Search for scalar leptons and scalar quarks at LEP

Self Cite

Abstract:The results of searches for new physics in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state are presented. The searches use an integrated luminosity of 35 pb −1 of pp collision data at a centre-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. The observed numbers of events agree with the standard model predictions, and no evidence for new physics is found. To facilitate the interpretation of our data in a broader range of new physics scenarios, information on our event selection, detector response, and efficiencies is provided.

Section: Interpretation Of Resultsmentioning

confidence: 99%

Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy at the LHC

Chatrchyan

Khachatryan

Sirunyan

et al. 2011

Self Cite

“…We, however, stress that the model is also interesting on its own right because it is gauge invariant and renormalizable. The searches at LEP have already excluded charged particles with mass below 100 GeV [89][90][91], and we focus on the region with M φ 100 GeV. We show our numerical results for the Simplified Model 1a in figure 6.…”

Section: Model 1a: Majorana Fermion Dark Mattermentioning

confidence: 99%

Simplified models of dark matter with a long-lived co-annihilation partner

Khoze

Plascencia

Sakurai

2017

We introduce a new set of simplified models to address the effects of 3-point interactions between the dark matter particle, its dark co-annihilation partner, and the Standard Model degree of freedom, which we take to be the tau lepton. The contributions from dark matter co-annihilation channels are highly relevant for a determination of the correct relic abundance. We investigate these effects as well as the discovery potential for dark matter co-annihilation partners at the LHC. A small mass splitting between the dark matter and its partner is preferred by the co-annihilation mechanism and suggests that the co-annihilation partners may be long-lived (stable or meta-stable) at collider scales. It is argued that such long-lived electrically charged particles can be looked for at the LHC in searches of anomalous charged tracks. This approach and the underlying models provide an alternative/complementarity to the mono-jet and multi-jet based dark matter searches widely used in the context of simplified models with s-channel mediators. We consider four types of simplified models with different particle spins and coupling structures. Some of these models are manifestly gauge invariant and renormalizable, others would ultimately require a UV completion. These can be realised in terms of supersymmetric models in the neutralino-stau co-annihilation regime, as well as models with extra dimensions or composite models.

“…Direct searches for superpartners at e + e − colliders, such as TRISTAN [56], and LEP [57][58][59][60], rule out such light sbottomsb 1 unless a degeneracy in the spectrum exists, in which case some of the decay products will be soft. Let us therefore consider these cases in some detail.…”

Section: Jhep05(2014)002mentioning

confidence: 99%

Constraints on a very light sbottom

Batell

Wagner

Wang

2014

Abstract:We investigate the phenomenological viability of a very light bottom squark, with a mass less than half of the Z boson mass. The decays of the Z and Higgs bosons to light sbottom pairs are, in a fairly model independent manner, strongly constrained by the precision electroweak data and Higgs signal strength measurements, respectively. These constraints are complementary to direct collider searches, which depend in detail on assumptions regarding the superpartner spectrum and decays of the sbottom. In particular, if the lightest sbottom has a mass below about 15 GeV, compatibility with these measurements is possible only in a special region of parameter space in which the couplings of the lightest sbottom to the Z and Higgs are suppressed. In this region, the second sbottom is predicted to be lighter than about 300 GeV and can also be searched for directly at the LHC. We also survey relevant collider searches for canonical scenarios with a bino, gravitino, or singlino LSP in the compressed and stealth kinematic regimes and provide suggestions to cover remaining open regions of parameter space.