Production Of Third Generation Squarks Research Articles

Searches for Direct Pair Production of Third Generation Squarks with the ATLAS Detector

This document summarises recent ATLAS results for searches for third generation squarks using 36.1 [Formula: see text] of LHC proton-proton collision data collected at [Formula: see text] TeV. Despite the absence of experimental evidence, weak scale supersymmetry remains one of the best motivated and studied Standard Model extensions. Supersymmetry can naturally solve the Standard Model hierarchy problem by preventing a large fine-tuning in the Higgs sector: a typical natural SUSY spectrum contains light third generation squarks (stops and sbottoms). Both R-Parity conserving and R-Parity violating scenarios are considered. The searches involve final states including jets, missing transverse momentum, electrons or muons. Simplified models predicting pair production of third generation squarks have been excluded at 95% CL up to about one TeV in the most favourable scenarios.

Searches for direct pair production of third generation squarks with the ATLAS detector

Naturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the third generation quarks with masses not too far from those of their Standard Model counterparts. Top or bottom squarks with masses less than or around one TeV can also give rise to direct pair production rates at the Large Hadron Collider (LHC) that can be observed in the data sample recorded by the ATLAS detector. This document presents recent ATLAS results from searches for direct top and bottom squark pair production considering both R-parity conserving and R-parity violating scenarios, using the data collected during the LHC Run 2 at a centre-of-mass energy of √s = 13 TeV.

Searches for pair production of third-generation squarks in sqrt{s}=13,text {TeV} pp collisions

Searches are presented for direct production of top or bottom squark pairs in proton–proton collisions at the CERN LHC. Two searches, based on complementary techniques, are performed in all-jet final states that are characterized by a significant imbalance in transverse momentum. An additional search requires the presence of a charged lepton isolated from other activity in the event. The data were collected in 2015 at a centre-of-mass energy of 13,text {TeV} with the CMS detector and correspond to an integrated luminosity of 2.3,text {fb}^{-1}. No statistically significant excess of events is found beyond the expected contribution from standard model processes. Exclusion limits are set in the context of simplified models of top or bottom squark pair production. Models with top and bottom squark masses up to 830 and 890,text {GeV}, respectively, are probed for light neutralinos. For models with top squark masses of 675,text {GeV}, neutralino masses up to 260,text {GeV} are excluded at 95% confidence level.

Searches for direct pair production of third generation squarks with the ATLAS detector

Naturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the third generation quarks with masses not too far from those of their Standard Model counterparts. Top or bottom squarks with masses less than a few hundred GeV can also give rise to direct pair production rates at the LHC proton-proton collisions that can be observed in the data sample recorded by the ATLAS detector. The talk presents recent ATLAS results from searches for direct stop and sbottom pair production.

Search for supersymmetry with extremely compressed spectra with the ATLAS and CMS detectors

Results of searches for supersymmetry via direct production of third-generation squarks and gluinos are reported. The analysis use 20.3 fb−1 of proton-proton collision data recorded by the ATLAS experiment and 19.5 fb−1 recorded by the CMS experiment at a centre-of-mass energy of s=8 TeV. Different signal regions based on monojet-like and c-tagged event selections optimize the sensitivity for direct top squark pair production with small mass differences between the hypothetical supersymmetric particles. In an complementary approach, the heavier top squark is searched for under the assumption that a Z boson is emitted in its decay to the lighter top squark. This strategy retains sensitivity for mass configurations where signals of direct production of the lighter top squark are hard to distinguish from the top quark pair production background. For the case of the gluino, a soft lepton analysis improves sensitivity for small mass differences between the gluino and the lightest neutralino. No significant excess above the Standard Model background expectation is observed in any of the analyses. The resulting limits significantly extend previous results at colliders.

Searches for the direct pair production of third generation squarks using the ATLAS detector

Third generation squarks are expected to have masses of < 1 TeV due to nat- uralness arguments. As such production of these squarks may be possible at the LHC. An overview of the most recent ATLAS third generation results and summary paper are presented in these proceedings. In addition to this, an overview of the outlook for such searches in Run 2 of the LHC is also presented.

Searches for direct pair production of third generation squarks with the ATLAS detector

Naturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the third generation quarks with masses not too far from those of their Standard Model counterparts. If the masses of top and bottom squarks are below 1 TeV, the direct pair production cross-section is sufficient to produce observable signatures at the ATLAS detector and to probe various theoretical scenarios with the Large Hadron Collider (LHC) data at √s = 8 TeV. The most recent ATLAS results from searches for direct stop and sbottom pair production are presented in these proceedings. No evidence of deviations from the Standard Model expectation has been observed, and the limits have been set on the masses of the top and bottom squarks.

