Logo: to the web site of Uppsala University

uu.sePublications from Uppsala University
Change search
Link to record
Permanent link

Direct link
Alternative names
Publications (10 of 1,224) Show all publications
Aad, G., Bergeås Kuutmann, E., Brenner, R., Dimitriadi, C., Ekelöf, T., Ellajosyula, V., . . . Zwalinski, L. (2024). Measurement of the tt- section and its ratio to the Z production cross √section using pp collisions at √ˆšs=13.6 TeV with the ATLAS detector. Physics Letters B, 848, Article ID 138376.
Open this publication in new window or tab >>Measurement of the tt- section and its ratio to the Z production cross √section using pp collisions at √ˆšs=13.6 TeV with the ATLAS detector
Show others...
2024 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 848, article id 138376Article in journal (Refereed) Published
Abstract [en]

The inclusive top-quark-pair production cross section rrtt and its ratio to the Z-boson production cross section have been measured in proton-proton collisions at root s = 13.6 TeV, using 29 fb-1 of data collected in 2022 with the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge electron-muon pair and b-tagged jets, and assuming Standard Model decays, the top-quark-pair production cross section is measured to be rrtt = 850 +/- 3(stat.) +/- 18(syst.) +/- 20(lumi.) pb. The ratio of the ttand the Z-boson production cross sections is also measured, where the Z-boson contribution is determined for inclusive e+e- and mu+mu- events in a fiducial phase space. The relative uncertainty on the ratio is reduced compared to the ttcross section, thanks to the cancellation of several systematic uncertainties. The result for the ratio, Rtt/Z = 1.145 +/- 0.003(stat.) +/- 0.021(syst.) +/- 0.002(lumi.) is consistent with the Standard Model prediction using the PDF4LHC21 PDF set.

Place, publisher, year, edition, pages
Elsevier, 2024
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-522334 (URN)10.1016/j.physletb.2023.138376 (DOI)001136441300001 ()
Note

For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2023.138376

Available from: 2024-02-05 Created: 2024-02-05 Last updated: 2024-02-05Bibliographically approved
Aad, G., Bergeås Kuutmann, E., Brenner, R., Dimitriadi, C., Ekelöf, T., Ellajosyula, V., . . . Zwalinski, L. (2024). Search for non-resonant production of semi-visible jets using Run 2 data in ATLAS. Physics Letters B, 848, Article ID 138324.
Open this publication in new window or tab >>Search for non-resonant production of semi-visible jets using Run 2 data in ATLAS
Show others...
2024 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 848, article id 138324Article in journal (Refereed) Published
Abstract [en]

Semi-visible jets, with a significant contribution to the event's missing transverse momentum, can arise in strongly interacting dark sectors. This results in an event topology where one of the jets can be aligned with the direction of the missing transverse momentum. The first search for semi-visible jets produced via a t-channel mediator exchange is presented. The analysis uses proton-proton collisions with an integrated luminosity of 139 fb-1 and a centre-of-mass energy of 13 TeV, collected with the ATLAS detector during the Run 2 of the LHC. No excess over Standard Model predictions is observed. Assuming a coupling strength of unity between the mediator, a Standard Model quark and a dark quark, mediator masses up to 2.7 TeV are excluded at the 95% confidence level. Upper limits on the coupling strength are also derived.

Place, publisher, year, edition, pages
Elsevier, 2024
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-523000 (URN)10.1016/j.physletb.2023.138324 (DOI)001127436800001 ()
Funder
CERNAustralian Research CouncilDanish National Research FoundationThe Research Council of NorwaySwedish Research CouncilWallenberg FoundationsEU, European Research CouncilEuropean Regional Development Fund (ERDF)EU, Horizon 2020German Research Foundation (DFG)European Social Fund (ESF)
Note

