Siegfried Bethke

Max Planck Institute for Physics | MPP · Department of Experimental Physics

This document collects a written summary of all contributions presented at the workshop "$\alpha_s$(2019): Precision measurements of the strong coupling" held at ECT* (Trento) in Feb. 11--15, 2019. The workshop explored in depth the latest developments on the determination of the QCD coupling $\alpha_s$ from the key categories where high precision...

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,873 new measurements from 758 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as super...

A search for W′-boson production in the W′→tb¯→qq¯′bb¯ decay channel is presented using 36.1fb⁻¹ of 13 TeV proton–proton collision data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search is interpreted in terms of both a left-handed and a right-handed chiral W′ boson within the mass range 1–5 TeV. Identificati...

This paper presents a search for direct electroweak gaugino or gluino pair production with a chargino nearly mass-degenerate with a stable neutralino. It is based on an integrated luminosity of 36.1 fb−1 of pp collisions at \( \sqrt{s}=13 \) TeV collected by the ATLAS experiment at the LHC. The final state of interest is a disappearing track accomp...

The inclusive and fiducial \(t\bar{t}\) production cross-sections are measured in the lepton+jets channel using \(20.2~\hbox {fb}^{-1}\) of proton–proton collision data at a centre-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. Major systematic uncertainties due to the modelling of the jet energy scale and b-tagging efficiency...

This Letter presents a search for exotic decays of the Higgs boson to a pair of new (pseudo)scalar particles, H→aa, where the a particle has a mass in the range 20–60 GeV, and where one of the a bosons decays into a pair of photons and the other to a pair of gluons. The search is performed in event samples enhanced in vector-boson fusion Higgs boso...

A direct search for the standard model Higgs boson decaying to a pair of charm quarks is presented. Associated production of the Higgs and Z bosons, in the decay mode ZH→ℓ+ℓ−cc¯ is studied. A data set with an integrated luminosity of 36.1 fb−1 of pp collisions at s=13TeV recorded by the ATLAS experiment at the LHC is used. The H→cc¯ signature is id...

A search is presented for photonic signatures, motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of proton-proton collision data at s=13 TeV corresponding to an integrated luminosity of 36.1 fb−1 recorded by the ATLAS detector at the LHC, and it explores models dominated by both strong and electroweak p...

A search for the narrow structure, X(5568), reported by the D0 Collaboration in the decay sequence X→Bs0π±, Bs0→J/ψϕ, is presented. The analysis is based on a data sample recorded with the ATLAS detector at the LHC corresponding to 4.9 fb−1 of pp collisions at 7 TeV and 19.5 fb−1 at 8 TeV. No significant signal was found. Upper limits on the number...

This paper presents a measurement of the W boson production cross section and the W +/W − cross-section ratio, both in association with jets, in proton-proton collisions at \( \sqrt{s}=8 \) TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum...

A search for the standard model Higgs boson produced in association with a top-quark pair, tt¯H, is presented. The analysis uses 36.1 fb−1 of pp collision data at s=13 TeV collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search targets the H→bb¯ decay mode. The selected events contain either one or two electrons...

A search for high-mass resonances decaying to τν using proton-proton collisions at s=13 TeV produced by the Large Hadron Collider is presented. Only τ-lepton decays with hadrons in the final state are considered. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 36.1 fb−1. No statistically significant exce...

A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at s=13TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state XH...

A search for the associated production of the Higgs boson with a top quark pair (tt¯H) is reported. The search is performed in multilepton final states using a data set corresponding to an integrated luminosity of 36.1 fb−1 of proton-proton collision data recorded by the ATLAS experiment at a center-of-mass energy s=13 TeV at the Large Hadron Colli...

A search for heavy resonances decaying into a pair of \(Z\) bosons leading to \(\ell ^+\ell ^-\ell ^+\ell ^-\) and \(\ell ^+\ell ^-\nu \bar{\nu }\) final states, where \(\ell \) stands for either an electron or a muon, is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 \(\text {TeV}\) corresponding to an int...

This paper presents combinations of inclusive and differential measurements of the charge asymmetry (AC) in top quark pair \( \left(\mathrm{t}\overline{\mathrm{t}}\right) \) events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. The data corres...

