Search for the electroweak production of supersymmetric particles ins=8  TeVppcollisions with the ATLAS detector

Abstract

The ATLAS experiment has performed extensive searches for the electroweak production of charginos, neutralinos, and staus. This article summarizes and extends the search for electroweak supersymmetry with new analyses targeting scenarios not covered by previously published searches. New searches use vectorboson fusion production, initial-state radiation jets, and low-momentum lepton final states, as well as multivariate analysis techniques to improve the sensitivity to scenarios with small mass splittings and lowproduction cross sections. Results are based on 20 fb −1 of proton-proton collision data at ffiffi ffi s p ¼ 8 TeV recorded with the ATLAS experiment at the Large Hadron Collider. No significant excess beyond Standard Model expectations is observed. The new and existing searches are combined and interpreted in terms of 95% confidence-level exclusion limits in simplified models, where a single production process and decay mode is assumed, as well as within phenomenological supersymmetric models.

Impact of jet veto resummation on slepton searches

“…However, this does not include the uncertainty induced by the jet veto, which could easily be as large as our NLL uncertainty, since the perturbative precision of parton showers to model the jet veto is at best NLL. 8 At NLL the exclusion limits are noticeably weaker and would go down to ∼ 270 GeV for left-handed sleptons and ∼ 210 GeV for righthanded sleptons. Even our NLL +NLO results (without including PDF+α s uncertainties) yield somewhat larger uncertainties.…”

“…This amounts to placing a veto on additional jets above a certain transverse momentum p cut T arising from QCD initial-state or final-state radiation. Typical examples are supersymmetry (SUSY) searches for third generation squarks requiring two signal jets and vetoing a third jet [1][2][3], or electroweakino/slepton searches usually requiring 0 signal jets [4][5][6][7][8]. Jet vetoes are also applied in other BSM searches, including anomalous triple-gauge couplings [9], unparticles [10], large extra dimensions and dark matter candidates in mono-photon, mono-Z and mono-jet events [11][12][13].…”

“…7 We simply exclude the regions where the calculated 0-jet cross section is larger than the upper limit, σ 95 0,vis , without calculating a CLs value. 8 Note that the Monte Carlo predictions are reweighted to the total NLO cross section. This is equivalent to rescaling the NLL green band in figure 6 to match the NLO result at large p cut T 2m˜ and does not improve the resummation precision.…”

Sbottoms of natural NMSSM at the LHC

“…The latter is constrained by LHC analyses involving the chargino-LSP system when the chargino decays 100% of the times to W -LSP, which is the case in the NMSSM scenario we are discussing. References [49,50] indicate that under such a situation chargino mass as low as 200 GeV is allowed 3 for a LSP mass around 100 GeV.…”

Natural NMSSM with a light Singlet Higgs and Singlino LSP

“…In the neutralino and chargino sector, both ATLAS and CMS have studied χ 2 χ + 1 production [64][65][66]. For example, the searches which assume decays to sleptons or to bosons also assume that m χ 60 , in which case it is unlikely that the exclusion can apply.…”