Search for squarks and gluinos in final states with hadronically decaying τ -leptons, jets, and missing transverse momentum using p p collisions at s = 13 TeV with the ATLAS detector
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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Search for pair production of Higgsinos in final states with at least three b -tagged jets in s = 13 TeV p p collisions using the ATLAS detector
Not Available
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Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector
A search for pair production of up-type vector-like quarks ( T ) with a significant branching ratio into a top quark and either a Standard Model Higgs boson or a Z boson is presented. The same analysis is also used to search for four-top-quark production in several new physics scenarios. The search is based on a dataset of pp collisions at $\sqrt{s}$ =13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb -1 . Data are analysed in the lepton+jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets, as well as the jets + E T miss final state, characterised by multiple jets and large missing transverse momentum. The search exploits the high multiplicity of jets identified as originating from b -quarks, and the presence of boosted, hadronically decaying top quarks and Higgs bosons reconstructed as large-radius jets, characteristic of signal events. No significant excess above the Standard Model expectation is observed, and 95% CL upper limits are set on the production cross sections for the different signal processes considered. These cross-section limits are used to derive lower limits on the mass of a vector-like T quark under several branching ratio hypotheses assuming contributions from T → W b , Zt , Ht decays. The 95% CL observed lower limits on the T quark mass range between 0 . 99 TeV and 1 . 43 TeV for all possible values of the branching ratios into the three decay modes considered, significantly extending the reach beyond that of previous searches. Additionally, upper limits on anomalous four-top-quark production are set in the context of an effective field theory model, as well as in an universal extra dimensions model.
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Search for pair production of heavy vector-like quarks decaying into high-p T W bosons and top quarks in the lepton-plus-jets final state in pp collisions at $ \sqrt{s}=13$ TeV with the ATLAS detector
A search is presented for the pair production of heavy vector-like B quarks, primarily targeting B quark decays into a W boson and a top quark. The search is based on 36.1 fb -1 of pp collisions at s√=13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Data are analysed in the lepton-plus-jets final state, characterised by a high-transverse-momentum isolated electron or muon, large missing transverse momentum, and multiple jets, of which at least one is b-tagged. No significant deviation from the Standard Model expectation is observed. The 95% confidence level lower limit on the B mass is 1350 GeV assuming a 100% branching ratio to Wt. In the SU(2) singlet scenario, the lower mass limit is 1170 GeV. The 100% branching ratio limits are found to be also applicable to heavy vector-like X production, with charge +5/3, that decay into Wt. In conclusion, this search is also sensitive to a heavy vector-like B quark decaying into other final states (Zb and Hb) and thus mass limits on B production are set as a function of the decay branching ratios.
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Search for pair production of Higgs bosons in the b b ¯ b b ¯ final state using proton-proton collisions at s = 13 TeV with the ATLAS detector with the ATLAS detector
A search for Higgs-boson pair production in the b b ¯ b b ¯ final state using proton-proton collisions at s = 13 TeV final state is carried out with 3.2 fb -1 of proton-proton collision data collected at √s=13 TeV with the ATLAS detector. The data are consistent with the estimated background and are used to set upper limits on the production cross section of Higgs-boson pairs times branching ratio to b b ¯ b b ¯ final state using proton-proton collisions at s = 13 TeV for both nonresonant and resonant production. In the case of resonant production of Kaluza-Klein gravitons within the Randall-Sundrum model, upper limits in the 24 to 91 fb range are obtained for masses between 600 and 3000 GeV, at the 95% confidence level. The production cross section times branching ratio for nonresonant Higgs-boson pairs is also constrained to be less than 1.22 pb, at the 95% confidence level.
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Measurement of top quark polarization in t t ¯ lepton + jets final states
We present a measurement of top quark polarization in t ¯ t pair production in p ¯ p collisions at √ s = 1.96 TeV using data corresponding to 9.7 fb -1 of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. We consider final states containing a lepton and at least three jets. The polarization is measured through the distribution of lepton angles along three axes: the beam axis, the helicity axis, and the transverse axis normal to the t ¯ t production plane. This is the first measurement of top quark polarization at the Tevatron using lepton + jet final states and the first measurement of the transverse polarization in t ¯ t production. The observed distributions are consistent with standard model predictions of nearly no polarization.
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Search for D 0 decays to invisible final states at Belle
Here, we report the result from the first search for D 0 decays to invisible final states. The analysis is performed on a data sample of 924 fb - 1 collected at and near the Υ ( 4 S ) and Υ ( 5 S ) resonances with the Belle detector at the KEKB asymmetric-energy e + e - collider. The absolute branching fraction is confirmed using an inclusive D 0 sample, obtained by fully reconstructing the rest of the particle system including the other charmed particle. No significant signal yield is observed and an upper limit of 9.4 × 10 - 5 is set on the branching fraction of D 0 to invisible final states at 90% confidence level.
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Search for strong gravity in multijet final states produced in pp collisions at s = 13 $$ \sqrt{s}=13 $$ TeV using the ATLAS detector at the LHC
N/A
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A search for top squarks with R-parity-violating decays to all-hadronic final states with the ATLAS detector in $ \sqrt{s}=8 $ TeV proton-proton collisions
A search for the pair production of top squarks, each with R -parity-violating decays into two Standard Model quarks, is performed using 17.4 fb -1 of √s=8 TeV proton-proton collision data recorded by the ATLAS experiment at the LHC. Each top squark is assumed to decay to a b- and an s-quark, leading to four quarks in the final state. Background discrimination is achieved with the use of b-tagging and selections on the mass and substructure of large-radius jets, providing sensitivity to top squark masses as low as 100 GeV. Finally, no evidence of an excess beyond the Standard Model background prediction is observed and top squarks decaying to $\overline{b}$$\overline{s}$ are excluded for top squark masses in the range 100 ≤ m $\overline{t}$ ≤ 315 GeV at 95% confidence level.
