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Pavao, R. P., Liang, W. H., Nieves, J., & Oset, E. (2017). Predictions for Xi(-)(b) -> pi-(D-S(-)) Xi(0)(C) (2790) (Xi(0)(C)(2815) and Xi(-)(b) -> (v)over-bar (l)l Xi(0)(C)(2790) (Xi(0)(C)(2815). Eur. Phys. J. C, 77(4), 265–12pp.
Abstract: We have performed calculations for the non-leptonic Xi(-)(b) -> pi-(D-S(-)) Xi(0)(C) (2790)(J = 1/2) Xi(-)(b) -> pi(-) Xi(0)(C)(2815) (J = 3/2) and decays and the same reactions replacing the pi- by a D-s(-). At the same time we have also evaluated the semileptonic rates for and Xi(-)(b) -> pi-(D-S(-)) Xi(0)(C) (2790). We look at the reactions from the perspective that the Xi(0(2790))(c) and Xi(0)(c)(2815()) resonances are dynamically generated from the pseudoscalar-baryon and vector-baryon interactions. We evaluate ratios of the rates of these reactions and make predictions that can be tested in future experiments. We also find that the results are rather sensitive to the coupling of the Xi(c)* resonances to the D*Sigma and D*A components.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Measurement of jet activity produced in top-quark events with an electron, a muon and two b-tagged jets in the final state in pp collisions root s=13TeV with the ATLAS detector. Eur. Phys. J. C, 77(4), 220–38pp.
Abstract: Measurements of jet activity in top-quark pair events produced in proton-proton collisions are presented, using 3.2 fb of pp collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Events are chosen by requiring an opposite-charge pair and two b-tagged jets in the final state. The normalised differential cross-sections of top-quark pair production are presented as functions of additional-jet multiplicity and transverse momentum, . The fraction of signal events that do not contain additional jet activity in a given rapidity region, the gap fraction, is measured as a function of the threshold for additional jets, and is also presented for different invariant mass regions of the system. All measurements are corrected for detector effects and presented as particle-level distributions compared to predictions with different theoretical approaches for QCD radiation. While the kinematics of the jets from top-quark decays are described well, the generators show differing levels of agreement with the measurements of observables that depend on the production of additional jets.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Search for triboson (WWW -/+)-W-+/-W-+/- production in pp collisions at root s=8 TeV with the ATLAS detector. Eur. Phys. J. C, 77(3), 141–28pp.
Abstract: This paper reports a search for triboson (WWW -/+)-W-+/--W-+/- production in two decay channels ((WWW -/+)-W-+/--W-+/- -> l(+/-)vl(+/-)vl(-/+) v and (WWW -/+)-W-+/--W-+/- -> l(+/-)vl(+/-)vjj with l = e, mu) in proton-proton collision data corresponding to an integrated luminosity of 20.3 fb(-1) at a centre-of-mass energy of 8 TeV with the ATLAS detector at the Large Hadron Collider. Events with exactly three charged leptons, or two leptons with the same electric charge in association with two jets, are selected. The total number of events observed in data is consistent with the Standard Model (SM) predictions. The observed 95% confidence level upper limit on the (WWW -/+)-W-+/--W-+/- production cross section is found to be 730 fb with an expected limit of 560 fb in the absence of SM (WWW -/+)-W-+/--W-+/- production. Limits are also set on WWWW anomalous quartic gauge couplings.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Measurement of the prompt J/psi pair production cross-section in pp collisions at root s=8 TeV with the ATLAS detector. Eur. Phys. J. C, 77(2), 76–34pp.
Abstract: The production of two prompt J/psi mesons, each with transverse momenta p(T) > 8.5 GeV and rapidity vertical bar y vertical bar < 2.1, is studied using a sample of proton-proton collisions at root s = 8 TeV, corresponding to an integrated luminosity of 11.4 fb(-1) collected in 2012 with the ATLAS detector at the LHC. The differential cross-section, assuming unpolarised J/psi production, is measured as a function of the transverse momentum of the lower-p(T) J/psi meson, di-J/psi p(T) and mass, the difference in rapidity between the two J/psi mesons, and the azimuthal angle between the two J/psi mesons. The fraction of prompt pair events due to double parton scattering is determined by studying kinematic correlations between the two J/psi mesons. The total and double parton scattering cross-sections are compared with predictions. The effective cross-section of double parton scattering is measured to be sigma(eff) = 6.3 +/- 1.6(stat) +/- 1.0(syst) mb.
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Caputo, A., Hernandez, P., Kekic, M., Lopez-Pavon, J., & Salvado, J. (2017). The seesaw path to leptonic CP violation. Eur. Phys. J. C, 77(4), 258–7pp.
Abstract: Future experiments such as SHiP and highintensity e(+)e(-) colliders will have a superb sensitivity to heavy Majorana neutrinos with masses below M-Z. We show that the measurement of the mixing to electrons and muons of one such state could establish the existence of CP violating phases in the neutrino mixing matrix, in the context of low-scale seesaw models. We quantify in the minimal model the CP reach of these future experiments, and demonstrate that CP violating phases in the mixing matrix could be established at 5 sigma CL in a very significant fraction of parameter space.
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