Browsing by Issue Date, starting with "2018-01-10"
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- Azimuthal anisotropy of charged particles with transverse momentum up to 100 GeV/ c in PbPb collisions at $\sqrt {s}_{{NN}}$=5.02 TeVPublication . CMS collaboration (2229 authors); Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Calpas, Betty; Di Francesco, Agostino; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Rodrigues Antunes, Joao; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, Pasquale; Pela, JoaoThe Fourier coefficients v2 and v3 characterizing the anisotropy of the azimuthal distribution of charged particles produced in PbPb collisions at sNN=5.02 TeV are measured with data collected by the CMS experiment. The measurements cover a broad transverse momentum range, 110 GeV/c range, where anisotropic azimuthal distributions should reflect the path-length dependence of parton energy loss in the created medium. Results are presented in several bins of PbPb collision centrality, spanning the 60% most central events. The v2 coefficient is measured with the scalar product and the multiparticle cumulant methods, which have different sensitivities to initial-state fluctuations. The values from both methods remain positive up to pT∼60–80 GeV/c , in all examined centrality classes. The v3 coefficient, only measured with the scalar product method, tends to zero for pT≳20 GeV/c . Comparisons between theoretical calculations and data provide new constraints on the path-length dependence of parton energy loss in heavy ion collisions and highlight the importance of the initial-state fluctuations.
- Relatório de Estágio Curricular: Odisseias Puras, S.APublication . Oliveira, Filipa Gonçalves Nery; Leal, Maria do CarmoO presente relatório foi redigido no contexto da conclusão do Mestrado de Marketing Digital da Universidade Europeia – Laureate International Universities, com o intuito de especificar as atividades desenvolvidas ao longo de três meses de estágio, orientado por Tiago Guerra, Diretor de Experiências, na empresa Odisseias Puras, S.A, localizada em Oeiras. O Relatório encontra-se repartido em dez diferentes capítulos teóricos, designadamente, Influência das Novas Tecnologias na Sociedade e no Marketing, Marketing Digital, Comunicação Digital, Marketing Relacional, Inbound Marketing e, por fim, Marketing de Conteúdo. Os conhecimentos teóricos que neste documento constam encontram-se inerentemente ligados às principais atividades da empresa, tendo sido esse o critério de escolha aquando da seleção dos conteúdos a serem descritos. Posteriormente, consta o capítulo final no qual é feita uma apresentação da empresa, das atividades desempenhadas durante o estágio curricular bem como de propostas de melhoria.
- Design and characterization of the readout ASIC for the BESIII CGEM detectorPublication . Cossio, Fabio; Alexeev, Maxim; Bugalho, Ricardo; Chai, Junying; Cheng, Weishuai; Da Rocha Rolo, Manuel Dionisio; Di Francesco, Agostino; Greco, Michela; Leng, Chongyang; Li, Huaishen; Maggiora, Marco; Marcello, Simonetta; Mignone, Marco; Rivetti, Angelo; Varela, Joao; Wheadon, RichardTIGER (Turin Integrated Gem Electronics for Readout) is a mixed-mode ASIC for the readout of signals from CGEM (Cylindrical Gas Electron Multiplier) detector in the upgraded inner tracker of the BESIII experiment, carried out at BEPCII in Beijing. The ASIC includes 64 channels, each of which features a dual-branch architecture optimized for timing and energy measurement. The input signal time-of-arrival and charge measurement is provided by low-power TDCs, based on analogue interpolation techniques, and Wilkinson ADCs, with a fully-digital output. The silicon results of TIGER first prototype are presented showing its full functionality.
- Measurements of $t\bar{t}$ cross sections in association with $b$ jets and inclusive jets and their ratio using dilepton final states in pp collisions at $\sqrt{s}$ = 13 TeVPublication . CMS collaboration (2197 authors); Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Calpas, Betty; Di Francesco, Agostino; Faccioli, Pietro; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, Pasquale; Pela, JoaoThe cross sections for the production of tt¯bb¯ and tt¯jj events and their ratio σtt¯bb¯/σtt¯jj are measured using data corresponding to an integrated luminosity of 2.3 fb −1 collected in pp collisions at s=13 TeV with the CMS detector at the LHC. Events with two leptons (e or μ ) and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected. In the full phase space, the measured ratio is 0.022±0.003(stat)±0.006(syst) , the cross section σtt¯bb¯ is 4.0±0.6(stat)±1.3(syst) pb and σtt¯jj is 184±6(stat)±33(syst) pb . The measurements are compared with the standard model expectations obtained from a powheg simulation at next-to-leading-order interfaced with pythia .
- Measurement of differential cross sections of isolated-photon plus heavy-flavour jet production in pp collisions at $\sqrt{s}=8$ TeV using the ATLAS detectorPublication . ATLAS collaboration (2885 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Muiño, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gonçalo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Amélia; Maneira, José; Oleiro Seabra, Luis Filipe; Onofre, António; Pedro, Rute; Santos, Helena; Saraiva, João; Silva, José; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutThis 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
- Search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a $Z$ boson in $pp$ collisions at $\sqrt{s} =$ 13 TeV with the ATLAS detectorPublication . ATLAS collaboration (2896 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Castro, Nuno Filipe; Conde Muiño, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gonçalo, Ricardo; Jorge, Pedro; Machado Miguens, Joana; Maio, Amélia; Maneira, José; Oleiro Seabra, Luis Filipe; Onofre, António; Pedro, Rute; Santos, Helena; Saraiva, João; Silva, José; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutA 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 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 mH=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.