Browsing by Author "Maio, Am\'elia"
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- Combination of inclusive and differential $ \mathrm{t}\overline{\mathrm{t}} $ charge asymmetry measurements using ATLAS and CMS data at $ \sqrt{s}=7 $ and 8 TeVPublication . ATLAS, CMS collaboration (5098 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Mui\~no, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Oleiro Seabra, Luis Filipe; Onofre, Ant\'onio; Pedro, Rute; Santos, Helena; Saraiva, Jo\~ao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, Helmut; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Senghi Soares, Mara; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, PasqualeThis paper presents combinations of inclusive and differential measurements of the charge asymmetry (A$_{C}$) in top quark pair $ \left(\mathrm{t}\overline{\mathrm{t}}\right) $ events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. The data correspond to integrated luminosities of about 5 and 20 fb$^{−1}$ for each experiment, respectively. The resulting combined LHC measurements of the inclusive charge asymmetry are A$_{C}^{CHC7}$ = 0.005 ± 0.007 (stat) ± 0.006(syst) at 7 TeV and A$_{C}^{CHC8}$ = 0.0055 ± 0.0023 (stat) ± 0.0025 (syst) at 8 TeV. These values, as well as the combination of A$_{C}$ measurements as a function of the invariant mass of the $ \mathrm{t}\overline{\mathrm{t}} $ system at 8 TeV, are consistent with the respective standard model predictions.
- Measurement of $\chi_{c1}$ and $\chi_{c2}$ production with $\sqrt{s}$ = 7 TeV $pp$ collisions at ATLASPublication . ATLAS collaboration (2932 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Cantrill, Robert; Carvalho, Joao; Castro, Nuno Filipe; Conde Muino, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Do Valle Wemans, Andr\'e; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Lopes, Lourenco; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Marques, Carlos; Oliveira, Miguel Alfonso; Onofre, Ant\'onio; Palma, Alberto; Pedro, Rute; Pina, Joao Antonio; Pinto, Belmiro; Santos, Helena; Saraiva, Joao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutThe prompt and non-prompt production cross-sections for the chi_c1 and chi_c2 charmonium states are measured in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector at the LHC using 4.5 fb^-1 of integrated luminosity. The chi_c states are reconstructed through the radiative decay chi_c -> J/psi gamma (with J/psi -> mu+mu-) where photons are reconstructed from gamma -> e+e- conversions. The production rate of the chi_c2 state relative to the chi_c1 state is measured for prompt and non-prompt chi_c as a function of J/psi transverse momentum. The prompt chi_c cross-sections are combined with existing measurements of prompt J/psi production to derive the fraction of prompt J/psi produced in feed-down from chi_c decays. The fractions of chi_c1 and chi_c2 produced in b-hadron decays are also measured.
- Search for $W' \rightarrow tb$ decays in the hadronic final state using pp collisions at $\sqrt{s}=13$ TeV with the ATLAS detectorPublication . ATLAS collaboration (2879 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Mui\~no, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Dias do Vale, Tiago; Faisca Rodrigues Pereira, Rui Miguel; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Oleiro Seabra, Luis Filipe; Onofre, Ant\'onio; Pedro, Rute; Pereira Peixoto, Ana Paula; Santos, Helena; Saraiva, Jo\~ao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutA 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.
- Search for a Structure in the $B^0_s \pi^\pm$ Invariant Mass Spectrum with the ATLAS ExperimentPublication . ATLAS collaboration (2887 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Mui\~no, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Oleiro Seabra, Luis Filipe; Onofre, Ant\'onio; Pedro, Rute; Santos, Helena; Saraiva, Jo\~ao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutA search for the narrow structure, X(5568), reported by the D0 Collaboration in the decay sequence X→Bs0π±, Bs0→J/ψϕ, is presented. The analysis is based on a data sample recorded with the ATLAS detector at the LHC corresponding to 4.9 fb-1 of pp collisions at 7 TeV and 19.5 fb-1 at 8 TeV. No significant signal was found. Upper limits on the number of signal events, with properties corresponding to those reported by D0, and on the X production rate relative to Bs0 mesons, ρX, were determined at 95% confidence level. The results are N(X)<382 and ρX<0.015 for Bs0 mesons with transverse momenta above 10 GeV, and N(X)<356 and ρX<0.016 for transverse momenta above 15 GeV. Limits are also set for potential Bs0π± resonances in the mass range 5550 to 5700 MeV.
