Squark and gluino production at hadron colliders

Beenakker, W.; Höpker, R.; Spira, M.; Zerwas, P.M.

doi:10.1016/s0550-3213(97)80027-2

Cited by 758 publications

(1,008 citation statements)

References 51 publications

(64 reference statements)

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“…SUSY signal cross sections are calculated to next-toleading order (NLO) in the strong coupling constant using PROSPINO2 [49]. The inclusion of the resummation of soft gluon emission at next-to-leading-logarithmic (NLL) accuracy (NLO þ NLL) [49][50][51][52][53] is performed in the case of strong sparticle pair production.…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

“…The inclusion of the resummation of soft gluon emission at next-to-leading-logarithmic (NLL) accuracy (NLO þ NLL) [49][50][51][52][53] is performed in the case of strong sparticle pair production. For neutralino, chargino, slepton and sneutrino production, the NLO cross sections used are in agreement with the NLO þ NLL calculation within ∼2% [54][55][56].…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

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Search for supersymmetry in events with four or more leptons ins=8 TeVppcollisions with the ATLAS detector

et al. 2014

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Results from a search for supersymmetry in events with four or more leptons including electrons, muons and taus are presented. The analysis uses a data sample corresponding to 20.3 fb −1 of proton-proton collisions delivered by the Large Hadron Collider at ffiffi ffi s p ¼ 8 TeV and recorded by the ATLAS detector.Signal regions are designed to target supersymmetric scenarios that can be either enriched in or depleted of events involving the production of a Z boson. No significant deviations are observed in data from standard model predictions and results are used to set upper limits on the event yields from processes beyond the standard model. Exclusion limits at the 95% confidence level on the masses of relevant supersymmetric particles are obtained. In R-parity-violating simplified models with decays of the lightest supersymmetric particle to electrons and muons, limits of 1350 and 750 GeV are placed on gluino and chargino masses, respectively. In R-parity-conserving simplified models with heavy neutralinos decaying to a massless lightest supersymmetric particle, heavy neutralino masses up to 620 GeV are excluded. Limits are also placed on other supersymmetric scenarios.

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Section: Monte Carlo Simulationsmentioning

confidence: 99%

Section: Monte Carlo Simulationsmentioning

confidence: 99%

Search for supersymmetry in events with four or more leptons ins=8 TeVppcollisions with the ATLAS detector

et al. 2014

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“…similar to the ME cut R j,j > 0. 4. By looking at p T,j /p T,ME in generated dijet samples, we checked explicitly that out-of-cone corrections are too small to affect our study significantly.…”

Section: Mssm Searches and Jetsmentioning

confidence: 99%

Squark and gluino production with jets

2007

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We present cross section predictions for squark and gluino production at the LHC, in association with up to two additional hard jets. These cross sections can be very large in comparison to the inclusive Born rates. Because hadron collider experiments utilize hard jets in the reconstruction of cascade decays or as a way to separate squark and gluino production, the understanding of these processes is crucial. We show to what degree hard jet radiation can be described by shower algorithms and point out how tuning these showers, for example to top quark pair production, could help reduce theoretical uncertainties for new physics searches at the LHC.In the Standard Model (SM), the mechanism of the observed electroweak symmetry breaking is widely believed to involve a Higgs boson. This fundamental scalar poses a theoretical problem: the stability of its mass after the inclusion of radiative corrections. A possible solution is TeV-scale supersymmetry. The minimal supersymmetric extension of the Standard Model (MSSM) simultaneously solves several problems in high energy physics and cosmology: gauge coupling unification; radiative electroweak symmetry breaking [1]; and a stable weakly-interacting dark matter candidate [2].With the Tevatron in operation and the LHC only a few years distant, the TeV scale is rapidly coming within reach. Squark and gluino production cross sections approach O(pb) at the Tevatron and O(nb) at the LHC, for masses around the present Tevatron exclusion limits of up to 400 GeV.MSSM searches and jets: The main difference between R-parity-conserving MSSM signals and SM QCD backgrounds at a hadron collider comes from the stable lightest supersymmetric particle, an end product of all superpartner decays, which escapes the detector unobserved. Requiring a large amount of missing transverse energy is thus the first ingredient to enhance the signal. The QCDstrength production channels for squarks and gluinos are pp →gg,qq * ,qq,qg [3,4]. To a good approximation, the light-flavor MSSM squarks are mass degenerate, while the lighter of the two top squarks is often the lightest strongly-interacting MSSM particle. Searching for squarks and gluinos in an inclusive analysis the signature is jets plus / E T , possibly plus leptons. The shortest cascade of two-particle decays isg →qq andq → qχ 0 1 , where the lightest neutralinoχ 0 1 is stable. Such an inclusive search is well-suited to find MSSM-type deviations from the Standard Model. Because the gluino decay gives one more hard jet in the final state, an event's jet multiplicity provides discrimination between the relative rates of squarks and gluinos.We can also make use of longer decay chains, e.g. of the classic typeg →qq →χ 0 2 qq →llqq →χ 0 1 ℓlqq with five unknown masses. These masses can be extracted from kinematic distributions, i.e. thresholds and edges of different momentum combinations [5]. Alternative methods have been developed to improve the mass reconstruction [6] and the associated statistical and systematic errors. These measurements can in...

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“…The SUSY production cross sections for a given spectrum can be computed using Prospino 2.0 [60] at next-to-leading order in QCD. With a gluino scale mg ∼ 900 GeV and the spectra of figure 2 and 3, the dominant production cross-sections are σgg ∼ 0.53 − 0.54 pb, σqg ∼ 2.9 − 3.0 pb and σqq ∼ 1.4 − 1.5 pb.…”

Section: Collider Model and Data Generationmentioning

confidence: 99%