| 1. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of differential cross sections and W+/W- cross-section ratios for W boson production in association with jets at root s=8 TeV with the ATLAS detector
- 2018
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer-Verlag New York. - 1126-6708 .- 1029-8479. ; :5
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Tidskriftsartikel (refereegranskat)abstract
- 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 root 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 using data corresponding to an integrated luminosity of 20.2 fb(-1). Differential cross sections for events with at least one or two jets are presented for a range of observables, including jet transverse momenta and rapidities, the scalar sum of transverse momenta of the visible particles and the missing transverse momentum in the event, and the transverse momentum of the W boson. For a subset of the observables, the differential cross sections of positively and negatively charged W bosons are measured separately. In the cross-section ratio of W+/W- the dominant systematic uncertainties cancel out, improving the measurement precision by up to a factor of nine. The observables and ratios selected for this paper provide valuable input for the up quark, down quark, and gluon parton distribution functions of the proton.
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| 2. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of inclusive jet and dijet cross-sections in proton-proton collisions at root s=13 TeV with the ATLAS detector
- 2018
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Ingår i: Journal of High Energy Physics (JHEP). - : SPRINGER. - 1126-6708 .- 1029-8479. ; :5
-
Tidskriftsartikel (refereegranskat)abstract
- Inclusive jet and dijet cross-sections are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The measurement uses a dataset with an integrated luminosity of 3.2 fb(-1) recorded in 2015 with the ATLAS detector at the Large Hadron Collider. Jets are identified using the anti-lit algorithm with a radius parameter value of R = 0.4. The inclusive jet cross-sections are measured double-differentially as a function of the jet transverse momentum, covering the range from 100 GeV to 3.5 TeV, and the absolute jet rapidity up to vertical bar y vertical bar = 3. The double-differential dijet production cross-sections are presented as a function of the dijet mass, covering the range from 300 GeV to 9 TeV, and the half absolute rapidity separation between the two leading jets within vertical bar y vertical bar < 3, y*, up to y* = 3. Next-to-leading-order, and next-to-next-to-leading-order for the inclusive jet measurement, perturbative QCD calculations corrected for non-perturbative and electroweak effects are compared to the measured cross-sections.
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| 3. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of long-range multiparticle azimuthal correlations with the subevent cumulant method in pp and p plus Pb collisions with the ATLAS detector at the CERN Large Hadron Collider
- 2018
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 97:2
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Tidskriftsartikel (refereegranskat)abstract
- A detailed study of multiparticle azimuthal correlations is presented using pp data at root s = 5.02 and 13 TeV, and p+Pb data at root s(NN) = 5.02 TeV, recorded with the ATLAS detector at the CERN Large Hadron Collider. The azimuthal correlations are probed using four-particle cumulants c(n){4} and flow coefficients v(n){4} = (-c(n){4})(1/4) for n = 2 and 3, with the goal of extracting long-range multiparticle azimuthal correlation signals and suppressing the short-range correlations. The values of c(n){4} are obtained as a function of the average number of charged particles per event, < N-ch >, using the recently proposed two-subevent and three-subevent cumulant methods, and compared with results obtained with the standard cumulant method. The standard method is found to be strongly biased by short-range correlations, which originate mostly from jetswith a positive contribution to c(n){4}. The threesubevent method, on the other hand, is found to be least sensitive to short-range correlations. The three-subevent method gives a negative c(2){4}, and therefore a well-defined v(2){4}, nearly independent of < N-ch >, which implies that the long-range multiparticle azimuthal correlations persist to events with low multiplicity. Furthermore, v(2){4} is found to be smaller than the v(2){2} measured using the two-particle correlation method, as expected for long-range collective behavior. Finally, the measured values of v(2){4} and v(2){2} are used to estimate the number of sources relevant for the initial eccentricity in the collision geometry. The results based on the subevent cumulant technique provide direct evidence, in small collision systems, for a long-range collectivity involving many particles distributed across a broad rapidity interval.