- Search for electroweak production of supersymmetric particles in final states with two or three leptons at $\sqrt{s}=13\,$TeV with the ATLAS detectorPublication . ATLAS collaboration (2880 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Mui\~no, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Oleiro Seabra, Luis Filipe; Onofre, Ant\'onio; Pedro, Rute; Santos, Helena; Saraiva, Jo\~ao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutA search for the electroweak production of charginos, neutralinos and sleptons decaying into final states involving two or three electrons or muons is presented. The analysis is based on 36.1 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton--proton collisions recorded by the ATLAS detector at the Large Hadron Collider. Several scenarios based on simplified models are considered. These include the associated production of the next-to-lightest neutralino and the lightest chargino, followed by their decays into final states with leptons and the lightest neutralino via either sleptons or Standard Model gauge bosons; direct production of chargino pairs, which in turn decay into leptons and the lightest neutralino via intermediate sleptons; and slepton pair production, where each slepton decays directly into the lightest neutralino and a lepton. No significant deviations from the Standard Model expectation are observed and stringent limits at 95% confidence level are placed on the masses of relevant supersymmetric particles in each of these scenarios. For a massless lightest neutralino, masses up to 580 GeV are excluded for the associated production of the next-to-lightest neutralino and the lightest chargino, assuming gauge-boson mediated decays, whereas for slepton-pair production masses up to 500 GeV are excluded assuming three generations of mass-degenerate sleptons.
- Search for Higgs boson decays to beyond-the-Standard-Model light bosons in four-lepton events with the ATLAS detector at $\sqrt{s}=13$ TeVPublication . ATLAS collaboration (2900 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Mui\~no, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Oleiro Seabra, Luis Filipe; Onofre, Ant\'onio; Pedro, Rute; Santos, Helena; Saraiva, Jo\~ao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutA search is conducted for a new beyond-the-Standard-Model boson using events where a Higgs boson with mass 125 GeV decays to four leptons ($\ell =$ $e$ or $\mu$). This decay is presumed to occur via an intermediate state which contains one or two on-shell, promptly decaying bosons: $H\rightarrow ZX/XX \rightarrow 4\ell$, where $X$ is a new vector boson $Z_d$ or pseudoscalar $a$ with mass between 1 and 60 GeV. The search uses $pp$ collision data collected with the ATLAS detector at the LHC with an integrated luminosity of 36.1 fb$^{-1}$ at a centre-of-mass energy $\sqrt{s}=13$ TeV. No significant excess of events above Standard Model background predictions is observed; therefore, upper limits at 95% confidence level are set on model-independent fiducial cross-sections, and on the Higgs boson decay branching ratios to vector and pseudoscalar bosons in two benchmark models.
- Search for High-Mass Resonances Decaying to $\tau\nu$ in pp Collisions at $\sqrt{s}$=13 TeV with the ATLAS DetectorPublication . ATLAS collaboration (2899 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Mui\~no, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Dias do Vale, Tiago; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Oleiro Seabra, Luis Filipe; Onofre, Ant\'onio; Pedro, Rute; Pereira Peixoto, Ana Paula; Santos, Helena; Saraiva, Jo\~ao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutA 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.
- Search for photonic signatures of gauge-mediated supersymmetry in 13 TeV $pp$ collisions with the ATLAS detectorPublication . ATLAS collaboration (2874 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Mui\~no, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Dias do Vale, Tiago; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Oleiro Seabra, Luis Filipe; Onofre, Ant\'onio; Pedro, Rute; Pereira Peixoto, Ana Paula; Santos, Helena; Saraiva, Jo\~ao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutA search is presented for photonic signatures, motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of proton-proton collision data at s=13 TeV corresponding to an integrated luminosity of 36.1 fb-1 recorded by the ATLAS detector at the LHC, and it explores models dominated by both strong and electroweak production of supersymmetric partner states. Experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon or additional jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction, and 95% confidence-level upper limits of between 0.083 and 0.32 fb are set on the visible cross section of contributions from physics beyond the Standard Model. These results are interpreted in terms of lower limits on the masses of gluinos, squarks, and gauginos in the context of generalized models of gauge-mediated supersymmetry, which reach as high as 2.3 TeV for strongly produced and 1.3 TeV for weakly produced supersymmetric partner pairs.
- Search for the Decay of the Higgs Boson to Charm Quarks with the ATLAS ExperimentPublication . ATLAS collaboration (2870 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Mui\~no, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gon\c calo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Am\'elia; Maneira, Jos\'e; Oleiro Seabra, Luis Filipe; Onofre, Ant\'onio; Pedro, Rute; Santos, Helena; Saraiva, Jo\~ao; Silva, Jos\'e; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutA direct search for the standard model Higgs boson decaying to a pair of charm quarks is presented. Associated production of the Higgs and Z bosons, in the decay mode ZH→ℓ+ℓ-cc¯ is studied. A data set with an integrated luminosity of 36.1 fb-1 of pp collisions at s=13TeV recorded by the ATLAS experiment at the LHC is used. The H→cc¯ signature is 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.