Standard Model Higgs boson. The validation of our work is based on three benchmark scenarios targeting different kinematic configurations. The first of them considers a new physics spectrum leading to the presence of high-$p_T$$b$-jets originating from sbottom decays, whereas the last two, that differ by the neutralino mass spectrum, are dedicated to the compressed regime and thus yield the presence of soft $b$-jets in the final state. We obtain an agreement between the MadAnalysis 5 predictions and the official ATLAS results at the level of 20–30%, the largest discrepancies being related to cases exhibiting a poor Monte Carlo numerical precision at the level of the official ATLAS results.

We analyze the Next-to-minimal supersymmetric Standard Model with Grand unification boundary conditions under current theoretical and experimental constraints. We compute the mass spectrum of the model and focus on the three lightest particles in the Higgs sector (two CP-even scalars, $h_1$, $h_2$ and one CP-odd, $a_1$). The reduced couplings of such particles, singlet-doublet components, their branching ratios to bosons and reduced cross-section to photons and massive gauge bosons via gluon fusion are thoroughly and systematically scrutinized. Our analysis is focused on the parameter space where the singlet-doublet coupling $\lambda$ is as large as possible (keeping the perturbativity bound intact) and the ratio between the vacuum expectation values of the up-type and down-type Higgses $(\mathrm{\text{tan}}\beta )$ is as small as possible, which is the region representing the most natural case of the NMSSM. We show the impact of recent constraints from the LHC on the SM-Higgs couplings to bosons and fermions on the parameter space of the model and the consequent implications on the Higgs sector. The results show that while the model is still able to account for current data, and provide an opportunity for discovery of extended Higgs sectors, recent LHC Higgs couplings constraints rule-out parts of the parameter space where $h_2$ (non-SM-like) and $a_1$ are non-singlet with masses below 400 GeV.

In this talk (talk given at the International Conference on Massive Neutrinos, Singapore, 9-13 February 2015), I describe the general characteristics of radiative neutrino mass models that can be probed at the LHC. I then cover the specific constraints on a new, explicit model of this type.

Radiative neutrino mass models and the seesaw models are viewed from the unifying framework of standard model effective operators that explicitly violate lepton number by two units $(\mathrm{\Delta }L=2)$. After some comments on naturalness and leptogenesis in the minimal type 1 seesaw model, a full list of minimal renormalisable models that produce mass dimension-7, $\mathrm{\Delta }L=2$ operators at low energies is presented. By way of example, phenomenological bounds from Run 1 LHC and lepton flavour violation data are then placed on one of these models. A possible connection between radiative neutrino mass models and the current flavour anomalies in $b\to c$ and $b\to s$ transitions is then described.

Radiative neutrino mass models and the seesaw models are viewed from the unifying framework of standard model effective operators that explicitly violate lepton number by two units (ΔL = 2). After some comments on naturalness and leptogenesis in the minimal type 1 seesaw model, a full list of minimal renormalisable models that produce mass dimension-7, ΔL = 2 operators at low energies is presented. By way of example, phenomenological bounds from Run 1 LHC and lepton flavour violation data are then placed on one of these models. A possible connection between radiative neutrino mass models and the current flavour anomalies in b → c and b → s transitions is then described.

In this talk, I describe the general characteristics of radiative neutrino mass models that can be probed at the LHC. I then cover the specific constraints on a new, explicit model of this type.