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| 4. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of the Higgs boson coupling properties in the H -> ZZ* -> 4l decay channel at root s=13 TeV with the ATLAS detector
- 2018
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :3
-
Tidskriftsartikel (refereegranskat)abstract
- The coupling properties of the Higgs boson are studied in the four-lepton (e, mu) 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 are interpreted in terms of coupling modifiers. The inclusive cross section times branching ratio for H -> ZZ* decay and for a Higgs boson absolute rapidity below 2.5 is measured to be 1.73(-0.23)(+0.24)(stat.)(-0.08)(+0.10)(exp.)+/- 0.04(th.) pb compared to the Standard Model prediction of 1.34 +/- 0.09 pb. In addition, the tensor structure. of the Higgs boson couplings is studied using an effective Lagrangian approach for the description of interactions beyond the Standard Model. Constraints are placed on the non-Standard-Model CP-even and CP-odd couplings to Z bosons and on the CP-odd coupling to gluons.
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| 5. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of the production cross-section of a single top quark in association with a Z boson in proton-proton collisions at 13 TeV with the ATLAS detector
- 2018
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 780, s. 557-577
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Tidskriftsartikel (refereegranskat)abstract
- 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 root s = 13 TeV are used, corresponding to an integrated luminosity of 36.1 fb(-1). Events containing three identified leptons (electrons and/or muons) and two jets, one of which is identified as a b-quark jet are selected. The major backgrounds are diboson, tt($)over-bar and Z + jets production. A neural network is used to improve the background rejection and extract the signal. The resulting significance is 4.2 sigma in the data and the expected significance is 5.4 sigma. The measured cross-section for tZq production is 600 +/- 170(stat.)+/- 140(syst.)fb.
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| 6. |
- Abulaiti, Yiming, et al.
(författare)
-
Search for additional heavy neutral Higgs and gauge bosons in the ditau final state produced in 36 fb(-1) of pp collisions at root s=13 TeV with the ATLAS detector
- 2018
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :1
-
Tidskriftsartikel (refereegranskat)abstract
- 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 root s = 13 TeV recorded by the ATLAS detector at the LHC during 2015 and 2016. The heavy resonance is assumed to decay to tau(+)tau(-) with at least one tau lepton decaying to final states with hadrons and a neutrino. The search is performed in the mass range of 0.2-2.25 TeV for Higgs bosons and 0.2-4.0 TeV for Z' bosons. The data are in good agreement with the background predicted by the Standard Model. The results are interpreted in benchmark scenarios. In the context of the hMSSM scenario, the data exclude tan beta > 1.0 for m(A) = 0.25 TeV and tan beta > 42 for m(A) = 1.5 TeV at the 95% confidence level. For the Sequential Standard Model, Z'(SSM) with m(Z') < 2.42 TeV is excluded at 95% confidence level, while Z'(NU) with m(Z') < 2.25 TeV is excluded for the non-universal G(221) model that exhibits enhanced couplings to third-generation fermions.
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| 7. |
- Abulaiti, Yiming, et al.
(författare)
-
Search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a Z boson in pp collisions at root s=13 TeV with the ATLAS detector
- 2018
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445 .- 0009-2614 .- 1873-4448. ; 776, s. 318-337
-
Tidskriftsartikel (refereegranskat)abstract
- 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 root 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 Model backgrounds is observed. Assuming the Standard Model ZH production cross-section, an observed (expected) upper limit of 67% (39%) at the 95% confidence level is set on the branching ratio of invisible decays of the Higgs boson with mass m(H) = 125 GeV. The corresponding limits on the production cross-section of the ZH process with the invisible Higgs boson decays are also presented. Furthermore, exclusion limits on the dark matter candidate and mediator masses are reported in the framework of simplified dark matter models.
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| 8. |
- Abulaiti, Yiming, et al.