For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2023.138324

Available from: 2024-02-14 Created: 2024-02-14 Last updated: 2024-02-14Bibliographically approved
Aad, G., Bergeås Kuutmann, E., Brenner, R., Dimitriadi, C., Ekelöf, T., Ellajosyula, V., . . . Zwalinski, L. (2024). Studies of new Higgs boson interactions through nonresonant HH production in the bb-γγ final state in pp collisions at √s=13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP) (1), Article ID 66.
Open this publication in new window or tab >>Studies of new Higgs boson interactions through nonresonant HH production in the bb-γγ final state in pp collisions at √s=13 TeV with the ATLAS detector
Show others...
2024 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 1, article id 66Article in journal (Refereed) Published
Abstract [en]

A search for nonresonant Higgs boson pair production in the final state is performed using 140 fb1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. This analysis supersedes and expands upon the previous nonresonant ATLAS results in this final state based on the same data sample. The analysis strategy is optimised to probe anomalous values not only of the Higgs (H) boson self-coupling modifier κλ but also of the quartic HHVV (V = W, Z) coupling modifier κ2V. No significant excess above the expected background from Standard Model processes is observed. An observed upper limit μHH < 4.0 is set at 95% confidence level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The 95% confidence intervals for the coupling modifiers are 1.4 < κλ < 6.9 and −0.5 < κ2V < 2.7, assuming all other Higgs boson couplings except the one under study are fixed to the Standard Model predictions. The results are interpreted in the Standard Model effective field theory and Higgs effective field theory frameworks in terms of constraints on the couplings of anomalous Higgs boson (self-)interactions.

Place, publisher, year, edition, pages
Springer, 2024
Keywords
Hadron-Hadron Scattering, Higgs Physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-524991 (URN)10.1007/JHEP01(2024)066 (DOI)001147783600001 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP01(2024)066

Available from: 2024-03-15 Created: 2024-03-15 Last updated: 2024-03-15Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Brenner, R., Dimitriadi, C., Ekelöf, T., . . . Zwalinski, L. (2023). A search for heavy Higgs bosons decaying into vector bosons in same-sign two-lepton final states in pp collisions at √s=13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP) (7), Article ID 200.
Open this publication in new window or tab >>A search for heavy Higgs bosons decaying into vector bosons in same-sign two-lepton final states 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, no 7, article id 200Article in journal (Refereed) Published
Abstract [en]

A search for heavy Higgs bosons produced in association with a vector boson and decaying into a pair of vector bosons is performed in final states with two leptons (electrons or muons) of the same electric charge, missing transverse momentum and jets. A data sample of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of 139 fb(-1). The observed data are in agreement with Standard Model background expectations. The results are interpreted using higher-dimensional operators in an effective field theory. Upper limits on the production cross-section are calculated at 95% confidence level as a function of the heavy Higgs boson's mass and coupling strengths to vector bosons. Limits are set in the Higgs boson mass range from 300 to 1500 GeV, and depend on the assumed couplings. The highest excluded mass for a heavy Higgs boson with the coupling combinations explored is 900 GeV. Limits on coupling strengths are also provided.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Higgs Physics, Hadron-Hadron Scattering, Proton-Proton Scattering
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-514953 (URN)10.1007/JHEP07(2023)200 (DOI)001061852200001 ()
Funder
EU, European Research Council
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)200

Available from: 2023-10-24 Created: 2023-10-24 Last updated: 2023-10-24Bibliographically approved
Aad, G., Bergeås Kuutmann, E., Brenner, R., Dimitriadi, C., Ekelöf, T., Ellajosyula, V., . . . Zwalinski, L. (2023). Anomaly detection search for new resonances decaying into a Higgs boson and a generic new particle X in hadronic final states using √s=13  TeV pp collisions with the ATLAS detector. Physical Review D: covering particles, fields, gravitation, and cosmology, 108(5), Article ID 052009.
Open this publication in new window or tab >>Anomaly detection search for new resonances decaying into a Higgs boson and a generic new particle X in hadronic final states using √s=13  TeV pp collisions with the ATLAS detector
Show others...
2023 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, no 5, article id 052009Article in journal (Refereed) Published
Abstract [en]

