Change search
Link to record
Permanent link

Direct link
Wallängen, VeronicaORCID iD iconorcid.org/0000-0003-1158-2686
Alternative names
Publications (10 of 522) Show all publications
Aad, G., Andrean, S. Y., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., . . . Zwalinski, L. (2024). Search for quantum black hole production in lepton+jet final states using proton-proton collisions at √s=13 TeV with the ATLAS detector. Physical Review D: covering particles, fields, gravitation, and cosmology, 109(3), Article ID 032010.
Open this publication in new window or tab >>Search for quantum black hole production in lepton+jet final states using proton-proton collisions at √s=13 TeV with the ATLAS detector
Show others...
2024 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 109, no 3, article id 032010Article in journal (Refereed) Published
Abstract [en]

A search for quantum black holes in electron+jet and muon+jet invariant mass spectra is performed with 140  fb−1 of data collected by the ATLAS detector in proton-proton collisions at √s=13  TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:su:diva-227769 (URN)10.1103/PhysRevD.109.032010 (DOI)001183228500014 ()2-s2.0-85187155078 (Scopus ID)
Available from: 2024-04-08 Created: 2024-04-08 Last updated: 2024-04-08Bibliographically approved
Aad, G., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., Hellman, S., . . . Zwalinski, L. (2023). Determination of the strong coupling constant from transverse energy-energy correlations in multijet events at √ s=13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP), 2023(7), Article ID 085.
Open this publication in new window or tab >>Determination of the strong coupling constant from transverse energy-energy correlations in multijet events at √ s=13 TeV with the ATLAS detector
Show others...
2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2023, no 7, article id 085Article in journal (Refereed) Published
Abstract [en]

Measurements of transverse energy-energy correlations and their associated azimuthal asymmetries in multijet events are presented. The analysis is performed using a data sample corresponding to 139 fb-1 of proton-proton collisions at a centre-of-mass energy of root s = 13TeV, collected with the ATLAS detector at the Large Hadron Collider. The measurements are presented in bins of the scalar sum of the transverse momenta of the two leading jets and unfolded to particle level. They are then compared to next-to-next-to-leading-order perturbative QCD calculations for the first time, which feature a significant reduction in the theoretical uncertainties estimated using variations of the renormalisation and factorisation scales. The agreement between data and theory is good, thus providing a precision test of QCD at large momentum transfers Q. The strong coupling constant alpha(s) is extracted as a function of Q, showing a good agreement with the renormalisation group equation and with previous analyses. A simultaneous fit to all transverse energy-energy correlation distributions across different kinematic regions yields a value of alpha(s)( mZ) = 0.1175 +/- 0.0006 (exp.)(+0.0034) (-0.0017) (theo.), while the global fit to the asymmetry distributions yields alpha(s)(m(Z)) = 0.1185 +/- 0.0009 (exp.)(+0.0025)(-0.0012)(theo.).

Keywords
Hadron-Hadron Scattering, Jet Physics, Jets
National Category
Subatomic Physics
Identifiers
urn:nbn:se:su:diva-223221 (URN)10.1007/JHEP07(2023)085 (DOI)001061751900001 ()2-s2.0-85165298184 (Scopus ID)
Available from: 2023-12-06 Created: 2023-12-06 Last updated: 2023-12-07Bibliographically approved
Aad, G., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., Hellman, S., . . . Zwalinski, L. (2023). Inclusive-photon production and its dependence on photon isolation in pp collisions at √s=13 TeV using 139 fb-1 of ATLAS data. Journal of High Energy Physics (JHEP), 2023(7), Article ID 086.
Open this publication in new window or tab >>Inclusive-photon production and its dependence on photon isolation in pp collisions at √s=13 TeV using 139 fb-1 of ATLAS data
Show others...
2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2023, no 7, article id 086Article in journal (Refereed) Published
Abstract [en]

Measurements of differential cross sections are presented for inclusive isolated photon production in pp collisions at a centre-of-mass energy of 13TeV provided by the LHC and using 139 fb-1 of data recorded by the ATLAS experiment. The cross sections are measured as functions of the photon transverse energy in different regions of photon pseudorapidity. The photons are required to be isolated by means of a fixed-cone method with two different cone radii. The dependence of the inclusive-photon production on the photon isolation is investigated by measuring the fiducial cross sections as functions of the isolation-cone radius and the ratios of the differential cross sections with different radii in different regions of photon pseudorapidity. The results presented in this paper constitute an improvement with respect to those published by ATLAS earlier: the measurements are provided for different isolation radii and with a more granular segmentation in photon pseudorapidity that can be exploited in improving the determination of the proton parton distribution functions. These improvements provide a more in-depth test of the theoretical predictions. Next-to-leading-order QCD predictions from JETPHOX and SHERPA and next-to-next-to-leading-order QCD predictions from NNLOJET are compared to the measurements, using several parameterisations of the proton parton distribution functions. The measured cross sections are well described by the fixed-order QCD predictions within the experimental and theoretical uncertainties in most of the investigated phase-space region.

