Douglas Roos Fran Torres Roos (original) (raw)
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Papers by Douglas Roos Fran Torres Roos
Physics Letters B, 2012
Search for new particles decaying to ZZ using final states with leptons and jets with the ATLAS d... more Search for new particles decaying to ZZ using final states with leptons and jets with the ATLAS detector in √ s = 7 TeV proton-proton collisions Abstract A search is presented for a narrow resonance decaying to a pair of Z bosons using data corresponding to 1.02 fb −1 of integrated luminosity collected by the ATLAS experiment from pp collisions at √ s = 7 TeV. Events containing either four charged leptons ( ) or two charged leptons and two jets ( jj) are analyzed and found to be consistent with the Standard Model background expectation. Lower limits on a resonance mass are set using the Randall-Sundrum (RS1) graviton model as a benchmark. Using both and jj events, an RS1 graviton with k/m pl = 0.1 and mass between 325 and 845 GeV is excluded at 95% confidence level. In addition, the events are used to set a modelindependent fiducial cross section limit of σ fid (pp → X → ZZ) < 0.92 pb at 95% confidence level for any new sources of ZZ production with m ZZ greater than 300 GeV. arXiv:1203.0718v2 [hep-ex] 25 May 2012 1 ATLAS uses a right-handed coordinate system with its origin at the nominal interaction point (IP) in the center of the detector and the z-axis along the beam line. The x-axis points from the IP to the center of the LHC ring, and the y axis points upward. Cylindrical coordinates (R, φ) are used in the transverse plane, φ being the azimuthal angle around the beam line. The pseudorapidity is defined in terms of the polar angle θ (z = r cos θ) as η = − ln tan(θ/2). The transverse energy E T is defined as E sin θ, where E is the energy associated to the calorimeter cell or energy cluster. Similarly, p T is the momentum component transverse to the beam line. 61
Composting is nowadays a general treatment method for municipal solid waste. Compostable househol... more Composting is nowadays a general treatment method for municipal solid waste. Compostable household waste contains, together with vegetable material, varying amounts of papers and boards. In the European Union composting is regarded as one recycling method for packages and this will probably favour compostable packages, like papers and boards, in the future. Paper is made up of lignocellulose and it may contain up to 20% of lignin. Ecient degradation of papers in composting plants means that biodegradation of lignin is also needed. However, very little is known about lignin degradation by mixed microbial compost populations, although lignin degradation by white-rot fungi has been extensively studied in recent years. Organic material is converted to carbon dioxide, humus, and heat by compost microorganisms. It is assumed that humus is formed mainly from lignin. Thus, lignin is not totally mineralized during composting. The elevated temperatures found during the thermophilic phase are essential for rapid degradation of lignocellulose. Complex organic compounds like lignin are mainly degraded by thermophilic microfungi and actinomycetes. The optimum temperature for thermophilic fungi is 40±50°C which is also the optimum temperature for lignin degradation in compost. Ó
Physics Letters B, 2012
Search for new particles decaying to ZZ using final states with leptons and jets with the ATLAS d... more Search for new particles decaying to ZZ using final states with leptons and jets with the ATLAS detector in √ s = 7 TeV proton-proton collisions Abstract A search is presented for a narrow resonance decaying to a pair of Z bosons using data corresponding to 1.02 fb −1 of integrated luminosity collected by the ATLAS experiment from pp collisions at √ s = 7 TeV. Events containing either four charged leptons ( ) or two charged leptons and two jets ( jj) are analyzed and found to be consistent with the Standard Model background expectation. Lower limits on a resonance mass are set using the Randall-Sundrum (RS1) graviton model as a benchmark. Using both and jj events, an RS1 graviton with k/m pl = 0.1 and mass between 325 and 845 GeV is excluded at 95% confidence level. In addition, the events are used to set a modelindependent fiducial cross section limit of σ fid (pp → X → ZZ) < 0.92 pb at 95% confidence level for any new sources of ZZ production with m ZZ greater than 300 GeV. arXiv:1203.0718v2 [hep-ex] 25 May 2012 1 ATLAS uses a right-handed coordinate system with its origin at the nominal interaction point (IP) in the center of the detector and the z-axis along the beam line. The x-axis points from the IP to the center of the LHC ring, and the y axis points upward. Cylindrical coordinates (R, φ) are used in the transverse plane, φ being the azimuthal angle around the beam line. The pseudorapidity is defined in terms of the polar angle θ (z = r cos θ) as η = − ln tan(θ/2). The transverse energy E T is defined as E sin θ, where E is the energy associated to the calorimeter cell or energy cluster. Similarly, p T is the momentum component transverse to the beam line. 61
Composting is nowadays a general treatment method for municipal solid waste. Compostable househol... more Composting is nowadays a general treatment method for municipal solid waste. Compostable household waste contains, together with vegetable material, varying amounts of papers and boards. In the European Union composting is regarded as one recycling method for packages and this will probably favour compostable packages, like papers and boards, in the future. Paper is made up of lignocellulose and it may contain up to 20% of lignin. Ecient degradation of papers in composting plants means that biodegradation of lignin is also needed. However, very little is known about lignin degradation by mixed microbial compost populations, although lignin degradation by white-rot fungi has been extensively studied in recent years. Organic material is converted to carbon dioxide, humus, and heat by compost microorganisms. It is assumed that humus is formed mainly from lignin. Thus, lignin is not totally mineralized during composting. The elevated temperatures found during the thermophilic phase are essential for rapid degradation of lignocellulose. Complex organic compounds like lignin are mainly degraded by thermophilic microfungi and actinomycetes. The optimum temperature for thermophilic fungi is 40±50°C which is also the optimum temperature for lignin degradation in compost. Ó