|
ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Measurement of D*(+/-) meson production in jets from pp collisions at root s=7 TeV with the ATLAS detector. Phys. Rev. D, 85(5), 052005–22pp.
Abstract: This paper reports a measurement of D*(+/-) meson production in jets from proton- proton collisions at a center- of- mass energy of root s = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb(-1) for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range vertical bar eta vertical bar <2.5. D*(+/-) mesons found in jets are fully reconstructed in the decay chain: D*(+/-)-> D-0 pi(+), D-0 -> K-pi(+), and its charge conjugate. The production rate is found to be N(D*(+/-))/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*(+/-) mesons that carry a fraction z of the jet momentum in the range 0.3< z< 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.
|
|
|
ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Study of jets produced in association with a W boson in pp collisions at root s=7 TeV with the ATLAS detector. Phys. Rev. D, 85(9), 092002–40pp.
Abstract: We report a study of final states containing a W boson and hadronic jets, produced in proton-proton collisions at a center-of-mass energy of 7 TeV. The data were collected with the ATLAS detector at the CERN LHC and comprise the full 2010 data sample of 36 pb(-1). Cross sections are determined using both the electron and muon decay modes of the W boson and are presented as a function of inclusive jet multiplicity, N-jet, for up to five jets. At each multiplicity, cross sections are presented as a function of jet transverse momentum, the scalar sum of the transverse momenta of the charged lepton, missing transverse momentum, and all jets, the invariant mass spectra of jets, and the rapidity distributions of various combinations of leptons and final-state jets. The results, corrected for all detector effects and for all backgrounds such as diboson and top quark pair production, are compared with particle-level predictions from perturbative QCD. Leading-order multiparton event generators, normalized to the next-to-next-to-leading-order total cross section for inclusive W-boson production, describe the data reasonably well for all measured inclusive jet multiplicities. Next-to-leading-order calculations from MCFM, studied here for N-jet <= 2, and BLACKHAT-SHERPA, studied here for N-jet <= 4, are found to be mostly in good agreement with the data.
|
|
|
ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Search for excited leptons in proton-proton collisions at root s=7 TeV with the ATLAS detector. Phys. Rev. D, 85(7), 072003–23pp.
Abstract: The ATLAS detector is used to search for excited leptons in the electromagnetic radiative decay channel l* -> l gamma. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 2.05 fb(-1). No evidence for excited leptons is found, and limits are set on the compositeness scale Lambda as a function of the excited lepton mass m(l*). In the special case where Lambda = m(l*), excited electron and muon masses below 1.87 TeV and 1.75 TeV are excluded at 95% C.L., respectively.
|
|
|
ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Measurement of the inclusive W-+/- and Z/gamma* cross sections in the e and μdecay channels in pp collisions at root s=7 TeV with the ATLAS detector. Phys. Rev. D, 85(7), 072004–39pp.
Abstract: The production cross sections of the inclusive Drell-Yan processes W-+/- -> l nu and Z/gamma* -> ll (l = e, mu) are measured in proton-proton collisions at root s = 7 TeV with the ATLAS detector. The cross sections are reported integrated over a fiducial kinematic range, extrapolated to the full range, and also evaluated differentially as a function of the W decay lepton pseudorapidity and the Z boson rapidity, respectively. Based on an integrated luminosity of about 35 pb(-1) collected in 2010, the precision of these measurements reaches a few percent. The integrated and the differential W-+/- and Z/gamma* cross sections in the e and μchannels are combined, and compared with perturbative QCD calculations, based on a number of different parton distribution sets available at next-to-next-to-leading order.
|
|
|
ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Search for resonant WZ production in the WZ -> lvl ' l ' channel in root(s)=7 TeV pp collisions with the ATLAS detector. Phys. Rev. D, 85(11), 112012–21pp.
Abstract: A generic search is presented for a heavy particle decaying to WZ -> lvl'l' (l, l' = e, mu) final states. The data were recorded by the ATLAS detector in root s = 7 TeV pp collisions at the Large Hadron Collider and correspond to an integrated luminosity of 1.02 fb(-1). The transverse mass distribution of the selected WZ candidates is found to be consistent with the standard model expectation. Upper limits on the production cross section times branching ratio are derived using two benchmark models predicting a heavy particle decaying to a WZ pair.
|
|