(författare)
-
Search for dark matter and other new phenomena in events with an energetic jet and large missing transverse momentum using the ATLAS detector
- 2018
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :1
-
Tidskriftsartikel (refereegranskat)abstract
- 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. Events are required to have at least one jet with a transverse momentum above 250 GeV and no leptons (e or mu). Several signal regions are considered with increasing requirements on the missing transverse momentum above 250 GeV. Good agreement is observed between the number of events in data and Standard Model predictions. The results are translated into exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, and supersymmetric particles in several compressed scenarios.
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| 9. |
- Abulaiti, Yiming, et al.
(författare)
-
Search for dark matter produced in association with bottom or top quarks in root s=13 TeV pp collisions with the ATLAS detector
- 2018
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 78:1
-
Tidskriftsartikel (refereegranskat)abstract
- 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 fb(-1) of proton proton collision data recorded by the ATLAS experiment at root s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are interpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour-neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross-section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour-charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements.
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| 10. |
- Abulaiti, Yiming, et al.
(författare)
-
Search for doubly charged Higgs boson production in multi-lepton final states with the ATLAS detector using proton-proton collisions at root s=13TeV
- 2018
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 78:3
-
Tidskriftsartikel (refereegranskat)abstract
- 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 analysis focuses on the decays H-+/-+/- -> e(+/-)e(+/-), H-+/-+/- -> e(+/-)mu(+/-) and H-+/-+/- -> mu(+/-)mu(+/-), fitting the dilepton mass spectra in several exclusive signal regions. No significant evidence of a signal is observed and corresponding limits on the production cross-section and consequently a lower limit on m(H-+/-+/-) are derived at 95% confidence level. With l(+/-)l(+/-) = e(+/-)e(+/-)/mu(+/-)mu(+/-)/e(+/-)mu(+/-), the observed lower limit on the mass of a doubly charged Higgs boson only coupling to left-handed leptons varies from 770 to 870GeV (850GeV expected) for B(H-+/-+/- -> l(+/-)l(+/-)) = 100% and both the expected and observed mass limits are above 450GeV for B(H-+/-+/- -> l(+/-)l(+/-)) = 10% and any combination of partial branching ratios.
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| 11. |
- Abulaiti, Yiming, et al.
(författare)
-
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 root s=13 TeV pp collisions with the ATLAS detector
- 2018
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :3
-
Tidskriftsartikel (refereegranskat)abstract
- A search is conducted for new resonances decaying into a W or Z boson and a 125 GeV Higgs boson in the nu(nu) over barb (b) over bar, l(+/-)nu b (b) over bar, and l(+)l(-)b (b) over bar final states, where l(+/-) = e(+/-) or mu(+/-), in pp collisions at root s = 13 TeV. The data used correspond to a total integrated luminosity of 36.1 fb(-1) collected with the ATLAS detector at the Large Hadron Collider during the 2015 and 2016 data-taking periods. The search is conducted by examining the reconstructed invariant or transverse mass distributions of Wh and Zh candidates for evidence of a localised excess in the mass range of 220 GeV up to 5 TeV. No significant excess is observed and the results are interpreted in terms of constraints on the production cross-section times branching fraction of heavy W' and Z' resonances in heavy-vector-triplet models and the CP-odd scalar boson A in two-Higgs-doublet models. Upper limits are placed at the 95% confidence level and range between 9.0 x 10(-4) pb and 7.3 x 10(-1) pb depending on the model and mass of the resonance.
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| 12. |
- Abulaiti, Yiming, et al.
(författare)
-
Search for heavy ZZ resonances in the l(+) l(-) l(+) l(-) and l(+) l(-) nu(nu)over-bar final states using proton-proton collisions at root s=13 TeV with the ATLAS detector
- 2018
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 78:4
-
Tidskriftsartikel (refereegranskat)abstract
- A search for heavy resonances decaying into a pair of Z bosons leading to l(+) l(-) l(+) l(-) and l(+) l(-) nu(nu) over bar final states, where l 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 TeV corresponding to an integrated luminosity of 36.1 fb(-1) collected with the ATLAS detector during 2015 and 2016 at the Large Hadron Collider. Different mass ranges for the hypothetical resonances are considered, depending on the final state and model. The different ranges span between 200 and 2000 GeV. The results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, while those for the spin-2 resonance are used to constrain the Randall-Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.
