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2. |
- Hansen, Christina, 1984-
(author)
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A Critical Ethnography of Political Activism : Challenges Arising from Practical, Emotional and Theoretical Closeness to the Field
- 2021
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In: kritisk etnografi. - : Svenska Sällskapet för Antropologi och Geografi. - 2003-1173. ; 4:1, s. 41-55
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Journal article (peer-reviewed)abstract
- This article presents a reflective account of the research process related to my longterm ethnographic fieldwork on activism in Malmö—an important site of pro-migrant and antiracist activism in Sweden—between 2013 and 2016. Employing ethnographic methods in the field of political activism raises questions about positionality, impact, possible overidentification with the people or groups studied, and distinctions between theory and action and epistemology. Being an insider to the field geographically (as a resident of the city and neighbourhood in focus) and ideologically (leftist politics), was highly advantageous for gaining access to the field and in building trust and close communication with radical activists. At the same time, my closeness raised challenges. Examples discussed in the article are related to the academic-activist relationship with a specific focus on negotiating positions in the field, and the ethical concerns related to studying a politically charged field. These reflections aim to offer transparency in terms of the impact these aspects’ have had on my research, while at the same time being aware of the limitations of reflexivity.
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3. |
- Hansen, Christina, 1984-
(author)
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Antirasistiska Möllan är viktigare än någonsin
- 2022
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In: Dagens ETC. - : ETC. - 1652-8980. ; :2022-11-01
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Journal article (pop. science, debate, etc.)abstract
- Stadsdelen Möllevången i Malmö är en ikonisk plats i Sverige. Nu är det viktigare än någonsin att lyfta den platsen – och berättelsen om ”antirasistiska Möllan” – som ett alternativ till en nationell politisk utveckling.
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- Hansen, Christina, 1984-
(author)
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Migrants and Swedish Activists in Solidarity : Pro-Asylum Activism as a Pathway of Political Socialisation in Malmö
- 2022
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In: Nordic Journal of Migration Research. - : Helsinki University Press. - 1799-649X. ; 12:4, s. 452-468
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Journal article (peer-reviewed)abstract
- The article examines how pro-asylum activism contributes to the political socialisation of precarious migrants who become activists, and how it facilitates their social and spatial emplacement in a particular locality. Drawing on ethnographic fieldwork conducted in 2013–2016 in the city of Malmö, an important site of pro-asylum and anti-racist activism in Sweden, the article analyses how some migrants re-establish their lives by building social relationships with established local activists. These relationships help them gain the knowledge and ability to develop their own activist trajectories, form their own organisations, and dare to conduct activism in public spaces, despite being undocumented.
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- Hansen, Christina, 1984-
(author)
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“The Capital of Love” : Activists Resisting the Stigmas of Malmö through Storytelling
- 2022
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In: Antipode. - : John Wiley & Sons. - 0066-4812 .- 1467-8330. ; 54:6, s. 1760-1780
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Journal article (peer-reviewed)abstract
- This article examines the effects of an anti-racist narrative of a neighbourhood in Malmö, an important site of pro-migrant and anti-racist activism in Sweden. Drawing on ethnographic fieldwork conducted in 2013–2016, the article analyses how this narrative was constructed as an effort to challenge the “crime-due-to-immigration-discourse” otherwise associated with Malmö and supported by far-right political parties and their sympathisers in Sweden. The activists’ place-based narratives constitute attempts of commoning and of prefiguring a certain future of the city as anti-racist. This article shows how a certain narration of a place in a particular urban context enables and encourages a strong activist space, important when conducting large-scale struggles for social justice and equality.
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8. |
- Lind, Jacob, et al.
(author)
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The Impact of Temporary Residence Permits on Young Refugees’ Abilities to Build a Life in Sweden
- 2023
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In: Social Sciences. - : MDPI. - 2076-0760. ; 12:3
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Journal article (peer-reviewed)abstract
- Drawing on interviews with young refugees, 20–30 years old, mainly from Syria and Afghanistan, we discuss the effects that temporary residence permits have on their ability to build a life in Sweden. The article includes both unaccompanied and accompanied youth that at some point had been given temporary residence permits. These permits could later be renewed or turned into permanent permits if the youth fulfilled certain tough requirements. Through rich empirical data, we show how these temporal techniques of border control keep young refugees in a state where they fear deportation, which have detrimental effects for their ability to build a life in Sweden. They are not able to plan ahead and they feel forced to work although they would have preferred to study, which puts them out of sync with other young people around them, challenges their sense of agency and increases their vulnerability. Temporary residence permits severely limit the life opportunities of young refugees in Sweden, and thus hamper their ability to achieve the “migrant integration” that is expected of them.
