Catching sparks from well-forged neutralinos

Abstract

In this paper we present a new search technique for electroweakinos, the superpartners of electroweak gauge and Higgs bosons, based on final states with missing transverse energy, a photon, and a dilepton pair, + − + γ + / E T . Unlike traditional electroweakino searches, which perform best when m χ 0> m Z , our search favors nearly degenerate spectra; degenerate electroweakinos typically have a larger branching ratio to photons, and the cut m m Z effectively removes on-shell Z boson backgrounds while retaining the signal. This feature makes our technique optimal for 'well-tempered' scenarios, where the dark matter relic abundance is achieved with interelectroweakino splittings of ∼ 20 − 70 GeV. Additionally, our strategy applies to a wider range of scenarios where the lightest neutralinos are almost degenerate, but only make up a subdominant component of the dark matter -a spectrum we dub 'well-forged'. Focusing on bino-Higgsino admixtures, we present optimal cuts and expected efficiencies for several benchmark scenarios. We data for discovery, while scenarios with heavier states or larger mass splittings are harder to discriminate from the background and require more data. Unlike many searches for supersymmetry, electroweakino searches are one area where the high luminosity of the next LHC run, rather than the increased energy, is crucial for discovery.

Compressing the inert doublet model

“…For masses of the charged and neutral scalars that are relatively close to one another, 2 Note as well that the radiative decay A → H + γ is forbidden by angular momentum conservation given the point interaction of Eq. (12), in contrast to the decay χ 0 2 → χ 0 1 γ that can occur for neutralinos in supersymmetric theories [29,30].…”

Extending the reach of compressed gluinos at the LHC

“…For instance, instead of an ISR jet, an ISR photon or W/Z may be used instead for the search of a compressed sleptonneutralino or chargino-neutralino spectrum. While ideas along these lines have been explored in [31][32][33][34][35][36][37][38][39][40], we venture that a variable analogous to ρ may be constructed, involving leptons instead of jets.…”

“…[28] achieves the correct Higgs mass from radiative corrections and carefully analyzes dark matter constraints, we ignore these considerations, focusing only on our simplified spectrum and its collider strategy. Finally, specialized analyses similar in spirit to the strategy proposed here but aimed at compressed electroweakino spectra have been studied [29][30][31][32][33][34][35][36][37][38][39][40].…”

Indirect probe of electroweakly interacting particles at the high-luminosity Large Hadron Collider

“…Moreover, collider signatures are strongly affected by whether and how the EWIMP decays. The search for the EWIMP at hadron colliders becomes difficult in general if its decay products are very soft [35][36][37][38][39][40][41][42][43]. A prominent example is the direct production of the electroweakly interacting dark matter.…”