Keywords
Hadron-Hadron Scattering
National Category
Subatomic Physics
Identifiers
urn:nbn:se:su:diva-223222 (URN)10.1007/JHEP07(2023)086 (DOI)001062449200001 ()2-s2.0-85165305389 (Scopus ID)
Available from: 2023-11-27 Created: 2023-11-27 Last updated: 2023-12-07Bibliographically approved
Aad, G., Andrean, S. Y., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., . . . Zwalinski, L. (2023). Measurement of cross sections for production of a Z boson in association with a flavor-inclusive or doubly b-tagged large-radius jet in proton-proton collisions at √s=13 TeV with the ATLAS experiment. Physical Review D: covering particles, fields, gravitation, and cosmology, 108(1), Article ID 012022.
Open this publication in new window or tab >>Measurement of cross sections for production of a Z boson in association with a flavor-inclusive or doubly b-tagged large-radius jet in proton-proton collisions at √s=13 TeV with the ATLAS experiment
Show others...
2023 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, no 1, article id 012022Article in journal (Refereed) Published
Abstract [en]

We present measurements of cross sections for production of a leptonically decaying Z boson in association with a large-radius jet in 13 TeV proton-proton collisions at the LHC, using 36  fb−1 of data from the ATLAS detector. Integrated and differential cross sections are measured at particle level in both a flavor inclusive and a doubly b-tagged fiducial phase space. The large-radius jet mass and transverse momentum, its kinematic relationship to the Z boson, and the angular separation of b-tagged small-radius track jets within the large-radius jet are measured. This measurement constitutes an important test of perturbative quantum chromodynamics in kinematic and flavor configurations relevant to several Higgs boson and beyond-Standard-Model physics analyses. The results highlight issues with modeling of additional hadronic activity in the flavor-inclusive selection, and a distinction between flavor-number schemes in the b-tagged phase space.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:su:diva-223715 (URN)10.1103/PhysRevD.108.012022 (DOI)001055270000001 ()2-s2.0-85173651854 (Scopus ID)
Available from: 2023-11-16 Created: 2023-11-16 Last updated: 2023-11-16Bibliographically approved
Backman, F., Bertoli, G., Bohm, C., Carney, R. M. D., Clément, C., Hellman, S., . . . Wallängen, V. (2023). Measurement of the inclusive t¯t production cross section in the lepton+jets channel in pp collisions at √s=7  TeV with the ATLAS detector using support vector machines. Physical Review D: covering particles, fields, gravitation, and cosmology, 108(3), Article ID 032014.
Open this publication in new window or tab >>Measurement of the inclusive t¯t production cross section in the lepton+jets channel in pp collisions at √s=7  TeV with the ATLAS detector using support vector machines
Show others...
2023 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, no 3, article id 032014Article in journal (Refereed) Published
Abstract [en]

A measurement of the top quark pair-production cross section in the lepton+jets decay channel is presented. It is based on 4.6  fb−1 of √s=7  TeV pp collision data collected during 2011 by the ATLAS experiment at the CERN Large Hadron Collider. A three-class, multidimensional event classifier based on support vector machines is used to differentiate t¯t events from backgrounds. The t¯t production cross section is found to be σt¯t=168.5±0.7(stat) +6.2−5.9(syst) +3.4−3.2(lumi)  pb. The result is consistent with the Standard Model prediction based on QCD calculations at next-to-next-to-leading order.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:su:diva-223860 (URN)10.1103/PhysRevD.108.032014 (DOI)001063420300001 ()2-s2.0-85173785320 (Scopus ID)
Available from: 2023-11-22 Created: 2023-11-22 Last updated: 2023-11-22Bibliographically approved
Aad, G., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., Hellman, S., . . . Zwalinski, L. (2023). Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP), 2023(6), Article ID 19.
Open this publication in new window or tab >>Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at √s = 13 TeV with the ATLAS detector
Show others...
2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2023, no 6, article id 19Article in journal (Refereed) Published
Abstract [en]

