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- Searches for scalar leptoquarks in pp collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detectorPublication . ATLAS collaboration (2865 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Cantrill, Robert; Carvalho, João; Castro, Nuno Filipe; Conde Muiño, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gonçalo, Ricardo; Jorge, Pedro; Lopes, Lourenco; Machado Miguens, Joana; Maio, Amélia; Maneira, José; Onofre, António; Palma, Alberto; Pedro, Rute; Pina, João Antonio; Santos, Helena; Saraiva, João; Silva, José; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutSearches for pair-produced scalar leptoquarks are performed using 20 fb$^{-1}$ of proton–proton collision data provided by the LHC and recorded by the ATLAS detector at $\sqrt{s}=8$ TeV. Events with two electrons (muons) and two or more jets in the final state are used to search for first (second)-generation leptoquarks. The results from two previously published ATLAS analyses are interpreted in terms of third-generation leptoquarks decaying to $b\nu _{\tau }\bar{b}\bar{\nu _{\tau }}$ and $t\nu _{\tau }\bar{t}\bar{\nu _{\tau }}$ final states. No statistically significant excess above the Standard Model expectation is observed in any channel and scalar leptoquarks are excluded at 95 % CL with masses up to $m_{\mathrm {LQ1}}<$ 1050 GeV for first-generation leptoquarks, $m_{\mathrm {LQ2}}<$ 1000 GeV for second-generation leptoquarks, $m_{\mathrm {LQ3}}<$ 625 GeV for third-generation leptoquarks in the $b\nu _{\tau }\bar{b}\bar{\nu _{\tau }}$ channel, and 200 $< m_{\mathrm {LQ3}}< $ 640 GeV in the $t\nu _{\tau }\bar{t}\bar{\nu _{\tau }}$ channel.
- Study of the $B_c^+ \rightarrow J/\psi D_s^+$ and $B_c^+ \rightarrow J/\psi D_s^{*+}$ decays with the ATLAS detectorPublication . ATLAS collaboration (2836 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Cantrill, Robert; Carvalho, João; Castro, Nuno Filipe; Conde Muiño, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gonçalo, Ricardo; Jorge, Pedro; Lopes, Lourenco; Machado Miguens, Joana; Maio, Amélia; Maneira, José; Onofre, António; Palma, Alberto; Pedro, Rute; Pina, João Antonio; Pinto, Belmiro; Santos, Helena; Saraiva, João; Silva, José; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutThe decays $B_c^+ \rightarrow J/\psi D_s^+$ and $B_c^+ \rightarrow J/\psi D_s^{*+}$ are studied with the ATLAS detector at the LHC using a dataset corresponding to integrated luminosities of 4.9 and 20.6 fb$^{-1}$ of pp collisions collected at centre-of-mass energies $\sqrt{s} = 7$ TeV and 8 TeV, respectively. Signal candidates are identified through $J/\psi \rightarrow \mu ^+\mu ^-$ and $D_s^{(*)+}\rightarrow \phi \pi ^+(\gamma /\pi ^0)$ decays. With a two-dimensional likelihood fit involving the $B_c^+$ reconstructed invariant mass and an angle between the $\mu ^+$ and $D_s^+$ candidate momenta in the muon pair rest frame, the yields of $B_c^+ \rightarrow J/\psi D_s^+$ and $B_c^+ \rightarrow J/\psi D_s^{*+}$ , and the transverse polarisation fraction in $B_c^+ \rightarrow J/\psi D_s^{*+}$ decay are measured. The transverse polarisation fraction is determined to be $\Gamma _{\pm \pm }(B_c^+ \rightarrow J/\psi D_s^{*+})/\Gamma (B_c^+ \rightarrow J/\psi D_s^{*+}) = 0.38 \pm 0.23 \pm 0.07$ , and the derived ratio of the branching fractions of the two modes is $\mathcal {B}_{B_c^+ \rightarrow J/\psi D_s^{*+}}/\mathcal {B}_{B_c^+ \rightarrow J/\psi D_s^+} = 2.8 \,^{+1.2-0.8} \pm 0.3$ , where the first error is statistical and the second is systematic. Finally, a sample of $B_c^+\rightarrow J/\psi \pi ^+$ decays is used to derive the ratios of branching fractions $\mathcal {B}_{B_c^+ \rightarrow J/\psi D_s^+}/\mathcal {B}_{B_c^+ \rightarrow J/\psi \pi ^+} = 3.8 \pm 1.1 \pm 0.4 \pm 0.2$ and $\mathcal {B}_{B_c^+ \rightarrow J/\psi D_s^{*+}}/\mathcal {B}_{B_c^+ \rightarrow J/\psi \pi ^+} = 10.4 \pm 3.1 \pm 1.5 \pm 0.6$ , where the third error corresponds to the uncertainty of the branching fraction of $D_s^+\rightarrow \phi (K^+K^-)\pi ^+$ decay. The available theoretical predictions are generally consistent with the measurement.
- Measurements of the Higgs boson production and decay rates and coupling strengths using pp collision data at $\sqrt{s}=7$ and 8 TeV in the ATLAS experimentPublication . ATLAS collaboration (2827 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Cantrill, Robert; Carvalho, João; Castro, Nuno Filipe; Conde Muiño, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gonçalo, Ricardo; Jorge, Pedro; Lopes, Lourenco; Machado Miguens, Joana; Maio, Amélia; Maneira, José; Onofre, António; Palma, Alberto; Pedro, Rute; Pina, João Antonio; Pinto, Belmiro; Santos, Helena; Saraiva, João; Silva, José; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, HelmutCombined analyses of the Higgs boson production and decay rates as well as its coupling strengths to vector bosons and fermions are presented. The combinations include the results of the analyses of the $H\rightarrow \gamma \gamma ,\, ZZ^*,\, WW^*,\, Z\gamma ,\, b\bar{b},\, \tau \tau $ and $\mu \mu $ decay modes, and the constraints on the associated production with a pair of top quarks and on the off-shell coupling strengths of the Higgs boson. The results are based on the LHC proton-proton collision datasets, with integrated luminosities of up to 4.7 $\mathrm {fb}^{-1}$ at $\sqrt{s}=7$ TeV and 20.3 $\mathrm {fb}^{-1}$ at $\sqrt{s}=8$ TeV, recorded by the ATLAS detector in 2011 and 2012. Combining all production modes and decay channels, the measured signal yield, normalised to the Standard Model expectation, is $1.18^{+0.15-0.14}$ . The observed Higgs boson production and decay rates are interpreted in a leading-order coupling framework, exploring a wide range of benchmark coupling models both with and without assumptions on the Higgs boson width and on the Standard Model particle content in loop processes. The data are found to be compatible with the Standard Model expectations for a Higgs boson at a mass of 125.36 GeV for all models considered.
- SNO+ status and plans for double beta decay search and other neutrino studiesPublication . Andringa, S.SNO+ is a multi-purpose Neutrino Physics experiment, succeeding to the Sudbury Neutrino Observatory by replacing heavy water with liquid scintillator, which can also be loaded with large quantities of double-beta decaying isotope. The scientific goals of SNO+ are the search for neutrinoless double-beta decay, the study of solar neutrinos and of anti-neutrinos from nuclear reactors and the Earth's natural radioactivity, as well as supernovae neutrinos. The installation of the detector at SNOLAB is being completed and commissioning has already started with a dry run. The detector will soon be filled with water and, later, with scintillator. Here we highlight the main detector developments and address the several Physics analysis being prepared for the several planned SNO+ runs.