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Campanario, F., Rauch, M., & Sapeta, S. (2014). W+W- production at high transverse momenta beyond NLO. Nucl. Phys. B, 879, 65–79.
Abstract: Pair production of W gauge bosons is an important process at the LHC entering many experimental analyses, both as background in new-physics searches or Higgs measurements and as signal in precision studies and tests of the Standard Model. Therefore, accurate predictions for this class of processes are of great interest in order to exploit the full potential of LHC measurements. We use the LoopSim method to combine NLO QCD results for WW and WW + jet, as well as the loop-squared gluon-fusion contribution, to obtain approximate NNLO predictions for WW production. The cross sections are calculated with VBFNLO and include leptonic decays of the W bosons as well as finite-width and off-shell effects. We find that the size of the additional corrections beyond NLO can be significant and well outside of the NLO error bands given by renormalization and factorization scale variation. Applying a jet veto, we observe further negative corrections at NNLO. which we relate to the presence of large Sudakov logarithms.
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Bayar, M., Liang, W. H., Uchino, T., & Xiao, C. W. (2014). Description of rho(1700) as a rho Kappa(sic) system with the fixed-center approximation. Eur. Phys. J. A, 50(4), 67–10pp.
Abstract: We study the system with the aim to describe the rho(1700) resonance. The chiral unitary approach has achieved success in the description of systems of the light hadron sector. With this method, the system in the isospin sector I = 0, is found to be a dominant component of the f (0)(980) resonance. Therefore, by regarding the system as a cluster, the f (0)(980) resonance, we evaluate the system applying the fixed-center approximation to the Faddeev equations. We construct the rho K unitarized amplitude using the chiral unitary approach. As a result, we find a peak in the three-body amplitude around 1732 MeV and a width of about 161 MeV. The effect of the width of the rho and f (0)(980) is also discussed. We associate this peak to the rho(1700) which has a mass of 1720 +/- 20MeV and a width of 250 +/- 100 MeV.
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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 the production of a W boson in association with a charm quark in pp collisions at root s=7 TeV with the ATLAS detector. J. High Energy Phys., 05(5), 068–67pp.
Abstract: The production of a W boson in association with a single charm quark is studied using 4.6 fb(-1) of pp collision data at root s = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96(-0.30)(+0.26) at Q (2) = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio sigma(W (+) +)/sigma(W (-) + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s-(s) over bar quark asymmetry.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2014). Search for the Standard Model Higgs boson decay to mu(+)mu(-) with the ATLAS detector. Phys. Lett. B, 738, 68–86.
Abstract: A search is reported for Higgs boson decay to mu(+)mu(-) using data with an integrated luminosity of 24.8 fb(-1) collected with the ATLAS detector in pp collisions at root s = 7 and 8 TeV at the CERN Large Hadron Collider. The observed dimuon invariant mass distribution is consistent with the Standard Model background-only hypothesis in the 120-150 GeV search range. For a Higgs boson with a mass of 125.5 GeV, the observed (expected) upper limit at the 95% confidence level is 7.0 (7.2) times the Standard Model expectation. This corresponds to an upper limit on the branching ratio BR(H -> mu(+)mu(-)) of 1.5 x10(-3).
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Measurement of polarization amplitudes and CP asymmetries in B-0 -> phi K*(892)(0). J. High Energy Phys., 05(5), 069–24pp.
Abstract: An angular analysis of the decay B (0) -> phi K (*)(892)(0) is reported based on a pp collision data sample, corresponding to an integrated luminosity of 1.0 fb(-1), collected at a centre-of-mass energy of root S = 7 TeV with the LHCb detector. The P-wave amplitudes and phases are measured with a greater precision than by previous experiments, and confirm about equal amounts of longitudinal and transverse polarization. The S-wave K+ pi(-) and K+ K- contributions are taken into account and found to be significant. A comparison of the B (0) -> phi K (*)(892)(0) and results shows no evidence for direct CP violation in the rate asymmetry, in the triple-product asymmetries or in the polarization amplitudes and phases.
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