A search is presented for a heavy resonance Y decaying into a Standard Model Higgs boson H and a new particle X in a fully hadronic final state. The full Large Hadron Collider run 2 dataset of proton-proton collisions at √s=13  TeV collected by the ATLAS detector from 2015 to 2018 is used and corresponds to an integrated luminosity of 139  fb−1. The search targets the high Y-mass region, where the H and X have a significant Lorentz boost in the laboratory frame. A novel application of anomaly detection is used to define a general signal region, where events are selected solely because of their incompatibility with a learned background-only model. It is constructed using a jet-level tagger for signal-model-independent selection of the boosted X particle, representing the first application of fully unsupervised machine learning to an ATLAS analysis. Two additional signal regions are implemented to target a benchmark X decay into two quarks, covering topologies where the X is reconstructed as either a single large-radius jet or two small-radius jets. The analysis selects Higgs boson decays into b¯b, and a dedicated neural-network-based tagger provides sensitivity to the boosted heavy-flavor topology. No significant excess of data over the expected background is observed, and the results are presented as upper limits on the production cross section σ(pp→Y→XH→q¯qb¯b) for signals with mY between 1.5 and 6 TeV and mX between 65 and 3000 GeV.

Place, publisher, year, edition, pages
American Physical Society, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-520064 (URN)10.1103/PhysRevD.108.052009 (DOI)001088448300001 ()
Funder
EU, European Research Council
Note

For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.052009

Available from: 2024-01-11 Created: 2024-01-11 Last updated: 2024-01-11Bibliographically approved
Aad, G., Bergeås Kuutmann, E., Brenner, R., Dimitriadi, C., Ekelöf, T., Ellajosyula, V., . . . Zwalinski, L. (2023). ATLAS flavour-tagging algorithms for the LHC Run 2 pp collision dataset. European Physical Journal C, 83(7), Article ID 681.
Open this publication in new window or tab >>ATLAS flavour-tagging algorithms for the LHC Run 2 pp collision dataset
Show others...
2023 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, no 7, article id 681Article in journal (Refereed) Published
Abstract [en]

The flavour-tagging algorithms developed by the AvTLAS Collaboration and used to analyse its dataset of root s = 13 TeV pp collisions from Run 2 of the Large Hadron Collider are presented. These new tagging algorithms are based on recurrent and deep neural networks, and their performance is evaluated in simulated collision events. These developments yield considerable improvements over previous jet-flavour identification strategies. At the 77% b-jet identification efficiency operating point, light-jet (charm-jet) rejection factors of 170 (5) are achieved in a sample of simulated Standard Model t (t) over bar events; similarly, at a c-jet identification efficiency of 30%, a light-jet (b-jet) rejection factor of 70 (9) is obtained.

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-514297 (URN)10.1140/epjc/s10052-023-11699-1 (DOI)001062397400001 ()
Funder
EU, European Research Council
Note

For complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-023-11699-1

Available from: 2023-10-17 Created: 2023-10-17 Last updated: 2023-10-17Bibliographically approved
Aad, G., Bergeås Kuutmann, E., Brenner, R., Dimitriadi, C., Ekelöf, T., Ellajosyula, V., . . . Zwalinski, L. (2023). Calibration of the light-flavour jet mistagging efficiency of the b-tagging algorithms with Z+jets events using 139 fb-1 of ATLAS proton-proton collision data at √ˆšs=13 TeV. European Physical Journal C, 83(8), Article ID 728.
Open this publication in new window or tab >>Calibration of the light-flavour jet mistagging efficiency of the b-tagging algorithms with Z+jets events using 139 fb-1 of ATLAS proton-proton collision data at √ˆšs=13 TeV
Show others...
2023 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, no 8, article id 728Article in journal (Refereed) Published
Abstract [en]