A measurement of the top-quark mass (mt) in the → lepton + jets channel is presented, with an experimental technique which exploits semileptonic decays of b-hadrons produced in the top-quark decay chain. The distribution of the invariant mass mℓμ of the lepton, ℓ (with ℓ = e, μ), from the W-boson decay and the muon, μ, originating from the b-hadron decay is reconstructed, and a binned-template profile likelihood fit is performed to extract mt. The measurement is based on data corresponding to an integrated luminosity of 36.1 fb−1 of √s = 13 TeV pp collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. The measured value of the top-quark mass is mt = 174.41 ± 0.39 (stat.) ± 0.66 (syst.) ± 0.25 (recoil) GeV, where the third uncertainty arises from changing the PYTHIA8 parton shower gluon-recoil scheme, used in top-quark decays, to a recently developed setup.

Keywords
Hadron-Hadron Scattering, Top Physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:su:diva-221776 (URN)10.1007/JHEP06(2023)019 (DOI)001035480600001 ()2-s2.0-85161860997 (Scopus ID)
Available from: 2023-10-03 Created: 2023-10-03 Last updated: 2023-10-03Bibliographically approved
Aad, G., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., Hellman, S., . . . Zwalinski, L. (2023). Model-independent search for the presence of new physics in events including H → γγ with √s=13 TeV pp data recorded by the ATLAS detector at the LHC. Journal of High Energy Physics (JHEP), 2023(7), Article ID 176.
Open this publication in new window or tab >>Model-independent search for the presence of new physics in events including Hγγ with √s=13 TeV pp data recorded by the ATLAS detector at the LHC
Show others...
2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2023, no 7, article id 176Article in journal (Refereed) Published
Abstract [en]

A model-independent search for new physics leading to final states containing a Higgs boson, with a mass of 125.09 GeV, decaying to a pair of photons is performed with 139 fb-1 of p root s = 13TeV pp collision data recorded by the ATLAS detector at the Large Hadron Collider at CERN. This search examines 22 final states categorized by the objects that are produced in association with the Higgs boson. These objects include isolated electrons or muons, hadronically decaying iota -leptons, additional photons, missing transverse momentum, and hadronic jets, as well as jets that are tagged as containing a b-hadron. No significant excesses above Standard Model expectations are observed and limits on the production cross section at 95% confidence level are set. Detector efficiencies are reported for all 22 signal regions, which can be used to convert detector-level cross-section limits reported in this paper to particle-level cross-section constraints.

Keywords
Hadron-Hadron Scattering, Higgs Physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:su:diva-223223 (URN)10.1007/JHEP07(2023)176 (DOI)001062072300001 ()2-s2.0-85172300035 (Scopus ID)
Available from: 2023-12-01 Created: 2023-12-01 Last updated: 2024-04-24Bibliographically approved
Aad, G., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., Hellman, S., . . . Zwalinski, L. (2023). Observation of electroweak production of two jets and a Z-boson pair. Nature Physics, 19(2), 237-253
Open this publication in new window or tab >>Observation of electroweak production of two jets and a Z-boson pair
Show others...
2023 (English)In: Nature Physics, ISSN 1745-2473, E-ISSN 1745-2481, Vol. 19, no 2, p. 237-253Article in journal (Refereed) Published
Abstract [en]

Electroweak symmetry breaking explains the origin of the masses of elementary particles through their interactions with the Higgs field. Besides the measurements of the Higgs boson properties, the study of the scattering of massive vector bosons with spin 1 allows the nature of electroweak symmetry breaking to be probed. Among all processes related to vector-boson scattering, the electroweak production of two jets and a Z-boson pair is a rare and important one. Here we report the observation of this process from proton–proton collision data corresponding to an integrated luminosity of 139 fb−1 recorded at a centre-of-mass energy of 13 TeV with the ATLAS detector at the Large Hadron Collider. We consider two different final states originating from the decays of the Z-boson pair: one containing four charged leptons and another containing two charged leptons and two neutrinos. The hypothesis of no electroweak production is rejected with a statistical significance of 5.7σ, and the measured cross-section for electroweak production is consistent with the Standard Model prediction. In addition, we report cross-sections for inclusive production of a Z-boson pair and two jets for the two final states.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:su:diva-224598 (URN)10.1038/s41567-022-01757-y (DOI)001005403200001 ()2-s2.0-85158900669 (Scopus ID)
Available from: 2023-12-22 Created: 2023-12-22 Last updated: 2024-03-08Bibliographically approved
Aad, G., Andrean, S. Y., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., . . . Zwalinski, L. (2022). Constraints on Higgs boson properties using W W∗(→ eνμν) j j production in 36.1 fb−1 of √s = 13 TeV pp collisions with the ATLAS detector. European Physical Journal C, 82(7), Article ID 622.
Open this publication in new window or tab >>Constraints on Higgs boson properties using W W∗(→ eνμν) j j production in 36.1 fb−1 of √s = 13 TeV pp collisions with the ATLAS detector
Show others...
2022 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 82, no 7, article id 622Article in journal (Refereed) Published
Abstract [en]