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9. |
- Mullier, G.A., et al.
(author)
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Constraints on Higgs boson production with large transverse momentum using H →b b ¯ decays in the ATLAS detector
- 2022
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In: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 105:9
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Journal article (peer-reviewed)abstract
- This paper reports constraints on Higgs boson production with transverse momentum above 1 TeV. The analyzed data from proton-proton collisions at a center-of-mass energy of 13 TeV were recorded with the ATLAS detector at the Large Hadron Collider from 2015 to 2018 and correspond to an integrated luminosity of 136 fb-1. Higgs bosons decaying into bb¯ are reconstructed as single large-radius jets recoiling against a hadronic system and are identified by the experimental signature of two b-hadron decays. The experimental techniques are validated in the same kinematic regime using the Z→bb¯ process. The 95% confidence-level upper limit on the cross section for Higgs boson production with transverse momentum above 450 GeV is 115 fb, and above 1 TeV it is 9.6 fb. The Standard Model cross section predictions for a Higgs boson with a mass of 125 GeV in the same kinematic regions are 18.4 fb and 0.13 fb, respectively. © 2022 CERN.
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10. |
- Mullier, G.A., et al.
(author)
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Differential tt¯ cross-section measurements using boosted top quarks in the all-hadronic final state with 139 fb−1 of ATLAS data
- 2023
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In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:4
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Journal article (peer-reviewed)abstract
- Measurements of single-, double-, and triple-differential cross-sections are presented for boosted top-quark pair-production in 13 TeV proton–proton collisions recorded by the ATLAS detector at the LHC. The top quarks are observed through their hadronic decay and reconstructed as large-radius jets with the leading jet having transverse momentum (pT) greater than 500 GeV. The observed data are unfolded to remove detector effects. The particle-level cross-section, multiplied by the branching fraction and measured in a fiducial phase space defined by requiring the leading and second-leading jets to have pT > 500 GeV and pT > 350 GeV, respectively, is 331 ± 3(stat.) ± 39(syst.) fb. This is approximately 20% lower than the prediction of fb by POWHEG+PYTHIA 8 with next-to-leading-order (NLO) accuracy but consistent within the theoretical uncertainties. Results are also presented at the parton level, where the effects of top-quark decay, parton showering, and hadronization are removed such that they can be compared with fixed-order next-to-next-to-leading-order (NNLO) calculations. The parton-level cross-section, measured in a fiducial phase space similar to that at particle level, is 1.94 ± 0.02(stat.) ± 0.25(syst.) pb. This agrees with the NNLO prediction of pb. Reasonable agreement with the differential cross-sections is found for most NLO models, while the NNLO calculations are generally in better agreement with the data. The differential cross-sections are interpreted using a Standard Model effective field-theory formalism and limits are set on Wilson coefficients of several four-fermion operators.
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11. |
- Mullier, G.A., et al.
(author)
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Measurement of muon pairs produced via ?? scattering in nonultraperipheral Pb+Pb collisions at √???=5.02 TeV with the ATLAS detector
- 2023
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In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 107:5
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Journal article (peer-reviewed)abstract
- Results of a measurement of dimuon photoproduction in nonultraperipheral Pb+Pb collisions at √???=5.02 TeV are presented. The measurement uses ATLAS data from the 2015 and 2018 Pb+Pb data-taking periods at the LHC with an integrated luminosity of 1.94nb−1. The ??→?+?− pairs are identified via selections on pair momentum asymmetry and acoplanarity. Differential cross sections for dimuon production are measured in different centrality, average muon momentum, and pair rapidity intervals as functions of acoplanarity and ?⊥, the transverse momentum kick of one muon relative to the other. Measurements are also made as a function of the rapidity separation of the muons and the angle of the muon pair relative to the second-order event plane to test whether magnetic fields generated in the quark-gluon plasma affect the measured muons. A prior observation of a centrality-dependent broadening of the acoplanarity distribution is confirmed. Furthermore, the improved precision of the measurement reveals a depletion in the number of pairs having small acoplanarity or ?⊥ values in more central collisions. The acoplanarity distributions in a given centrality interval are observed to vary with the mean ?T of the muons in the pair, but the ?⊥ distributions do not. Comparisons with recent theoretical predictions are made. The predicted trends associated with effects of magnetic fields on the dimuons are not observed.