The identification of b-jets, referred to as b-tagging, is an important part of many physics analyses in the ATLAS experiment at the Large Hadron Collider and an accurate calibration of its performance is essential for high-quality physics results. This publication describes the calibration of the light-flavour jet mistagging efficiency in a data sample of proton-proton collision events at root s = 13 TeV corresponding to an integrated luminosity of 139 fb(-1). The calibration is performed in a sample of Z bosons produced in association with jets. Due to the low mistagging efficiency for light-flavour jets, a method which uses modified versions of the b-tagging algorithms referred to as flip taggers is used in this work. A fit to the jet-flavour-sensitive secondary-vertex mass is performed to extract a scale factor from data, to correct the light-flavour jet mistagging efficiency in Monte Carlo simulations, while simultaneously correcting the b-jet efficiency. With this procedure, uncertainties coming from the modeling of jets from heavy-flavour hadrons are considerably lower than in previous calibrations of the mistagging scale factors, where they were dominant. The scale factors obtained in this calibration are consistent with unity within uncertainties.

Place, publisher, year, edition, pages
Springer, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-516559 (URN)10.1140/epjc/s10052-023-11736-z (DOI)001062397300002 ()
Funder
EU, European Research CouncilEU, Horizon 2020Swedish Research CouncilCERN
Note

For complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-023-11736-z

Available from: 2023-11-24 Created: 2023-11-24 Last updated: 2023-11-24Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Charged-hadron production in pp, p plus Pb, Pb plus Pb, and Xe plus Xe collisions at √sNN=5 TeV with the ATLAS detector at the LHC. Journal of High Energy Physics (JHEP) (7), Article ID 74.
Open this publication in new window or tab >>Charged-hadron production in pp, p plus Pb, Pb plus Pb, and Xe plus Xe collisions at √sNN=5 TeV with the ATLAS detector at the LHC
Show others...
2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 7, article id 74Article in journal (Refereed) Published
Abstract [en]

This paper presents measurements of charged-hadron spectra obtained in pp, p+Pb, and Pb+Pb collisions at root s or root s(NN) = 5.02TeV, and in Xe+Xe collisions at root s(NN) = 5.44TeV. The data recorded by the ATLAS detector at the LHC have total integrated luminosities of 25 pb(-1), 28 nb(-1), 0.50 nb(-1), and 3 mu b(-1), respectively. The nuclear modification factors RpPb and R-AA are obtained by comparing the spectra in heavy-ion and pp collisions in a wide range of charged-particle transverse momenta and pseudorapidity. The nuclear modification factor RpPb shows a moderate enhancement above unity with a maximum at p(T) approximate to 3 GeV; the enhancement is stronger in the Pb-going direction. The nuclear modification factors in both Pb+Pb and Xe+Xe collisions feature a significant, centrality-dependent suppression. They show a similar distinct p(T)-dependence with a local maximum at p(T) approximate to 2 GeV and a local minimum at p(T) approximate to 7 GeV. This dependence is more distinguishable in more central collisions. No significant eta |-dependence is found. A comprehensive comparison with several theoretical predictions is also provided. They typically describe RAA better in central collisions and in the pT range from about 10 to 100 GeV.

Place, publisher, year, edition, pages
SPRINGER, 2023
Keywords
Heavy Ion Experiments
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-516234 (URN)10.1007/JHEP07(2023)074 (DOI)001062420000001 ()
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)074

Available from: 2023-11-17 Created: 2023-11-17 Last updated: 2023-11-17Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Brenner, R., Ekelöf, T., Ellajosyula, V., . . . Zhokin, A. (2023). Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at √s=7 and 8 TeV. Journal of High Energy Physics (JHEP) (7), Article ID 213.
Open this publication in new window or tab >>Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at √s=7 and 8 TeV
Show others...
2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 7, article id 213Article in journal (Refereed) Published
Abstract [en]

