LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Measurement of the (B)over-bar(0)-B-0 and (B)over-bars(0)-B-s(0) production asymmetries in pp collisions at root s=7 TeV. Phys. Lett. B, 739, 218–228.
Abstract: The (B) over bar (0)-B-0 and (B) over bar (0)(s)-B-s(0) production asymmetries, A(P)(B-0) and A(P)(B-s(0)), are measured by means of a time-dependent analysis of B-0 -> J/Psi K-*0, B-0 -> D-pi(+) and B-s(0) -> D-s(-)pi(+) decays, using a data sample corresponding to an integrated luminosity of 1.0 fb(-1), collected by LHCb in pp collisions at a centre-of-mass energy of 7 TeV. The measurements are performed as a function of transverse momentum and pseudorapidity of the B-0 and B-s(0) mesons within the LHCb acceptance. The production asymmetries, integrated over p(T) and eta in the range 4 < p(T) < 30 GeV/c and 2.5 < eta < 4.5, are determined to be A(P)(B-0) = (-0.35 +/- 0.76 +/- 0.28)% and A(P)(B-s(0)) = (1.09 +/- 2.61 +/- 0.66)%, where the first uncertainties are statistical and the second systematic.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fassi, F., Ferrer, A., et al. (2014). Measurement of inclusive jet charged-particle fragmentation functions in Pb plus Pb collisions at root S-NN=2.76 TeV with the ATLAS detector. Phys. Lett. B, 739, 320–342.
Abstract: Measurements of charged-particle fragmentation functions of jets produced in ultra-relativistic nuclear collisions can provide insight into the modification of parton showers in the hot, dense medium created in the collisions. ATLAS has measured jets in root S-NN = 2.76 TeV Pb+Pb collisions at the LHC using a data set recorded in 2011 with an integrated luminosity of 0.14 nb(-1). Jets were reconstructed using the anti-k(t) algorithm with distance parameter values R = 0.2, 0.3, and 0.4. Distributions of charged-particle transverse momentum and longitudinal momentum fraction are reported for seven bins in collision centrality for R = 0.4 jets with p(T)(jet) > 100 GeV. Commensurate minimum p(T) values are used for the other radii. Ratios of fragment distributions in each centrality bin to those measured in the most peripheral bin are presented. These ratios show a reduction of fragment yield in central collisions relative to peripheral collisions at intermediate z values, 0.04 less than or similar to z less than or similar to 0.2, and an enhancement in fragment yield for z less than or similar to 0.04. A smaller, less significant enhancement is observed at large z and large p(T) in central collisions.
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Chachamis, G., Hentschinski, M., Madrigal Martinez, J. D., & Sabio Vera, A. (2014). Forward jet production and quantum corrections to the gluon Regge trajectory from Lipatov's high energy effective action. Phys. Part. Nuclei, 45(4), 788–799.
Abstract: We review Lipatov's high energy effective action and show that it is a useful computational tool to calculate scattering amplitudes in (quasi)-multi-Regge kinematics. We explain in some detail our recent work where a novel regularization and subtraction procedure has been proposed that allows to extend the use of this effective action beyond tree level. Two examples are calculated at next-to-leading order: forward jet vertices and the gluon Regge trajectory.
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Tarifeño-Saldivia, A., & Soto, L. (2014). Effects of gas chamber geometry and gas flow on the neutron production in a fast plasma focus neutron source. Plasma Phys. Control. Fusion, 56(12), 125013–5pp.
Abstract: This work reports that gas chamber geometry and gas flow management substantially affect the neutron production of a repetitive fast plasma focus. The gas flow rate is the most sensitive parameter. An appropriate design of the gas chamber combined with a suitable flow-rate management can lead to improvements in the neutron production of one order of magnitude working in a fast repetitive mode.
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Pich, A. (2014). Precision tau physics. Prog. Part. Nucl. Phys., 75, 41–85.
Abstract: Precise measurements of the lepton properties provide stringent tests of the Standard Model and accurate determinations of its parameters. We overview the present status of tau physics, highlighting the most recent developments, and discuss the prospects for future improvements. The leptonic decays of the tau lepton probe the structure of the weak currents and the universality of their couplings to the W boson. The universality of the leptonic Z couplings has also been tested through Z -> l(+)l(-) decays. The hadronic tau decay modes constitute an ideal tool for studying low-energy effects of the strong interaction in very clean conditions. Accurate determinations of the QCD coupling and the Cabibbo mixing V-us have been obtained with tau data. The large mass of the tau opens the possibility to study many kinematically-allowed exclusive decay modes and extract relevant dynamical information. Violations of flavour and CP conservation laws can also be searched for with tau decays. Related subjects such as μdecays, the electron and muon anomalous magnetic moments, neutrino mixing and B-meson decays into tau leptons are briefly covered. Being one the fermions most strongly coupled to the scalar sector, the tau lepton is playing now a very important role at the LHC as a tool to test the Higgs properties and search for new physics at higher scales.
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