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| 13. |
- Abulaiti, Yiming, et al.
(författare)
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Search for WW/WZ resonance production in lvqq final states in pp collisions at root s=13 TeV with the ATLAS detector
- 2018
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :3
-
Tidskriftsartikel (refereegranskat)abstract
- A search is conducted for new resonances decaying into a WW or WZ 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 root s = 13 TeV in 2015 and 2016. The search is sensitive to diboson resonance production via vector-boson fusion as well as quark-antiquark annihilation and gluon-gluon fusion mechanisms. No significant excess of events is observed with respect to the Standard Model backgrounds. Several benchmark models are used to interpret the results. Limits on the production cross section are set for a new narrow scalar resonance, a new heavy vector-boson and a spin-2 Kaluza-Klein graviton.
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| 14. |
- Milstead, David A., et al.
(författare)
-
Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector
- 2018
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 97:7
-
Tidskriftsartikel (refereegranskat)abstract
- A search for the associated production of the Higgs boson with a top quark pair (ttH) 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 Collider. Higgs boson decays to WW∗, ττ, and ZZ∗ are targeted. Seven final states, categorized by the number and flavor of charged-lepton candidates, are examined for the presence of the Standard Model Higgs boson with a mass of 125 GeV and a pair of top quarks. An excess of events over the expected background from Standard Model processes is found with an observed significance of 4.1 standard deviations, compared to an expectation of 2.8 standard deviations. The best fit for the ttH production cross section is σ(ttH)=790-210+230 fb, in agreement with the Standard Model prediction of 507-50+35 fb. The combination of this result with other ttH searches from the ATLAS experiment using the Higgs boson decay modes to bb, γγ and ZZ∗→4, has an observed significance of 4.2 standard deviations, compared to an expectation of 3.8 standard deviations. This provides evidence for the ttH production mode. © 2018 CERN, for the ATLAS Collaboration. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.
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| 15. |
- Milstead, David A., et al.
(författare)
-
Measurement of differential cross-sections of a single top quark produced in association with a W boson at √s=13TeV with ATLAS
- 2018
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 78:3
-
Tidskriftsartikel (refereegranskat)abstract
- 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 36.1fb-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 space defined by the presence of two charged leptons and exactly one jet matched to a b-hadron, and are normalised with the fiducial cross-section. Results are found to be in good agreement with predictions from several Monte Carlo event generators. © 2018, CERN for the benefit of the ATLAS collaboration.
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| 16. |
- Milstead, David A., et al.
(författare)
-
Measurement of differential cross sections of isolated-photon plus heavy-flavour jet production in pp collisions at s=8 TeV using the ATLAS detector
- 2018
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 0009-2614 .- 1873-4448 .- 1873-2445. ; 776, s. 295-317
-
Tidskriftsartikel (refereegranskat)abstract
- 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 collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of up to 20.2 fb−1. The differential cross sections are measured for each jet flavour with respect to the transverse energy of the leading photon in two photon pseudorapidity regions: |ηγ|<1.37 and 1.56<|ηγ|<2.37. The measurement covers photon transverse energies 25
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| 17. |
- Milstead, David A., et al.
