Searches in final states with two leptons plus missing transverse energy, targeting supersymmetric particles or invisible decays of the Higgs boson, were performed during Run 1 of the LHC. Recasting the results of these analyses in the context of the
Inert Doublet Model (IDM) using MadAnalysis 5, we show that they provide constraints on inert scalars that significantly extend previous limits from LEP. Moreover, these LHC constraints allow to test the IDM in the limit of very small Higgs-inert scalar coupling, where the constraints from direct detection of dark matter and the invisible Higgs width vanish.
micrOMEGAs is a code to compute dark matter observables in generic extensions of the standard model. This version of micrOMEGAs includes a generalization of the Boltzmann equations to take into account the possibility of two dark matter candidates. T
he modification of the relic density calculation to include interactions between the two DM sectors as well as semi-annihilation is presented. Both DM signals in direct and indirect detection are computed as well. An extension of the standard model with two scalar doublets and a singlet is used as an example.
In this work we present the computation of the Higgs decay into a photon and a $Z^0$ boson at one-loop level in the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM). The numerical evaluation of this decay width was performed wit
hin the framework of the SloopS code, orginally developped for the Minimal Supersymmetric Standard Model (MSSM) but which was recently extended to deal with the NMSSM. Thanks to the high level of automation of SloopS all contributions from the various sector of the NMSSM are consistently taken into account, in particular the non-diagonal chargino and sfermion contributions. We then explored the NMSSM parameter space, using HiggsBounds and HiggsSignals, to investigate to which extent these signal can be enhanced.
These lecture notes describe the micrOMEGAs code for the calculation of Dark Matter observables in extensions of the standard model.
We study a simple model that can give rise to isospin-violating interactions of Dirac fermion asymmetric dark matter to protons and neutrons through the interference of a scalar and U(1)$$ gauge boson contribution. The model can yield a large suppres
sion of the elastic scattering cross section off Xenon relative to Silicon thus reconciling CDMS-Si and LUX results while being compatible with LHC findings on the 126 GeV Higgs, electroweak precision tests and flavour constraints.
The most recent LHC data have provided a considerable improvement in the precision with which various Higgs production and decay channels have been measured. Using all available public results from ATLAS, CMS and the Tevatron, we derive for each fina
l state the combined confidence level contours for the signal strengths in the (gluon fusion + ttH associated production) versus (vector boson fusion + VH associated production) space. These combined signal strength ellipses can be used in a simple, generic way to constrain a very wide class of New Physics models in which the couplings of the Higgs boson deviate from the Standard Model prediction. Here, we use them to constrain the reduced couplings of the Higgs boson to up-quarks, down-quarks/leptons and vector boson pairs. We also consider New Physics contributions to the loop-induced gluon-gluon and photon-photon couplings of the Higgs, as well as invisible/unseen decays. Finally, we apply our fits to some simple models with an extended Higgs sector, in particular to Two-Higgs-Doublet models of Type I and Type II, the Inert Doublet model, and the Georgi-Machacek triplet Higgs model.
micrOMEGAs is a code to compute dark matter observables in generic extensions of the standard model. This new version of micrOMEGAs is a major update which includes a generalization of the Boltzmann equations to accommodate models with asymmetric dar
k matter or with semi-annihilation and a first approach to a generalization of the thermodynamics of the Universe in the relic density computation. Furthermore a switch to include virtual vector bosons in the final states in the annihilation cross sections or relic density computations is added. Effective operators to describe loop-induced couplings of Higgses to two-photons or two-gluons are introduced and reduced couplings of the Higgs are provided allowing for a direct comparison with recent LHC results. A module that computes the signature of DM captured in celestial bodies in neutrino telescopes is also provided. Moreover the direct detection module has been improved as concerns the implementation of the strange content of the nucleon. New extensions of the standard model are included in the distribution.
We analyze the extent to which the LHC and Tevatron results as of the end of 2012 constrain invisible (or undetected) decays of the Higgs boson-like state at ~ 125 GeV. To this end we perform global fits for several cases: 1) a Higgs boson with Stand
ard Model (SM) couplings but additional invisible decay modes; 2) SM couplings to fermions and vector bosons, but allowing for additional new particles modifying the effective Higgs couplings to gluons and photons; 3) no new particles in the loops but tree-level Higgs couplings to the up-quarks, down-quarks and vector bosons, relative to the SM, treated as free parameters. We find that in the three cases invisible decay rates of 23%, 61%, 88%, respectively, are consistent with current data at 95% confidence level (CL). Limiting the coupling to vector bosons, CV, to CV < 1 in case 3) reduces the allowed invisible branching ratio to 56% at 95% CL. Requiring in addition that the Higgs couplings to quarks have the same sign as in the SM, an invisible rate of up to 36% is allowed at 95% CL. We also discuss direct probes of invisible Higgs decays, as well as the interplay with dark matter searches.
Performing a fit to all publicly available data, we analyze the extent to which the latest results from the LHC and Tevatron constrain the couplings of the Higgs boson-like state at ~ 125 GeV. To this end we assume that only Standard Model (SM) parti
cles appear in the Higgs decays, but tree-level Higgs couplings to the up-quarks, down-quarks and vector bosons, relative to the SM are free parameters. We also assume that the leptonic couplings relative to the SM are the same as for the down-quark, and a custodial symmetry for the V=W,Z couplings. In the simplest approach, the effective Higgs couplings to gluons and photons are computed in terms of the previous parameters. This approach is also applied to Two-Higgs-Doublet Models of Type I and Type II. However, we also explore the possibility that the net Higgs to gluon-gluon and gamma-gamma couplings have extra loop contributions coming from Beyond-the-Standard Model physics. We find that the SM p-value ~ 0.5 is more than 2 sigma away from fits in which: a) there is some non-SM contribution to the gamma-gamma coupling of the Higgs; or b) the sign of the top quark coupling to the Higgs is opposite that of the W coupling. In both these cases p-values ~ 0.9 can be achieved. Since option b) is difficult to realize in realistic models, it would seem that new physics contributions to the effective couplings of the Higgs are preferred.
We survey the expected polarization of the top produced in the decay of a scalar top quark, $tilde t rightarrow {tilde t}chi_i^0, i =1-2$. The phenomenology is quite interesting, since the expected polarization depends both on the mixing in the stop
and neutralino sectors and on the mass differences between the stop and the neutralino. We find that a mixed stop behaves almost like a right-handed stop due to the larger hypercharge that enters the stop/top/gaugino coupling and that these polarisation effects disappear, when $m_{tilde t_1} approx m_t+m_{tildechi^0_i}$. After a discussion on the expected top polarization from the decay of a scalar top quark, we focus on the interplay of polarization and kinematics at the LHC. We discuss different probes of the top polarization in terms of lab-frame observables. We find that these observables faithfully reflect the polarization of the parent top-quark, but also have a non-trivial dependence on the kinematics of the stop production and decay process. In addition, we illustrate the effect of top polarization on the energy and transverse momentum of the decay lepton in the laboratory frame. Our results show that both spectra are softened substantially in case of a negatively polarized top, particularly for a large mass difference between the stop and the neutralino. Thus, the search strategies, and the conclusions that can be drawn from them, depends not just on the mass difference $m_{tilde t} - m_{tildechi_{i}^{0}}$ due to the usual kinematic effects but also on the effects of top polarization on the decay kinematics the extent of which depends in turn on the said mass difference.
