Measurement of the inclusive jet cross section in p(p)over-bar collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Model indedpendent search for new phenomena in p(p)over-bar collisions at root s=1.96 TeV

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tratamento de águas residuárias de suinocultura em reatores anaeróbios horizontais seguidos de reator aeróbio em batelada sequencial

Avaliou-se o desempenho de um sistema combinado anaeróbio-aeróbio para o tratamento de águas residuárias de suinocultura, com concentrações médias de sólidos suspensos totais (SST) de 18.624 e 11.395 mg L-1. Foram utilizados quatro reatores anaeróbios horizontais com volume total de 49,5 L cada, um com manta de lodo (RAHML) e três de leito fixo (RAHLF), instalados em série e seguidos de um reator aeróbio operado em batelada sequencial (RBS) com volume total de 339 L e com alimentação contínua. Nos RAHLF, foram utilizados como meios suporte de anéis de bambu, anéis plásticos de eletroduto corrugado e anéis de bucha (Luffa cillyndrica), respectivamente. Os tempos de detenção hidráulica (TDH) e as cargas orgânicas volumétricas (COV) aplicadas no RAHML foram de 12 e 10 h e 53 e 61 g DQO (L d)-1, respectivamente. O RBS foi operado com ciclo de 24 h e COV de 0,34 e 0,50 g DQO (L d)-1. As eficiências médias de remoção de DQOtotal e SST para o conjunto de reatores anaeróbios horizontais, em série, foram de 96 e 99%, e de 96 e 95%, respectivamente. As maiores produções volumétricas de metano ocorreram nos RAHLF, com valores médios de até 0,744 m³ CH4 (m³ reator d)-1. A inclusão do RBS permitiu melhorar a qualidade do efluente e a estabilidade do sistema de tratamento, atingindo eficiências de remoção de DQOtotal e SST de 99 e 99%, e de 98 e 99%, respectivamente. No RBS, ocorreu nitrificação e desnitrificação, com remoções de N-amoniacal de até 65%.

Measurement of the differential cross section d sigma/dt in elastic p(p)over-bar scattering at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for the flavor-changing neutral current decay Bs 0 → μ+ μ- pp̄ Collisions at √s = 1.96 TeV with the DO Detector

We present the results of a search for the flavor-changing neutral current decay Bs 0 → μ+ μ-. using a data set with integrated luminosity of 240 pb-1 of pp̄ collisions at √s = 1.96 TeV collected with the D0 detector in run II of the Fermilab Tevatron collider. We find the upper limit on the branching fraction to be B(Bs 0 → μ+ π-) ≤ 5.0 × 10-7 at the 95% C.L. assuming no contributions from the decay Bd 0 → μ+ μ- in the signal region. This limit is the most stringent upper bound on the branching fraction Bs 0 → μ+ μ- to date. © 2005 The American Physical Society.

Measurement of the pp(-)-> W gamma plus X cross section at root s=1.96 TeV and WW gamma anomalous coupling limits

The WWγ triple gauge boson coupling parameters are studied using pp̄rarr; νγ+X(=e,μ) events at s=1.96 TeV. The data were collected with the D0 detector from an integrated luminosity of 162pb-1 delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for pp̄→W(γ)+X→ νγ+X with ETγ>8 GeV and ΔR γ> 0.7 is 14.8±1.6(stat)±1.0(syst) ±1.0(lum)pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88<Δκγ<0.96 and -0. 20<λγ<0.20. © 2005 The American Physical Society.

Measurement of the tt̄ production cross section in pp̄ collisions at √s = 1.96 TeV in dilepton final states

We present a measurement of the top quark pair (tt̄) production cross section in pp̄ collisions at √s=1.96 TeV using events with two charged leptons in the final state. This analysis utilizes an integrated luminosity of 224-243 pb-1 collected with the DØ detector at the Fermilab Tevatron Collider. We observe 13 events in the e+e -, eμ and μ+μ- channels with an expected background of 3.2±0.7 events. For a top quark mass of 175 GeV, we measure a tt̄ production cross section of σtt̄=8. 6-2.7 +3.2(stat)±1.1(syst)±0.6(lumi) pb, consistent with the standard model prediction. © 2005 Elsevier B.V. All rights reserved.