(författare)
-
Measurement of the production cross section of three isolated photons in pp collisions at s=8 TeV using the ATLAS detector
- 2018
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 781, s. 55-76
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Tidskriftsartikel (refereegranskat)abstract
- 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 difference in azimuthal angle and in pseudorapidity between pairs of photons, the invariant mass of pairs of photons, and the invariant mass of the triphoton system. A measurement of the inclusive fiducial cross section is also reported. Next-to-leading-order perturbative QCD predictions are compared to the cross-section measurements. The predictions underestimate the measurement of the inclusive fiducial cross section and the differential measurements at low photon transverse energies and invariant masses. They provide adequate descriptions of the measurements at high values of the photon transverse energies, invariant mass of pairs of photons, and invariant mass of the triphoton system. © 2018 The Author
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| 18. |
- Milstead, David A., et al.
(författare)
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Search for electroweak production of supersymmetric states in scenarios with compressed mass spectra at s =13 TeV with the ATLAS detector
- 2018
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 97
-
Tidskriftsartikel (refereegranskat)abstract
- 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 integrated luminosity at s=13 TeV. Events with same-flavor pairs of electrons or muons with opposite electric charge are selected. The data are found to be consistent with the Standard Model prediction. Results are interpreted using simplified models of R-parity-conserving supersymmetry in which there is a small mass difference between the masses of the produced supersymmetric particles and the lightest neutralino. Exclusion limits at 95% confidence level are set on next-to-lightest neutralino masses of up to 145 GeV for Higgsino production and 175 GeV for wino production, and slepton masses of up to 190 GeV for pair production of sleptons. In the compressed mass regime, the exclusion limits extend down to mass splittings of 2.5 GeV for Higgsino production, 2 GeV for wino production, and 1 GeV for slepton production. The results are also interpreted in the context of a radiatively-driven natural supersymmetry model with nonuniversal Higgs boson masses. © 2018 CERN. © 2018 CERN, for the ATLAS Collaboration. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.
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| 19. |
- Milstead, David A., et al.
(författare)
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Search for heavy resonances decaying into WW in the e final state in pp collisions at √s=13TeV with the ATLAS detector
- 2018
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 78:1
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Tidskriftsartikel (refereegranskat)abstract
- A search for neutral heavy resonances is performed in the WW→ e decay channel using pp collision data corresponding to an integrated luminosity of 36.1fb-1, collected at a centre-of-mass energy of 13TeV by the ATLAS detector at the Large Hadron Collider. No evidence of such heavy resonances is found. In the search for production via the quark–antiquark annihilation or gluon–gluon fusion process, upper limits on σX× B(X→ WW) as a function of the resonance mass are obtained in the mass range between 200GeV and up to 5TeV for various benchmark models: a Higgs-like scalar in different width scenarios, a two-Higgs-doublet model, a heavy vector triplet model, and a warped extra dimensions model. In the vector-boson fusion process, constraints are also obtained on these resonances, as well as on a Higgs boson in the Georgi–Machacek model and a heavy tensor particle coupling only to gauge bosons. © 2018, CERN for the benefit of the ATLAS collaboration.
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| 20. |
- Milstead, David A., et al.
(författare)
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Search for High-Mass Resonances Decaying to τν in pp Collisions at s =13 TeV with the ATLAS Detector
- 2018
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 1079-7114 .- 0031-9007. ; 120:16
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Tidskriftsartikel (refereegranskat)abstract
- 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 excess above the standard model expectation is observed; model-independent upper limits are set on the visible τν production cross section. Heavy W′ bosons with masses less than 3.7 TeV in the sequential standard model and masses less than 2.2-3.8 TeV depending on the coupling in the nonuniversal G(221) model are excluded at the 95% credibility level. © 2018 CERN. © 2018 CERN, for the ATLAS Collaboration. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.
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| 21. |
- Milstead, David A., et al.
(författare)
-
Search for the Decay of the Higgs Boson to Charm Quarks with the ATLAS Experiment
- 2018
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 1079-7114 .- 0031-9007. ; 120:21
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Tidskriftsartikel (refereegranskat)abstract
- 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→ + -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 identified using charm-tagging algorithms. The observed (expected) upper limit on σ(pp→ZH)×B(H→cc) is 2.7 (3.9-1.1+2.1) pb at the 95% confidence level for a Higgs boson mass of 125 GeV, while the standard model value is 26 fb. © 2018 CERN.
