Status and prospects of the nMSSM after LHC Run-1

The new minimal supersymmetric standard model (nMSSM), a variant of the general next to minimal supersymmetric standard model (NMSSM) without $Z_3$ symmetry, features a naturally light singlino with a mass below 75 GeV. In light of the new constraints from LHC Run-1 on the Higgs couplings, sparticles searches and flavour observables, we define the parameter space of the model which is compatible with both collider and dark matter (DM) properties. Among the regions compatible with these constraints, implemented through NMSSMTools, SModelS and MadAnalysis 5, only one with a singlino lightest supersymmetric particle (LSP) with a mass around 5 GeV can explain all the DM abundance of the universe, while heavier mixed singlinos can only form one of the DM components. Typical collider signatures for each region of the parameter space are investigated. In particular, the decay of the 125 GeV Higgs into light scalars and/or pseudoscalars and the decay of the heavy Higgs into charginos and neutralinos, provide distinctive signatures of the model. Moreover, the sfermion decays usually proceed through heavier neutralinos rather than directly into the LSP, as the couplings to the singlino are suppressed. We also show that direct detection searches are complementary to collider ones, and that a future ton-scale detector could completely probe the region of parameter space with a LSP mass around 65 GeV.Comment: 33 pages, 9 figures. Version accepted for publication in JHE

Signatures of sneutrino dark matter in an extension of the CMSSM

Current data (LHC direct searches, Higgs mass, dark matter-related bounds) severely affect the constrained minimal SUSY standard model (CMSSM) with neutralinos as dark matter candidates. But the evidence for neutrino masses coming from oscillations requires extending the SM with at least right-handed neutrinos with a Dirac mass term. In turn, this implies extending the CMSSM with right-handed sneutrino superpartners, a scenario we dub $\tilde\nu$CMSSM. These additional states constitute alternative dark matter candidates of the superWIMP type, produced via the decay of the long-lived next-to-lightest SUSY particle (NLSP). Here we consider the interesting and likely case where the NLSP is a $\tilde{\tau}$: despite the modest extension with respect to the CMSSM this scenario has the distinctive signatures of heavy, stable charged particles. After taking into account the role played by neutrino mass bounds and the specific cosmological bounds from the big bang nucleosynthesis in selecting the viable parameter space, we discuss the excellent discovery prospects for this model at the future runs of the LHC. We show that it is possible to probe $\tilde{\tau}$ masses up to 600 GeV at the 14 TeV LHC with $\mathcal{L} = 1100$ fb$^{-1}$ when one considers a pair production of staus with two or more hard jets through all SUSY processes. We also show the complementary discovery prospects from a direct $\tilde{\tau}$ pair production, as well as at the new experiment MoEDAL.Comment: 31 pages, 6 figures and 5 tables; v2 : discussions and references added, conclusions unchanged. To appear in JHE

Extracting constraints from direct detection searches of supersymmetric dark matter in the light of null results from the LHC in the squark sector

The comparison of the results of direct detection of Dark Matter, obtained with various target nuclei, requires model-dependent, or even arbitrary, assumptions. Indeed, to draw conclusions either the spin-dependent (SD) or the spin-independent (SI) interaction has to be neglected. In the light of the null results from supersymmetry searches at the LHC, the squark sector is pushed to high masses. We show that for a squark sector at the TeV scale, the framework used to extract contraints from direct detection searches can be redefined as the number of free parameters is reduced. Moreover, the correlation observed between SI and SD proton cross sections constitutes a key issue for the development of the next generation of Dark Matter detectors.Comment: Figure 3 has been updated. Conclusions unchange

Apports et limitations de la stratégie du greffage pour le stockage de l’électricité

For over two decades, the electrochemical storage of electricity has embarked upon its organic revolution. Pseudo-supercapacitors, redox supercapacitors and fully organic hybrid systems have already won the scientific and industrial communities, although further efforts are needed regarding their energy density and stability in order to be integrated into structures having a long service life (aeronautic, automotive, building industry, etc.). A recent strategy consists in grafting fast redox-active small molecules to a porous carbon network. Assembling these generic modular elements to infinity yields a wide range of possible combinations and specific rules must be followed in order to ensure that this grafting is beneficial. This article presents the contributions and limitations of grafting and concludes with a novel alternative to the grafting on carbon

Catechol-Modified Activated Carbon Prepared by the Diazonium Chemistry for Application as Active Electrode Material in Electrochemical Capacitor

Activated carbon (Black Pearls 2000) modified with electroactive catechol groups was evaluated for charge storage application as active composite electrode material in an aqueous electrochemical capacitor. High surface area Black Pearls 2000 carbon, was functionalized by introduction of catechol groups by spontaneous reduction of catechol diazonium ions in situ prepared in aqueous solution from the corresponding amine. Change in the specific surface area and pore texture of the carbon following grafting was monitored by nitrogen gas adsorption measurements. The electrochemical properties and the chemical composition of the catechol-modified carbon electrodes were investigated by cyclic voltammetry. Such carbon-modified electrode combines well the faradaic capacitance, originating from the redox activity of the surface immobilized catechol groups, to the electrochemical double layer capacitance of the high surface area Black Pearls carbon. Due to the faradaic contribution, the catechol-modified electrode exhibits a higher specific capacitance (250 F/g) than pristine Carbon (150 F/g) over a potential range of -0.4 to 0.75 V in 1 M H2SO4. The stability of the modified electrode evaluated by long-time 1 charge/discharge cycling revealed a low decrease of the capacitance of the catechol-modified carbon due to the loss of the 1 catechol redox activity. Nonetheless, it was demonstrated that the benefit of redox groups persists for 10 000 constant current charge/discharge cycles

Grafting of Quinones on Carbons as Active Electrode Materials in Electrochemical Capacitors

The electrochemical performance of electrochemical capacitors can be improved with electroactive quinone molecules. Systems based on redox active electrolyte as well as physisorbed and chemically grafted molecules have been investigated. In all these cases, carbon materials were used as substrate and electrode material. This short review will mainly describe work related to these systems and materials from the authors’ laboratories. Nonetheless, some important studies from other research groups will be discussed

Rare kaon decays in SUSY with non-universal A terms

We study the rare kaon decays in the framework of general SUSY models. Unlike the results in the literature, we find the contributions from the gluino exchange to the branching ratio of $K^+\to \pi^+ \nu \bar{\nu}$ can reach the central value ($\sim 1.5 \times 10^{-10}$) of the new E787 data while the predicted value of standard model is less than $10^{-10}$. We also find that the same effects also enhance the decays of $K_{L}\to \pi^0 \nu \bar{\nu}$, $K_L\to\pi^0e^{+} e^{-}$ and $K_L\to\mu^+ \mu^-$.Comment: 9 pages, references added, revised version to appear in J. Phys.