Search for squarks and gluinos in events with jets and missing transverse energy in p(p)over-bar collisions at root s-=1.96 TeV

The results of a search for squarks and gluinos using data from p over(p, ̄) collisions recorded at a center-of-mass energy of 1.96 TeV by the DØ detector at the Fermilab Tevatron Collider are reported. The topologies analyzed consist of acoplanar-jet and multijet events with large missing transverse energy. No evidence for the production of squarks or gluinos was found in a data sample of 310 pb-1. Lower limits of 325 and 241 GeV were derived at the 95% C.L. on the squark and gluino masses, respectively, within the framework of minimal supergravity with tan β = 3, A0 = 0, and μ < 0. © 2006 Elsevier B.V. All rights reserved.

Z gamma production and limits on anomalous ZZ gamma and Z gamma gamma couplings in pp collisions at root s=1.96 TeV

We present a study of eeγ and μμγ events using 1109 (1009) pb-1 of data in the electron (muon) channel, respectively. These data were collected with the DØ detector at the Fermilab Tevatron p over(p, ̄) collider at sqrt(s) = 1.96   TeV. Having observed 453 (515) candidates in the eeγ (μμγ) final state, we measure the Zγ production cross section for a photon with transverse energy ET > 7   GeV, separation between the photon and leptons Δ Rℓ γ > 0.7, and invariant mass of the di-lepton pair Mℓ ℓ > 30   GeV / c2, to be 4.96 ± 0.30 (stat . + syst .) ± 0.30 (lumi .)   pb, in agreement with the Standard Model prediction of 4.74 ± 0.22   pb. This is the most precise Zγ cross section measurement at a hadron collider. We set limits on anomalous trilinear Zγγ and ZZγ gauge boson couplings of - 0.085 < h30 γ < 0.084, - 0.0053 < h40 γ < 0.0054 and - 0.083 < h30 Z < 0.082, - 0.0053 < h40 Z < 0.0054 at the 95% C.L. for the form-factor scale Λ = 1.2   TeV.

Search for Randall-Sundrum gravitons with 1 fb(-1) of data from p(p)over-bar collisions at root s=1.96 TeV

We search for decays of Kaluza-Klein excitations of the graviton in the Randall-Sundrum model of extra dimensions to e+e- and in 1 fb-1 of pp collisions at s=1.96 TeV collected by the D0 detector at the Fermilab Tevatron. We set 95% confidence level upper limits on the production cross section times branching fraction, which translate into lower limits on the mass of the lightest excitation between 300 and 900 GeV for values of the coupling k/M Pl between 0.01 and 0.1. © 2008 The American Physical Society.

Search for scalar neutrino superpartners in e+mu final states in p(p)over-bar collisions at root s=1.96 TeV

We report a search for R-parity-violating production and decay of sneutrino particles in the eμ final state with 1.04±0.06fb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2006. Good agreement between the data and the standard model prediction is observed. With no evidence for new physics, we set limits on the R-parity-violating couplings λ311′ and λ312 as a function of the sneutrino mass. © 2008 The American Physical Society.

First study of the radiation-amplitude zero in W gamma production and limits on anomalous WW gamma couplings at root s=1.96 TeV

We present results from a study of pp̄→Wγ+X events utilizing data corresponding to 0.7fb-1 of integrated luminosity at s=1.96TeV collected by the D0 detector at the Fermilab Tevatron Collider. We set limits on anomalous WWγ couplings at the 95% C.L. The one-dimensional 95% C.L. limits are 0.49<κγ<1.51 and -0.12<λγ<0.13. We make the first study of the charge-signed rapidity difference between the lepton and the photon and find it to be indicative of the standard model radiation-amplitude zero in the Wγ system. © 2008 The American Physical Society.

Observation of a narrow mass state decaying into Υ(1S)+γ in pp̄ collisions at s=1.96 TeV

Using data corresponding to an integrated luminosity of 1.3fb -1, we observe a narrow mass state decaying into Υ(1S)+γ, where the Υ(1S) meson is detected by its decay into a pair of oppositely charged muons, and the photon is identified through its conversion into an electron-positron pair. The significance of this observation is 5.6 standard deviations. The mass of the state is centered at 10.551±0.014(stat) ±0.017(syst)GeV/c2, which is consistent with that of the state recently observed by the ATLAS Collaboration. © 2012 American Physical Society.

Measurement of angular correlations of jets at s=1.96 TeV and determination of the strong coupling at high momentum transfers

We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance δR in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of δR and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb -1 collected with the D0 detector at the Fermilab Tevatron Collider in pp- collisions at s=1.96 TeV. The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50-400 GeV. © 2012 Elsevier B.V.