ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2015). Measurements of the Nuclear Modification Factor for Jets in Pb plus Pb Collisions at root SNN=2.76 TeV with the ATLAS Detector. Phys. Rev. Lett., 114(7), 072302–18pp.
Abstract: Measurements of inclusive jet production are performed in pp and Pb + Pb collisions at root SNN = 2.76 TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 and 0.14 nb(-1), respectively. The jets are identified with the anti-k(t) algorithm with R = 0.4, and the spectra are measured over the kinematic range of jet transverse momentum 32 < pT < 500 GeV and absolute rapidity |y| < 2.1 and as a function of collision centrality. The nuclear modification factor R-AA is evaluated, and jets are found to be suppressed by approximately a factor of 2 in central collisions compared to pp collisions. The RAA shows a slight increase with pT and no significant variation with rapidity.
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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. (2015). Measurement of three-jet production cross-sections in pp collisions at 7 TeV centre-of-mass energy using the ATLAS detector. Eur. Phys. J. C, 75(5), 228–33pp.
Abstract: Double-differential three-jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of root s = 7 TeV using the ATLAS detector at the large hadron collider. The measurements are presented as a function of the three-jet mass (m(jjj)), in bins of the sum of the absolute rapidity separations between the three leading jets (|Y*|). Invariant masses extending up to 5 TeV are reached for 8 < |Y*| < 10. These measurements use a sample of data recorded using the ATLAS detector in 2011, which corresponds to an integrated luminosity of 4.51 fb(-1). Jets are identified using the anti-k(t) algorithm with two different jet radius parameters, R = 0.4 and R = 0.6. The dominant uncertainty in these measurements comes from the jet energy scale. Next-to-leading-order QCD calculations corrected to account for non-perturbative effects are compared to the measurements. Good agreement is found between the data and the theoretical predictions based on most of the available sets of parton distribution functions, over the full kinematic range, covering almost seven orders of magnitude in the measured cross-section values.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fernandez Martinez, P., Ferrer, A., et al. (2015). Search for new phenomena in events with a photon and missing transverse momentum in pp collisions at root s = 8 TeV with the ATLAS detector. Phys. Rev. D, 91(1), 012008–25pp.
Abstract: Results of a search for new phenomena in events with an energetic photon and large missing transverse momentum with the ATLAS experiment at the LHC are reported. Data were collected in proton-proton collisions at a center-of-mass energy of 8 TeVand correspond to an integrated luminosity of 20.3 fb(-1). The observed data are well described by the expected Standard Model backgrounds. The expected (observed) upper limit on the fiducial cross section for the production of events with a photon and large missing transverse momentum is 6.1 (5.3) fb at 95% confidence level. Exclusion limits are presented on models of new phenomena with large extra spatial dimensions, supersymmetric quarks, and direct pair production of dark-matter candidates.
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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. (2015). Measurement of the inclusive jet cross-section in proton-proton collisions at root s=7 TeV using 4.5 fb(-1) of data with the ATLAS detector. J. High Energy Phys., 02(2), 153–54pp.
Abstract: The inclusive jet cross-section is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using a data set corresponding to an integrated luminosity of 4.5 fb(-1) collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-k(t) algorithm with radius parameter values of 0.4 and 0.6. The double-differential cross-sections are presented as a function of the jet transverse momentum and the jet rapidity, covering jet transverse momenta from 100 GeV to 2 TeV. Next-to-leading-order QCD calculations corrected for non-perturbative effects and electroweak effects, as well as Monte Carlo simulations with next-to-leading-order matrix elements interfaced to parton showering, are compared to the measured cross-sections. A quantitative comparison of the measured cross-sections to the QCD calculations using several sets of parton distribution functions is performed.
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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. (2015). Measurement of the WW plus WZ cross section and limits on anomalous triple gauge couplings using final states with one lepton, missing transverse momentum, and two jets with the ATLAS detector at root s=7 TeV. J. High Energy Phys., 01(1), 049–42pp.
Abstract: The production of a W boson decaying to ev or μv in association with a W or Z boson decaying to two jets is studied using 4.6 fb(-1) of proton-proton collision data at root s = 7 TeV recorded with the ATLAS detector at the LHC. The combined WW + WZ cross section is measured with a significance of 3.4 sigma and is found to be 68 +/- 7 (stat.) +/- 19 (syst.) pb, in agreement with the Standard Model expectation of 61.1 +/- 2.2 pb. The distribution of the transverse momentum of the dijet system is used to set limits on anomalous contributions to the triple gauge coupling vertices and on parameters of an effective-field-theory model.
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