Suchita Kulkarni

Anatomy of maximal stop mixing in the MSSM

A bstractA Standard Model-like Higgs near 125 GeV in the MSSM requires multi-TeV stop masses, or a near-maximal contribution to its mass from stop mixing. We investigate the maximal mixing scenario, and in particular its prospects for being realized it in potentially realistic GUT models. We work out constraints on the possible GUT-scale soft terms, which we compare with what can be obtained from some well-known mechanisms of SUSY breaking mediation. Finally, we analyze two promising scenarios in detail, namely gaugino mediation and gravity mediation with non-universal Higgs masses.

SModelS: a tool for interpreting simplified-model results from the LHC and its application to supersymmetry

We present a general procedure to decompose Beyond the Standard Model (BSM) collider signatures presenting a

Light stop in the MSSM after LHC Run 1

\mathbb {Z}_2

Yukawa-unified natural supersymmetry

Z2 symmetry into Simplified Model Spectrum (SMS) topologies. Our method provides a way to cast BSM predictions for the LHC in a model independent framework, which can be directly confronted with the relevant experimental constraints. Our concrete implementation currently focusses on supersymmetry searches with missing energy, for which a large variety of SMS results from ATLAS and CMS are available. As show-case examples we apply our procedure to two scans of the minimal supersymmetric standard model. We discuss how the SMS limits constrain various particle masses and which regions of parameter space remain unchallenged by the current SMS interpretations of the LHC results.

The flavour of natural SUSY

Abstract Light neutralino dark matter can be achieved in the Minimal Supersymmetric Standard Model if staus are rather light, with mass around 100 GeV. We perform a detailed analysis of the relevant supersymmetric parameter space, including also the possibility of light selectons and smuons, and of light higgsino- or wino-like charginos. In addition to the latest limits from direct and indirect detection of dark matter, ATLAS and CMS constraints on electroweak-inos and on sleptons are taken into account using a “simplified models” framework. Measurements of the properties of the Higgs boson at 125 GeV, which constrain amongst others the invisible decay of the Higgs boson into a pair of neutralinos, are also implemented in the analysis. We show that viable neutralino dark matter can be achieved for masses as low as 15 GeV. In this case, light charginos close to the LEP bound are required in addition to light right-chiral staus. Significant deviations are observed in the couplings of the 125 GeV Higgs boson. These constitute a promising way to probe the light neutralino dark matter scenario in the next run of the LHC.

Toward a public analysis database for LHC new physics searches using MADANALYSIS 5

A bstractThe discovery of a Higgs boson with a mass of 126 GeV at the LHC when combined with the non-observation of new physics both in direct and indirect searches imposes strong constraints on supersymmetric models and in particular on the top squark sector. The experiments for direct detection of dark matter have provided with yet more constraints on the neutralino LSP mass and its interactions. After imposing limits from the Higgs, flavour and dark matter sectors, we examine the feasibility for a light stop in the context of the pMSSM, in light of current results for stop and other SUSY searches at the LHC. We only require that the neutralino dark matter explains a fraction of the cosmologically measured dark matter abundance. We find that a stop with mass below ∼ 500 GeV is still allowed. We further study various probes of the light stop scenario that could be performed at the LHC Run-II either through direct searches for the light and heavy stop, or SUSY searches not currently available in simplified model results. Moreover we study the characteristics of heavy Higgs for the points in the parameter space allowed by all the available constraints and illustrate the region with large cross sections to fermionic or electroweakino channels. Finally we show that nearly all scenarios with a small stop-LSP mass difference will be tested by Xenon1T provided the NLSP is a chargino, thus probing a region hard to access at the LHC.

SModelS v1.0: a short user guide

A bstractA mostly right-handed sneutrino as the lightest supersymmetric particle (LSP) is an interesting dark matter candidate, leading to LHC signatures which can be quite distinct from those of the conventional neutralino LSP. Using SModelS v1.0.1 for testing the model against the limits published by ATLAS and CMS in the context of so-called Simplified Model Spectra (SMS), we investigate to what extent the supersymmetry searches at Run 1 of the LHC constrain the sneutrino-LSP scenario. Moreover, we discuss the most relevant topologies for which no SMS results are provided by the experimental collaborations but which would allow to put more stringent constraints on sneutrino LSPs. These include, for instance, the mono-lepton signature which should be particularly interesting to consider at Run 2 of the LHC.

Top Polarization in Sbottom Decays at the LHC

A bstractPrevious work on t − b − τ Yukawa-unified supersymmetry, as expected from SUSY GUT theories based on the gauge group SO(10), tended to have exceedingly large electroweak fine-tuning (EWFT). Here, we examine supersymmetric models where we simultaneously require low EWFT (“natural SUSY”) and a high degree of Yukawa coupling unification, along with a light Higgs scalar with mh ~ 125 GeV. As Yukawa unification requires large tan β ~ 50, while EWFT requires rather light third generation squarks and low μ ≈ 100 − 250 GeV, B-physics constraints from BR(B → Xsγ) and BR(Bs → μ+μ−) can be severe. We are able to find models with EWFT Δ ≲ 50 − 100 (better than 1–2% EWFT) and with Yukawa unification as low as Ryuk ~ 1.2 (20% unification). The unification is lessened to Ryuk ~ 1.3 when B-physics constraints are imposed. We present several Yukawa-unified natural SUSY (YUNS) benchmark points. LHC searches will be able to access gluinos in the lower 1 – 2 TeV portion of their predicted mass range although much of YUNS parameter space may lie beyond LHC14 reach. If heavy Higgs bosons can be accessed at a high rate, then the rare H, A → μ+μ− decay might allow a determination of tan β ~ 50 as predicted by YUNS models. Finally, the predicted light higgsinos should be accessible to a linear e+e− collider with