Searches for direct pair production of third generation squarks with the ATLAS detector

Naturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the third generation quarks with masses not too far from those of their Standard Model counterparts. If the masses of top and bottom squarks are below 1 TeV, the direct pair production cross-section is sufficient to produce observable signatures at the ATLAS detector and to probe various theoretical scenarios with the Large Hadron Collider (LHC) data at √s = 8 TeV. The most recent ATLAS results from searches for direct stop and sbottom pair production are presented in these proceedings. No evidence of deviations from the Standard Model expectation has been observed, and the limits have been set on the masses of the top and bottom squarks.

New ATLAS results in SUSY searches for 3rdgeneration squarks and electroweak production

Naturalness arguments for weak-scale supersymmetry favour supersymmet- ric partners of the third generation quarks with masses close to those of their Standard Model counterparts. Real and virtual production of third generation squarks via decay of a gluino can be significant if the mass of the gluino does not exceed the TeV scale. Top or bottom squarks with masses less than a few hundred GeV can also give rise to direct pair production rates at the LHC that can be observed in the 8 TeV data sample recorded by the ATLAS detector. Moreover, many supersymmetric models feature neu- tralinos, charginos and even sleptons with masses less than a few hundred GeV so that they can be observed in the available data sample. The talk presents recent ATLAS re- sults from searches for direct stop and sbottom pair production as well as pair production of charginos, neutralinos and sleptons.

Searches for direct pair production of third generation squarks with the ATLAS detector

The most recent results of the searches for direct production of third generation squarks with the ATLAS detector are presented. All the selected analyses use 21 fb−1 of pp collisions at √s = 8 TeV and follow the assumptions of a Minimal Supersymmetric extension of the Standard Model of Particle Physics where the R-parity is conserved and the lightest supersymmetric particle (LSP) is the lightest neutralino. Naturalness considerations require that the partners of the top and bottom quarks are light (O (1 TeV)) and hence have a relatively high production cross-section at the LHC. Since no deviations from the Standard Model predictions are observed, limits are set for different mass hierarchies and mass relations between the bottom and top squarks and the lightest chargino and neutralino.

Searches for gluino-mediated production of third generation squarks with the ATLAS detector

A summary on the searches for gluino-mediated production of third generation squarks with the ATLAS detector is presented. Several scenarios in the framework of R -parity conserving minimal supersymmetric extensions of the Standard Model are considered. The results are presented based on data corresponding to an integrated luminosity of 13-21 fb−1 collected in pp collisions at √s = 8 TeV.

Searches for pair production of third generation squarks with the ATLAS detector

Naturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the third generation quarks with masses not too far from those of their Standard Model counterparts. Production of third generation squarks via decay of a gluino can be significant if the mass of the gluino does not exceed the TeV scale. Scalar top or bottom squarks with masses less than a few hundred GeV can also give rise to direct pair production rates at the LHC that can be observed in the data sample recorded by the ATLAS detector. The talk presents recent ATLAS results from searches for gluino mediated and direct stop and sbottom pair production.

Heavy-flavor tagging and the supersymmetry reach of the CERN Large Hadron Collider

The branching fraction for the decays of gluinos to third generation quarks is expected to be enhanced in classes of supersymmetric models where either third generation squarks are lighter than other squarks, or in mixed-higgsino dark matter models constructed so as to be in concordance with the measured density of cold dark matter. In such scenarios, gluino production events at the CERN Large Hadron Collider should be rich in top and bottom quark jets. Requiring b jets in addition to E miss should, therefore, enhance the supersymmetry signal relative to Standard Model backgrounds from V + jet, VV and QCD backgrounds (V=W,Z). We quantify the increase in the supersymmetry reach of the LHC from b-tagging in a variety of well-motivated models of supersymmetry. We also explore “top tagging” at the LHC. We find that while the efficiency for this turns out to be too low to give an increase in reach beyond that obtained via b-tagging, top tagging can indeed provide a confirmatory signal if gluinos are not too heavy. We also examine c jet tagging but find that it is not useful at the LHC. Finally, we explore the prospects for detecting the direct production of third generation squarks in models with an inverted squark mass hierarchy. This is signaled by b jets + E miss events being harder than in the Standard Model, but softer than those from the production of gluinos and heavier squarks. We find that while these events can be readily separated from the SM background (for third generation squark masses ∼300–500 GeV), the contamination from the much heavier gluinos and squarks remains formidable if these are also accessible.