A combination of measurements of the inclusive top-quark pair production cross-section performed by ATLAS and CMS in proton-proton collisions at centre-of-mass energies of 7 and 8TeV at the LHC is presented. The cross-sections are obtained using top-quark pair decays with an opposite-charge electron-muon pair in the final state and with data corresponding to an integrated luminosity of about 5 fb(-1) at root s = 7 TeV and about 20 fb(-1) at root s = 8TeV for each experiment. The combined cross-sections are determined to be 178.5 +/- 4.7 pb at root s = 7 TeV and 243.3(-5.9)(+6.0) pb at root s = 8TeV with a correlation of 0.41, using a reference top-quark mass value of 172.5 GeV. The ratio of the combined crosssections is determined to be R-8/7 = 1.363 +/- 0.032. The combined measured cross-sections and their ratio agree well with theory calculations using several parton distribution function (PDF) sets. The values of the top-quark pole mass (with the strong coupling fixed at 0.118) and the strong coupling (with the top-quark pole mass fixed at 172.5 GeV) are extracted from the combined results by fitting a next-to-next-to-leading-order plus next-to-next-to-leading-log QCD prediction to the measurements. Using a version of the NNPDF3.1 PDF set containing no top-quark measurements, the results obtained are m(t)(pole) = 173.4(-2.0)(+1.8) GeV and alpha s(m(Z)) = 0.1170(-0.0018)(+0.0021).

Place, publisher, year, edition, pages
Springer, 2023
Keywords
Hadron-Hadron Scattering, Top Physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-517632 (URN)10.1007/JHEP07(2023)213 (DOI)001058564200001 ()
Funder
EU, European Research CouncilEU, Horizon 2020Swedish Research CouncilCERNEU, European Research CouncilEU, Horizon 2020, 675440EU, Horizon 2020, 724704EU, Horizon 2020, 752730EU, Horizon 2020, 758316EU, Horizon 2020, 765710EU, Horizon 2020, 824093EU, Horizon 2020, 884104German Research Foundation (DFG), EXC 2121German Research Foundation (DFG), 390833306German Research Foundation (DFG), 400140256 - GRK2497EU, European Research Council
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)213

Available from: 2023-12-11 Created: 2023-12-11 Last updated: 2023-12-11Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Combination of searches for invisible decays of the Higgs boson using 139 fb-1 of proton-proton collision data at root s=13 TeV collected with the ATLAS experiment. Physics Letters B, 842, Article ID 137963.
Open this publication in new window or tab >>Combination of searches for invisible decays of the Higgs boson using 139 fb-1 of proton-proton collision data at root s=13 TeV collected with the ATLAS experiment
Show others...
2023 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 842, article id 137963Article in journal (Refereed) Published
Abstract [en]

Many extensions of the Standard Model predict the production of dark matter particles at the LHC. Sufficiently light dark matter particles may be produced in decays of the Higgs boson that would appear invisible to the detector. This Letter presents a statistical combination of searches for H & RARR; invisible decays where multiple production modes of the Standard Model Higgs boson are considered. These searches are performed with the ATLAS detector using 139 fb-1 of proton-proton collisions at a centre-of-mass energy of & RADIC;s = 13 TeV at the LHC. In combination with the results at & RADIC;s = 7 TeV and 8 TeV, an upper limit on the H & RARR; invisible branching ratio of 0.107 (0.077) at the 95% confidence level is observed (expected). These results are also interpreted in the context of models where the 125 GeV Higgs boson acts as a portal to dark matter, and limits are set on the scattering cross-section of weakly interacting massive particles and nucleons.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-512132 (URN)10.1016/j.physletb.2023.137963 (DOI)001023908100001 ()
Funder
CERNEU, European Research CouncilKnut and Alice Wallenberg Foundation
Note

For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2023.137963

Available from: 2023-09-25 Created: 2023-09-25 Last updated: 2023-09-25Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8204-4124

Search in DiVA

Show all publications