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| 22. |
- Milstead, David A., et al.
(författare)
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Search for the standard model Higgs boson produced in association with top quarks and decaying into a b b pair in pp collisions at s =13 TeV with the ATLAS detector
- 2018
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 97:7
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Tidskriftsartikel (refereegranskat)abstract
- A search for the standard model Higgs boson produced in association with a top-quark pair, ttH, 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 or muons from the top-quark decays, and are then categorized according to the number of jets and how likely these are to contain b-hadrons. Multivariate techniques are used to discriminate between signal and background events, the latter being dominated by tt+jets production. For a Higgs boson mass of 125 GeV, the ratio of the measured ttH signal cross-section to the standard model expectation is found to be μ=0.84-0.61+0.64. A value of μ greater than 2.0 is excluded at 95% confidence level (C.L.) while the expected upper limit is μ
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| 23. |
- Milstead, David A., et al.
(författare)
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Search for W′ → tb decays in the hadronic final state using pp collisions at s=13TeV with the ATLAS detector
- 2018
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 781, s. 327-348
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Tidskriftsartikel (refereegranskat)abstract
- 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. Identification of the hadronically decaying top quark is performed using jet substructure tagging techniques based on a shower deconstruction algorithm. No significant deviation from the Standard Model prediction is observed and the results are expressed as upper limits on the W′→tb¯ production cross-section times branching ratio as a function of the W′-boson mass. These limits exclude W′ bosons with right-handed couplings with masses below 3.0 TeV and W′ bosons with left-handed couplings with masses below 2.9 TeV, at the 95% confidence level. © 2018 The Author
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| 24. |
- Mullier, G.A., et al.
(författare)
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Measurement of the energy response of the ATLAS calorimeter to charged pions from W±→ τ±(→ π±ντ) ντ events in Run 2 data
- 2022
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 82:3
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Tidskriftsartikel (refereegranskat)abstract
- The energy response of the ATLAS calorimeter is measured for single charged pions with transverse momentum in the range 10 < pT< 300 GeV. The measurement is performed using 139 fb - 1 of LHC proton–proton collision data at s=13 TeV taken in Run 2 by the ATLAS detector. Charged pions originating from τ-lepton decays are used to provide a sample of high-pT isolated particles, where the composition is known, to test an energy regime that has not previously been probed by in situ single-particle measurements. The calorimeter response to single-pions is observed to be overestimated by ∼ 2 % across a large part of the pT spectrum in the central region and underestimated by ∼ 4 % in the endcaps in the ATLAS simulation. The uncertainties in the measurements are ≲ 1 % for 15 < pT< 185 GeV in the central region. To investigate the source of the discrepancies, the width of the distribution of the ratio of calorimeter energy to track momentum, the energies per layer and response in the hadronic calorimeter are also compared between data and simulation. © 2022, The Author(s).
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| 25. |
- Aaboud, M, et al.
(författare)
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Combination of inclusive and differential (Formula Presented) charge asymmetry measurements using ATLAS and CMS data at (Formula Presented)= 7 and 8 TeV
- 2018
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2018:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents combinations of inclusive and differential measurements of the charge asymmetry (AC) in top quark pair (tt) events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centreof- mass energies of 7 and 8TeV. The data correspond to integrated luminosities of about 5 and 20 fb–1for each experiment, respectively. The resulting combined LHC measurements of the inclusive charge asymmetry are AC LHC7= 0:005±0:007 (stat) ±0:006 (syst) at 7TeV and AC LHC7= 0:0055 ± 0:0023 (stat) ± 0:0025 (syst) at 8TeV. These values, as well as the combination of AC measurements as a function of the invariant mass of the [formula presented] system at 8TeV, are consistent with the respective standard model predictions. © CERN, for the benefit of the ATLAS-CMS Collaboration.
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