A search for long-lived, massive particles predicted by many theories beyond the Standard Model is presented. The search targets final states with large missing transverse momentum and at least one high-mass displaced vertex with five or more tracks, and uses 32.8 fb−1 of s=13 TeVpp collision data collected by the ATLAS detector at the LHC. The obs...

A search for electroweak production of supersymmetric particles in scenarios with compressed mass spectra in final states with two low-momentum leptons and missing transverse momentum is presented. This search uses proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015–2016, corresponding to 36.1 fb−1 of in...

A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb−1 of √s = 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the background prediction is observed. Results are interpreted in a SUSY simplified model wher...

A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented. The search uses a proton–proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to 36.1 fb−1 of integrated luminosity recorded in 2015 and 2016 by the ATLAS detector at the LHC. This...

The differential cross-section for the production of a W boson in association with a top quark is measured for several particle-level observables. The measurements are performed using 36.1 fb - 1 of pp collision data collected with the ATLAS detector at the LHC in 2015 and 2016. Differential cross-sections are measured in a fiducial phase spac...

This paper reports searches for heavy resonances decaying into ZZ or ZW using data from proton-proton collisions at a centre-of-mass energy of \( \sqrt{s}=13 \) TeV. The data, corresponding to an integrated luminosity of 36.1 fb−1, were recorded with the ATLAS detector in 2015 and 2016 at the Large Hadron Collider. The searches are performed in fin...

A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented. The search uses a proton–proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to 36.1 \(\text {fb}^{-1}\) of integrated luminosity recorded in 2015 and 2016 by the ATLAS detector at...

A search is conducted for new resonances decaying into a W W or W Z boson pair, where one W boson decays leptonically and the other W or Z boson decays hadronically. It is based on proton-proton collision data with an integrated luminosity of 36.1 fb−1 collected with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of \( \...

The production of a top quark in association with a Z boson is investigated. The proton–proton collision data collected by the ATLAS experiment at the LHC in 2015 and 2016 at a centre-of-mass energy of s=13TeV are used, corresponding to an integrated luminosity of 36.1fb−1. Events containing three identified leptons (electrons and/or muons) and two...

The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb⁻¹. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti-kt algorith...

The coupling properties of the Higgs boson are studied in the four-lepton (e, μ) decay channel using 36.1 fb−1 of pp collision data from the LHC at a centre-of-mass energy of 13 TeV collected by the ATLAS detector. Cross sections are measured for the main production modes in several exclusive regions of the Higgs boson production phase space and ar...

A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb\(^{-1}\) of \(\sqrt{s}\) = 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the background prediction is observed. Results are interpreted in a SUSY simp...

A measurement of the production of three isolated photons in proton–proton collisions at a centre-of-mass energy s=8 TeV is reported. The results are based on an integrated luminosity of 20.2 fb −1 collected with the ATLAS detector at the LHC. The differential cross sections are measured as functions of the transverse energy of each photon, the dif...

A search is conducted for new resonances decaying into a W or Z boson and a 125 GeV Higgs boson in the \( \nu \overline{\nu}b\overline{b} \), \( {\ell}^{\pm}\nu b\overline{b} \), and \( {\ell}^{+}{\ell}^{-}b\overline{b} \) final states, where ℓ± = e± or μ±, in pp collisions at \( \sqrt{s}=13 \) TeV. The data used correspond to a total integrated lu...

The modification of the production of J/ ψ, ψ(2 S) , and Υ(nS) (n= 1 , 2 , 3) in p+Pb collisions with respect to their production in pp collisions has been studied. The p+Pb and pp datasets used in this paper correspond to integrated luminosities of 28nb-1 and 25pb-1 respectively, collected in 2013 and 2015 by the ATLAS detector at the LHC, both at...

A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of 36.1 fb−1 , recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. No...

This paper presents a direct measurement of the decay width of the top quark using tt¯ events in the lepton+jets final state. The data sample was collected by the ATLAS detector at the LHC in proton–proton collisions at a centre-of-mass energy of 8 TeV and corresponds to an integrated luminosity of 20.2 fb −1 . The decay width of the top quark is m...

A detailed study of multiparticle azimuthal correlations is presented using pp data at s=5.02 and 13 TeV, and p+Pb data at sNN=5.02 TeV, recorded with the ATLAS detector at the CERN Large Hadron Collider. The azimuthal correlations are probed using four-particle cumulants cn{4} and flow coefficients vn{4}=(−cn{4})1/4 for n=2 and 3, with the goal of...

