Light Stops from Seiberg Duality

If low-energy supersymmetry is realized in nature, a seemingly contrived hierarchy in the squark mass spectrum appears to be required. We show that composite supersymmetric theories at the bottom of the conformal window can automatically yield the spectrum that is suggested by experimental data and naturalness. With a non-tuned choice of parameters, the only superpartners below one TeV will be the partners of the Higgs, the electroweak gauge bosons, the left-handed top and bottom, and the right-handed top, which are precisely the particles needed to make weak scale supersymmetry breaking natural. In the model considered here, these correspond to composite (or partially composite) degrees of freedom via Seiberg duality, while the other MSSM fields, with their heavier superpartners, are elementary. The key observation is that at or near the edge of the conformal window, soft supersymmetry breaking scalar and gaugino masses are transmitted only to fundamental particles at leading order. With the potential that arises from the duality, a Higgs with a 125 GeV mass, with nearly SM production rates, is naturally accommodated without tuning. The lightest ordinary superpartner is either the lightest stop or the lightest neutralino. If it is the stop, it is natural for it to be almost degenerate with the top, in which case it decays to top by emitting a very soft gravitino, making it quite difficult to find this mode at the LHC and more challenging to find SUSY in general, yielding a simple realization of the stealth supersymmetry idea. We analyze four benchmark spectra in detail.Comment: 27 pages, 2 figure

Perspectives of direct Detection of supersymmetric Dark Matter in the NMSSM

In the Next-to-Minimal-Supersymmetric-Standard-Model (NMSSM) the lightest supersymmetric particle (LSP) is a candidate for the dark matter (DM) in the universe. It is a mixture from the various gauginos and Higgsinos and can be bino-, Higgsino- or singlino-dominated. Singlino-dominated LSPs can have very low cross sections below the neutrino background from coherent neutrino scattering which is limiting the sensitivity of future direct DM search experiments. However, previous studies suggested that the combination of both, the spin-dependent (SD) and spin-independent (SI) searches are sensitive in complementary regions of parameter space, so considering both searches will allow to explore practically the whole parameter space of the NMSSM. In this letter, the different scenarios are investigated with a new scanning technique, which reveals that significant regions of the NMSSM parameter space cannot be explored, even if one considers both, SI and SD, searches.Comment: 22 pages, 3 figures, this version is accepted by PLB after minor modification

Quantum interference among heavy NMSSM Higgs bosons

In the Next-to-Minimal Supersymmetric Standard Model (NMSSM), it is possible to have strong mass degeneracies between the new singlet-like scalar and the heavy doublet-like scalar, as well as between the singlet-like and doublet-like pseudoscalar Higgs states. When the difference in the masses of such states is comparable with the sum of their widths, the quantum mechanical interference between their propagators can become significant. We study these effects by taking into account the full Higgs boson propagator matrix in the calculation of the production process of $\tau^+\tau^-$ pairs in gluon fusion at the Large Hadron Collider (LHC). We find that, while these interference effects are sizeable, they are not resolvable in terms of the distributions of differential cross sections, owing to the poor detector resolution of the $\tau^+\tau^-$ invariant mass. They are, however, identifiable via the inclusive cross sections, which are subject to significant variations with respect to the standard approaches, wherein the propagating Higgs bosons are treated independently from one another. We quantify these effects for several representative benchmark points, extracted from a large set of points, obtained by numerical scanning of the NMSSM parameter space, that satisfy the most important experimental constraints currently available.Comment: 18 pages, 5 figures, 2 tables. Revised benchmark points and figures, overall results and conclusions unchanged. Version to appear in PR

Higgs bosons at 98 and 125 GeV at LEP and the LHC

We discuss NMSSM scenarios in which the lightest Higgs boson h 1 is consistent with the small LEP excess at ~ 98 GeV in e^+ e^− → Zh with h→bb and the heavier Higgs boson h 2 has the primary features of the LHC Higgs-like signals at 125 GeV, including an enhanced γγ rate. Verification or falsification of the 98 GeV h_1 may be possible at the LHC during the 14 TeV run. The detection of the other NMSSM Higgs bosons at the LHC and future colliders is also discussed, as well as dark matter properties of the scenario under consideration

Phenomenology of a Supersymmetric Model Inspired by Inflation

The current challenges in High Energy Physics and Cosmology are to build coherent particle physics models to describe the phenomenology at colliders in the laboratory and the observations in the universe. From these observations, the existence of an inflationary phase in the early universe gives guidance for particle physics models. We study a supersymmetric model which incorporates successfully inflation by a non-minimal coupling to supergravity and shows a unique collider phenomenology. Motivated by experimental data, we set a special emphasis on a new singlet-like state at 97 GeV and single out possible observables for a future linear collider that permit a distinction of the model from a similar scenario without inflation. We define a benchmark scenario that is in agreement with current collider and Dark Matter constraints, and study the influence of the non-minimal coupling on the phenomenology. Measuring the singlet-like state with high precision on the percent level seems to be promising for resolving the models, even though the Standard Model-like Higgs couplings deviate only marginally. However, a hypothetical singlet-like state with couplings of about 20% compared to a Standard Model Higgs at 97 GeV encourages further studies of such footprint scenarios of inflation.Comment: 21 pages, 10 figures; v2 matches published versio