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12. |
- Mullier, G.A., et al.
(author)
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Search for flavor-changing neutral-current couplings between the top quark and the Z boson with proton-proton collisions at √s=13 TeV with the ATLAS detector
- 2023
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In: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 108:3
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Journal article (peer-reviewed)abstract
- A search for flavor-changing neutral-current couplings between a top quark, an up or charm quark, and a Z boson is presented, using proton–proton collision data at √s=13 TeV collected by the ATLAS detector at the Large Hadron Collider. The analyzed data set corresponds to an integrated luminosity of 139 fb−1. The search targets both single-top-quark events produced as gq→tZ (with q=u, c) and top-quark-pair events, with one top quark decaying through the t→Zq channel. The analysis considers events with three leptons (electrons or muons), a b-tagged jet, possible additional jets, and missing transverse momentum. The data are found to be consistent with the background-only hypothesis and 95% confidence-level limits on the t→Zq branching ratios, assuming only tensor operators of the Standard Model effective field theory framework contribute to the tZq vertices. These are 6.2×10−5 (13×10−5) for t→Zu (t→Zc) for a left-handed tZq coupling, and 6.6×10−5 (12×10−5) in the case of a right-handed coupling. These results are interpreted as 95% CL upper limits on the strength of the corresponding couplings, yielding limits for and and of 0.15 (0.16), and limits for and and of 0.22 (0.21), assuming a new-physics energy scale ΛNP of 1 TeV.
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13. |
- Mullier, G.A., et al.
(author)
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Search for heavy, long-lived, charged particles with large ionisation energy loss in pp collisions at √s = 13 TeV using the ATLAS experiment and the full Run 2 dataset
- 2023
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In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:6
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Journal article (peer-reviewed)abstract
- This paper presents a search for hypothetical massive, charged, long-lived particles with the ATLAS detector at the LHC using an integrated luminosity of 139 fb−1 of proton–proton collisions at √s = 13 TeV. These particles are expected to move significantly slower than the speed of light and should be identifiable by their high transverse momenta and anomalously large specific ionisation losses, dE/dx. Trajectories reconstructed solely by the inner tracking system and a dE/dx measurement in the pixel detector layers provide sensitivity to particles with lifetimes down to O(1) ns with a mass, measured using the Bethe–Bloch relation, ranging from 100 GeV to 3 TeV. Interpretations for pair-production of R-hadrons, charginos and staus in scenarios of supersymmetry compatible with these particles being long-lived are presented, with mass limits extending considerably beyond those from previous searches in broad ranges of lifetime.
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14. |
- Mullier, G.A., et al.
(author)
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Search for Heavy Neutral Leptons in Decays of W Bosons Using a Dilepton Displaced Vertex in sqrt[s]=13 TeV pp Collisions with the ATLAS Detector
- 2023
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In: Physical Review Letters. - : American Physical Society (APS). - 1079-7114 .- 0031-9007. ; 131:6
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Journal article (peer-reviewed)abstract
- A search for a long-lived, heavy neutral lepton (N) in 139 fb^{-1} of sqrt[s]=13 TeV pp collision data collected by the ATLAS detector at the Large Hadron Collider is reported. The N is produced via W→Nμ or W→Ne and decays into two charged leptons and a neutrino, forming a displaced vertex. The N mass is used to discriminate between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the N with the left-handed neutrino states for the N mass range 3 GeV
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15. |
- Mullier, G.A., et al.