Measurements of ZZ production in the ℓ+ℓ−ℓ′+ℓ′− channel in proton–proton collisions at 13 TeV center-of-mass energy at the Large Hadron Collider are presented. The data correspond to 36.1 fb−1 of collisions collected by the ATLAS experiment in 2015 and 2016. Here ℓ and ℓ′ stand for electrons or muons. Integrated and differential ZZ→ℓ+ℓ−ℓ′+ℓ′− cross...

A search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an R-parity-violating coupling to a final state with two leptons and two jets, at least one of which is identified as a b-jet. The data set corresponds to an integrated luminosity of 36.1 fb−1 of proton-proton collision...

A measurement of the mass of the W boson is presented based on proton–proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb−14.6 fb−1 of integrated luminosity. The selected data sample consists of 7.8×1067.8×106 candidates in the W→μνW→μν channel and 5.9×1065.9×106...

A measurement of the mass of the W boson is presented based on proton–proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb−1 of integrated luminosity. The selected data sample consists of 7.8×106 candidates in the W→μν channel and 5.9×106 candidates in the W→eν ch...

A search is performed for new phenomena in events having a photon with high transverse momentum and a jet collected in 36.7 fb−1 of proton–proton collisions at a centre-of-mass energy of s√ = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The invariant mass distribution of the leading photon and jet is examined to look for th...

A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb⁻¹ of proton–proton collision data at s=13TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state XH...

A search is performed for new phenomena in events having a photon with high transverse momentum and a jet collected in 36.7 fb - 1 of proton-proton collisions at a centre-of-mass energy of s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The invariant mass distribution of the leading photon and jet is examined to lo...

A measurement of the mass of the W boson is presented based on proton–proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to \(4.6~\hbox {fb}^{-1}\) of integrated luminosity. The selected data sample consists of \(7.8\times 10^6\) candidates in the \(W\rightarrow \mu \nu \...

This paper presents a direct measurement of the decay width of the top quark using \(t\bar{t}\) events in the lepton+jets final state. The data sample was collected by the ATLAS detector at the LHC in proton–proton collisions at a centre-of-mass energy of 8 TeV and corresponds to an integrated luminosity of 20.2 fb\(^{-1}\). The decay width of the...

Measurements of longitudinal flow correlations are presented for charged particles in the pseudorapidity range \(|\eta |<2.4\) using 7 and 470 \(\upmu \hbox {b}^{-1}\) of Pb+Pb collisions at \(\sqrt{s_{\text {NN}}}=2.76\) and 5.02 TeV, respectively, recorded by the ATLAS detector at the LHC. It is found that the correlation between the harmonic flo...

A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of 36.1 fb - 1 , recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 Te...

The inclusive cross-section for the associated production of a W boson and top quark is measured using data from proton-proton collisions at \( \sqrt{s}=13 \) TeV. The dataset corresponds to an integrated luminosity of 3.2 fb−1, and was collected in 2015 by the ATLAS detector at the Large Hadron Collider at CERN. Events are selected requiring two o...

A search for heavy neutral Higgs bosons and Z′ bosons is performed using a data sample corresponding to an integrated luminosity of 36.1 fb−1 from proton-proton collisions at \( \sqrt{s}=13 \) TeV recorded by the ATLAS detector at the LHC during 2015 and 2016. The heavy resonance is assumed to decay to τ +τ − with at least one tau lepton decaying t...

A search for weakly interacting massive dark-matter particles produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse momentum are considered. The analysis uses 36.1fb−136.1fb−1 of proton–proton collision data recorded by the ATLAS experiment at s√=13s=13 TeV in 2015 and...

A search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a leptonically decaying Z boson in proton–proton collisions at s=13 TeV is presented. This search uses 36.1 fb −1 of data collected by the ATLAS experiment at the Large Hadron Collider. No significant deviation from the expectation of the Standard...

A search for weakly interacting massive dark-matter particles produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse momentum are considered. The analysis uses \(36.1 \; \mathrm {fb}^{-1}\) of proton–proton collision data recorded by the ATLAS experiment at \(\sqrt{s}=1...

A search for neutral heavy resonances is performed in the \(WW\rightarrow e\nu \mu \nu \) decay channel using pp collision data corresponding to an integrated luminosity of \(36.1\,\hbox {fb}^{-1}\), collected at a centre-of-mass energy of 13\(\,\text {TeV}\) by the ATLAS detector at the Large Hadron Collider. No evidence of such heavy resonances i...