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Erratum to: Search for heavy resonances decaying into a $W$ or $Z$ boson and a Higgs boson in final states with leptons and $b$-jets in 36 fb –1 of $ \sqrt{s}=13 $ TeV $pp$ collisions with the ATLAS detector
The exclusion limits for the gluon-gluon fusion production of an $A$ boson reported in the conclusions did not correspond to the exclusion plots shown in figure 6a.
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Search for high-mass new phenomena in the dilepton final state using proton–proton collisions at s = 13 TeV with the ATLAS detector
A search is conducted for both resonant and non-resonant high-mass new phenomena in dielectron and dimuon final states. The search uses 3.2 fb-1of proton–proton collision data, collected at √s = 13 TeV by the ATLAS experiment at the LHC in 2015. The dilepton invariant mass is used as the discriminating variable. No significant deviation from the Standard Model prediction is observed; therefore limits are set on the signal model parameters of interest at 95% credibility level. Upper limits are set on the cross-section times branching ratio for resonances decaying to dileptons, and the limits are converted into lower limits on the resonance mass, ranging between 2.74 TeV and 3.36 TeV, depending on the model. Lower limits on the ℓℓqq contact interaction scale are set between 16.7 TeV and 25.2 TeV, also depending on the model.
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Search for vector-boson resonances decaying to a top quark and bottom quark in the lepton plus jets final state in pp collisions at s = 13 TeV with the ATLAS detector
A search for new charged massive gauge bosons, is performed with the ATLAS detector at the LHC. Data were collected in proton–proton collisions at a center-of-mass energy of $\sqrt{s} = 13$ TeV and correspond to an integrated luminosity of . This analysis searches for W' bosons in the W' → t$\bar{b}$ ecay channel in final states with an electron or muon plus jets. The search covers resonance masses between 0.5 and 5.0 TeV and considers right-handed W' bosons. No significant deviation from the Standard Model (SM) expectation is observed and upper limits are set on the W' → t$\bar{b}$ cross section times branching ratio and the W' boson effective couplings as a function of the W' boson mass. For right-handed W' bosons with coupling to the SM particles equal to the SM weak coupling constant, masses below 3.15 TeV are excluded at the 95% confidence level. This search is also combined with a previously published ATLAS result for W' → t$\bar{b}$ in the fully hadronic final state. Using the combined searches, right-handed bosons with masses below 3.25 TeV are excluded at the 95% confidence level.
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Search for chargino and neutralino production in final states with a Higgs boson and missing transverse momentum at s√=13 TeV with the ATLAS detector
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for vectorlike leptons in multilepton final states in proton-proton collisions at s = 13 TeV
A search for vector-like leptons in multilepton final states is presented. The data sample corresponds to an integrated luminosity of 77.4 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2016 and 2017. Events are categorized by the multiplicity of electrons, muons, and hadronically decaying $\tau$ leptons. The missing transverse momentum and the scalar sum of the lepton transverse momenta are used to distinguish the signal from background. The observed results are consistent with the expectations from the standard model hypothesis. The existence of a vector-like lepton doublet, coupling to the third generation standard model leptons in the mass range of 120-790 GeV, is excluded at 95% confidence level. These are the most stringent limits yet on the production of a vector-like lepton doublet, coupling to the third generation standard model leptons.
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Search for pair production of vectorlike quarks in the fully hadronic final state
Not Available
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Measurement of the top quark Yukawa coupling from t t ¯ kinematic distributions in the lepton + jets final state in proton-proton collisions at s = 13 TeV
Not Available
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Studies of charmed strange baryons in the Λ D final state at Belle
In this report, we discuss the discovery of Ξ c ( 3055 ) 0 , observed by its decay into the final-state Λ D 0 , and present the first observation and evidence of the decays of Ξ c ( 3055 ) + and Ξ c ( 3080 ) + into Λ D + . Furthermore, we perform a combined analysis of the Λ D + with the Σ c + + K - and Σ c * + + K - decay modes to measure the ratios of branching fractions, masses and widths with improved accuracy. We measure the ratios of branching fractions B ( Ξ c ( 3055 ) + → Λ D + ) / B ( Ξ c ( 3055 ) + → Σ c + + K - ) = 5.09 ± 1.01 ± 0.76 , B ( Ξ c ( 3080 ) + → Λ D + ) / B ( Ξ c ( 3080 ) + → Σ c + + K - ) = 1.29 ± 0.30 ± 0.15 , and B ( Ξ c ( 3080 ) + → Σ c * + + K - ) / B ( Ξ c ( 3080 ) + → Σ c + + K - ) = 1.07 ± 0.27 ± 0.04 , where the uncertainties are statistical and systematic. The analysis is performed using a 980 fb - 1 data sample collected with the Belle detector at the KEKB asymmetric-energy e + e - collider.
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Measurement of the t t ¯ production cross section in the τ + jets final state in p p collisions at s = 8 TeV using the ATLAS detector
A measurement of the inclusive p p → t $\bar{t}$ + X production cross section in the τ + jets final state using only the hadronic decays of the τ lepton is presented. The measurement is performed using 20.2 fb -1 of proton-proton collision data recorded at a center-of-mass energy of √ s = 8 TeV with the ATLAS detector at the Large Hadron Collider. The cross section is measured via a counting experiment by imposing a set of selection criteria on the identification and kinematic variables of the reconstructed particles and jets, and on event kinematic variables and characteristics. The production cross section is measured to be σ t $\bar{t}$ = 239 ± 29 pb , which is in agreement with the measurements in other final states and the theoretical predictions at this center-of-mass energy.
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