(author)
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Search for high-mass Wγ and Zγ resonances using hadronic W/Z boson decays from 139 fb-1 of pp collisions at √s=13 TeV with the ATLAS detector
- 2023
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In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:7
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Journal article (peer-reviewed)abstract
- A search for high-mass charged and neutral bosons decaying to Wγ and Zγ final states is presented in this paper. The analysis uses a data sample of √s = 13 TeV proton-proton collisions with an integrated luminosity of 139 fb−1 collected by the ATLAS detector during LHC Run 2 operation. The sensitivity of the search is determined using models of the production and decay of spin-1 charged bosons and spin-0/2 neutral bosons. The range of resonance masses explored extends from 1.0 TeV to 6.8 TeV. At these high resonance masses, it is beneficial to target the hadronic decays of the W and Z bosons because of their large branching fractions. The decay products of the high-momentum W/Z bosons are strongly collimated and boosted-boson tagging techniques are employed to improve the sensitivity. No evidence of a signal above the Standard Model backgrounds is observed, and upper limits on the production cross-sections of these bosons times their branching fractions to Wγ and Zγ are derived for various boson production models.
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16. |
- Mullier, G.A., et al.
(author)
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Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in pp collisions at √s = 13 TeV with the ATLAS detector
- 2023
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In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:6
-
Journal article (peer-reviewed)abstract
- A search for light long-lived neutral particles with masses in the O(MeV–GeV) range is presented. The analysis targets the production of long-lived dark photons in the decay of a Higgs boson produced via gluon–gluon fusion or in association with a W boson. Events that contain displaced collimated Standard Model fermions reconstructed in the calorimeter or muon spectrometer are selected in 139 fb−1 of √s = 13 TeV pp collision data collected by the ATLAS detector at the LHC. Background estimates for contributions from Standard Model processes and instrumental effects are extracted from data. The observed event yields are consistent with the expected background. Exclusion limits are reported on the production cross-section times branching fraction as a function of the mean proper decay length cτ of the dark photon, or as a function of the dark-photon mass and kinetic mixing parameter that quantifies the coupling between the Standard Model and potential hidden (dark) sectors. A Higgs boson branching fraction above 1% is excluded at 95% CL for a Higgs boson decaying into two dark photons for dark-photon mean proper decay lengths between 10 mm and 250 mm and dark photons with masses between 0.4 GeV and 2 GeV.
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17. |
- Mullier, G.A., et al.
(author)
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Search for new phenomena in final states with photons, jets and missing transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector
- 2023
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In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:7
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Journal article (peer-reviewed)abstract
- A search for new phenomena has been performed in final states with at least one isolated high-momentum photon, jets and missing transverse momentum in proton–proton collisions at a centre-of-mass energy of √s = 13 TeV. The data, collected by the ATLAS experiment at the CERN LHC, correspond to an integrated luminosity of 139 fb−1. The experimental results are interpreted in a supersymmetric model in which pair-produced gluinos decay into neutralinos, which in turn decay into a gravitino, at least one photon, and jets. No significant deviations from the predictions of the Standard Model are observed. Upper limits are set on the visible cross section due to physics beyond the Standard Model, and lower limits are set on the masses of the gluinos and neutralinos, all at 95% confidence level. Visible cross sections greater than 0.022 fb are excluded and pair-produced gluinos with masses up to 2200 GeV are excluded for most of the NLSP masses investigated.
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18. |
- Mullier, G.A., et al.
(author)
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Search for resonant and non-resonant Higgs boson pair production in the bb−τ+τ- decay channel using 13TeV pp collision data from the ATLAS detector
- 2023
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In: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media Deutschland GmbH. - 1126-6708 .- 1029-8479. ; 2023:7
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Journal article (peer-reviewed)abstract
- A search for Higgs boson pair production in events with two b-jets and two τ-leptons is presented, using a proton–proton collision dataset with an integrated luminosity of 139 fb−1 collected at √s = 13 TeV by the ATLAS experiment at the LHC. Higgs boson pairs produced non-resonantly or in the decay of a narrow scalar resonance in the mass range from 251 to 1600 GeV are targeted. Events in which at least one τ-lepton decays hadronically are considered, and multivariate discriminants are used to reject the backgrounds. No significant excess of events above the expected background is observed in the non-resonant search. The largest excess in the resonant search is observed at a resonance mass of 1 TeV, with a local (global) significance of 3.1σ (2.0σ). Observed (expected) 95% confidence-level upper limits are set on the non-resonant Higgs boson pair-production cross-section at 4.7 (3.9) times the Standard Model prediction, assuming Standard Model kinematics, and on the resonant Higgs boson pair-production cross-section at between 21 and 900 fb (12 and 840 fb), depending on the mass of the narrow scalar resonance.
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