This article presents the results of two studies of Higgs boson properties using the W W∗(→ eνμν)j j final state, based on a dataset corresponding to 36.1fb−1of √s = 13 TeV proton–proton collisions recorded by the ATLAS experiment at the Large Hadron Collider. The first study targets Higgs boson production via gluon–gluon fusion and constrains the CP properties of the effective Higgs–gluon interaction. Using angular distributions and the overall rate, a value of tan(α) = 0.0 ± 0.4(stat.) ± 0.3(syst.) is obtained for the tangent of the mixing angle for CP-even and CP-odd contributions. The second study exploits the vector-boson fusion production mechanism to probe the Higgs boson couplings to longitudinally and transversely polarised Wand Z bosons in both the production and the decay of the Higgs boson; these couplings have not been directly constrained previously. The polarisation-dependent coupling strength scale factors are defined as the ratios of the  measured polarisation-dependent coupling strengths to those predictedby the Standard Model, and are determined using rate and kinematic information to be aL = 0.91+0.10 −0.18(stat.)+0.09 −0.17(syst.)and aT = 1.2 ± 0.4(stat.)+0.2 −0.3(syst.). These coupling strengths are translated into pseudo-observables, resulting in κV V = 0.91+0.10 −0.18(stat.)+0.09 −0.17(syst.) and ϵV V = 0.13+0.28 −0.20(stat.)+0.08 −0.10(syst.). All results are consistent with the Standard Model predictions.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-208224 (URN)10.1140/epjc/s10052-022-10366-1 (DOI)000826946000001 ()2-s2.0-85134522243 (Scopus ID)
Available from: 2022-09-02 Created: 2022-09-02 Last updated: 2022-09-02Bibliographically approved
Aad, G., Andrean, S. Y., Backman, F., Barranco Navarro, L., Bohm, C., Clément, C., . . . Zwalinski, L. (2022). Emulating the impact of additional proton–proton interactions in the ATLAS simulation by presampling sets of inelastic Monte Carlo events. Computing and Software for Big Science, 6(1), Article ID 3.
Open this publication in new window or tab >>Emulating the impact of additional proton–proton interactions in the ATLAS simulation by presampling sets of inelastic Monte Carlo events
Show others...
2022 (English)In: Computing and Software for Big Science, E-ISSN 2510-2044, Vol. 6, no 1, article id 3Article in journal (Refereed) Published
Abstract [en]

The accurate simulation of additional interactions at the ATLAS experiment for the analysis of proton–proton collisions delivered by the Large Hadron Collider presents a significant challenge to the computing resources. During the LHC Run 2 (2015–2018), there were up to 70 inelastic interactions per bunch crossing, which need to be accounted for in Monte Carlo (MC) production. In this document, a new method to account for these additional interactions in the simulation chain is described. Instead of sampling the inelastic interactions and adding their energy deposits to a hard-scatter interaction one-by-one, the inelastic interactions are presampled, independent of the hard scatter, and stored as combined events. Consequently, for each hard-scatter interaction, only one such presampled event needs to be added as part of the simulation chain. For the Run 2 simulation chain, with an average of 35 interactions per bunch crossing, this new method provides a substantial reduction in MC production CPU needs of around 20%, while reproducing the properties of the reconstructed quantities relevant for physics analyses with good accuracy. 

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:su:diva-206752 (URN)10.1007/s41781-021-00062-2 (DOI)2-s2.0-85124276335 (Scopus ID)
Available from: 2022-06-23 Created: 2022-06-23 Last updated: 2022-06-23Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1158-2686

Search in DiVA

Show all publications