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 36.1 fb−1 at a centre-of-mass energy of 13 TeV collected in 2015 and 2016 with the ATLAS detector at the Large Hadron Collider. Even...

The strong coupling constant αs(MZ) is determined using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Individual values of αs(MZ) are extracted from measurements of different experiments at several centre-of-mass energies, using QCD predictions complete in NNLO perturbation theory, suppleme...

Bose-Einstein correlations between identified charged pions are measured for p+Pb collisions at sNN=5.02TeV using data recorded by the ATLAS detector at the CERN Large Hadron Collider corresponding to a total integrated luminosity of 28nb−1. Pions are identified using ionization energy loss measured in the pixel detector. Two-particle correlation f...

The results of a search for squarks and gluinos in final states with an isolated electron or muon, multiple jets and large missing transverse momentum using proton-proton collision data at a center-of-mass energy of s=13 TeV are presented. The data set used was recorded during 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider and c...

Searches for new phenomena in high-mass diphoton final states with the ATLAS experiment at the LHC are presented. The analysis is based on pp collision data corresponding to an integrated luminosity of 36.7 fb⁻¹ at a centre-of-mass energy s=13 TeV recorded in 2015 and 2016. Searches are performed for resonances with spin 0, as predicted by theories...

Searches for new phenomena in high-mass diphoton final states with the ATLAS experiment at the LHC are presented. The analysis is based on pp collision data corresponding to an integrated luminosity of 36.7 fb−1 at a centre-of-mass energy s=13TeV recorded in 2015 and 2016. Searches are performed for resonances with spin 0, as predicted by theories...

The cross-section for the production of two jets in association with a leptonically decaying Z boson (Zjj ) is measured in proton–proton collisions at a centre-of-mass energy of 13 TeV, using data recorded with the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 3.2 fb−1. The electroweak Zjj cross-section i...

A search for dark matter in association with a Higgs boson decaying to two photons is presented. This study is based on data collected with the ATLAS detector, corresponding to an integrated luminosity of 36.1 fb−1 of proton-proton collisions at the LHC at a center-of-mass energy of 13 TeV in 2015 and 2016. No significant excess over the expected b...

As a part of the homage on Guido Altarelli, summarised in the book "From my vast repertoire - the legacy of Guido Altarelli" edited by S. Forte, A. Levy and G. Ridolfi, this contribution collects some of the technological and scientific highlights of precision physics at LEP, the Large Electron-Positron collider operated, from 1989 to 2000, at the...

The ATLAS inner detector comprises three different sub-detectors: the pixel detector, the silicon strip tracker, and the transition-radiation drift-tube tracker. The Insertable B-Layer, a new innermost pixel layer, was installed during the shutdown period in 2014, together with modifications to the layout of the cables and support structures of the...

The electroweak production and subsequent decay of single top quarks in the t-channel is determined by the properties of the Wtb vertex, which can be described by the complex parameters of an effective Lagrangian. An analysis of a triple-differential decay rate in t-channel production is used to simultaneously determine five generalised helicity fr...

This Letter presents the measurement of differential cross sections of isolated prompt photons produced in association with a b-jet or a c-jet. These final states provide sensitivity to the heavy-flavour content of the proton and aspects related to the modelling of heavy-flavour quarks in perturbative QCD. The measurement uses proton–proton collisi...

A search is presented for particles that decay producing a large jet multiplicity and invisible particles. The event selection applies a veto on the presence of isolated electrons or muons and additional requirements on the number of b-tagged jets and the scalar sum of masses of large-radius jets. Having explored the full ATLAS 2015-2016 dataset of...

Narrow resonances decaying into WW, WZ or ZZ boson pairs are searched for in 36.7 fb−1 of proton–proton collision data at a centre-of-mass energy of s=13 TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The diboson system is reconstructed using pairs of large-radius jets with high transverse momentum and tagged as...

A search for the decay of the Standard Model Higgs boson into a \( b\overline{b} \) pair when produced in association with a W or Z boson is performed with the ATLAS detector. The analysed data, corresponding to an integrated luminosity of 36.1 fb−1, were collected in proton-proton collisions in Run 2 of the Large Hadron Collider at a centre-of-mas...