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Chachamis, G., Deak, M., Hentschinski, M., Rodrigo, G., & Sabio Vera, A. (2015). Single bottom quark production in kT-factorisation. J. High Energy Phys., 09(9), 123–17pp.
Abstract: We present a study within the k(T)-factorisation scheme on single bottom quark production at the LHC. In particular, we calculate the rapidity and transverse momentum differential distributions for single bottom quark/anti-quark production. In our setup, the unintegrated gluon density is obtained from the NLx BFKL Green function whereas we included mass effects to the Lx heavy quark jet vertex. We compare our results to the corresponding distributions predicted by the usual collinear factorisation scheme. The latter were produced with Pythia 8.1.
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Clausse, A., Soto, L., & Tarifeño-Saldivia, A. (2015). Influence of the Anode Length on the Neutron Emission of a 50 J Plasma Focus: Modeling and Experiment. IEEE Trans. Plasma Sci., 43(2), 629–636.
Abstract: A comprehensive set of electric data measured in a small plasma focus (PF) device of 50 J correlated with the corresponding neutron emissions is taken as the base for developing a semiempirical model of the current sheet dynamics and the neutron yield. The model is able to explain the dependence of the neutron yield with the pressure and anode length with good accuracy, and suggests a physical interpretation of the drive parameter commonly used in PF design.
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Clement, G., & Fabbri, A. (2015). A scenario for critical scalar field collapse in AdS(3). Class. Quantum Gravity, 32(9), 095009–16pp.
Abstract: We present a family of exact solutions, depending on two parameters alpha and b (related to the scalar field strength), to the three-dimensional Einstein-scalar field equations with negative cosmological constant Lambda. For b not equal 0 these solutions reduce to the static Banados-Teitelboim-Zanelli (BTZ) family of vacuum solutions, with mass M = -alpha. For b not equal 0, the solutions become dynamical and develop a strong spacelike central singularity. The alpha < 0 solutions are black-hole like, with a global structure topologically similar to that of the BTZ black holes, and a finite effective mass. We show that the near-singularity behavior of the solutions with alpha > 0 agrees qualitatively with that observed in numerical simulations of sub-critical collapse, including the independence of the near-critical regime on the angle deficit of the spacetime. We analyze in the Lambda = 0 approximation the linear perturbations of the self-similar threshold solution, alpha = 0, and find that it has only one unstable growing mode, which qualifies it as a candidate critical solution for scalar field collapse.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fernandez Martinez, P., et al. (2015). Determination of the Ratio of b-Quark Fragmentation Fractions f(s)/f(d) in pp Collisions at root s=7 TeV with the ATLAS Detector. Phys. Rev. Lett., 115(26), 262001–18pp.
Abstract: With an integrated luminosity of 2.47 fb(-1) recorded by the ATLAS experiment at the LHC, the exclusive decays B-s(0) -> J/psi phi and B-d(0) -> J/psi K*(0) of B mesons produced in pp collisions at root s = 7 TeV are used to determine the ratio of fragmentation fractions f(s)/f(d). From the observed B-s(0) -> J/psi phi and B-d(0) -> J/psi K*(0) yields, the quantity (f(s)/f(d))[B(B-s(0) -> J/psi phi)/B(B-d(0) -> J/psi K*(0) )] is measured to be 0.199 +/- 0.004(stat) +/- 0.008(syst). Using a recent theory prediction for [B(B-s(0) -> J/psi phi)/B(B-d(0) -> J/psi K*(0))] yields (f(s)/f(d)) = 0.240 +/- 0.004(stat) +/- 0.010(syst) +/- 0.017(th). This result is based on a new approach that provides a significant improvement of the world average.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fernandez Martinez, P., et al. (2015). Measurements of the top quark branching ratios into channels with leptons and quarks with the ATLAS detector. Phys. Rev. D, 92(7), 072005–31pp.
Abstract: Measurements of the branching ratios of top quark decays into leptons and jets using events with t (t) over bar ( top antitop) pairs are reported. Events were recorded with the ATLAS detector at the LHC in pp collisions at a center-of-mass energy of 7 TeV. The collected data sample corresponds to an integrated luminosity of 4.6 fb(-1). The measured top quark branching ratios agree with the Standard Model predictions within the measurement uncertainties of a few percent.
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