Measurement of energy flow at large pseudorapidities in pp collisions at root s=0.9 and 7 TeV

The energy flow, dE/d eta, is studied at large pseudorapidities in proton-proton collisions at the LHC, for centre-of-mass energies of 0.9 and 7 TeV. The measurements are made using the CMS detector in the pseudorapidity range 3:15 < vertical bar eta vertical bar < 4.9, for both minimum-bias events and events with at least two high-momentum jets. The data are compared to various pp Monte Carlo event generators whose theoretical models and input parameter values are sensitive to the energy-flow measurements. Inclusion of multiple-parton interactions in the Monte Carlo event generators is found to improve the description of the energy-flow measurements.

A nonisothermal study of the kinetics of the nanoporosity elimination in sonogels-derived silica xerogels

A nonisothermal study of the kinetics of the nanoporosity elimination in monolithic silica xerogels, prepared from acid and ultrasound catalyzed hydrolysis of tetraethylortosilicate (TEOS), has been carried out by means of in situ linear shrinkage measurements performed with different heating rates. The study could be applied up to almost alpha similar to 0.6 of the volume fraction alpha of eliminated pores. The activation energy was found increasing from about 3.2 x 10(2) kJ/mol for alpha similar to 0.06 up to about 4.4 x 10(2) kJ/mol for alpha. similar to 0.44. The sintering process accompanying the nanopore elimination in this set of xerogels is in agreement with a viscous flux sintering process with the hydroxyl content diminishing with the volume fraction of eliminated pores. All the volume fraction of eliminated pores versus temperature (T) curves can be matched onto a unique curve with an appropriate rescaling of the T axis, independent of the heating rate. This scaling property suggests that the path of sintering seems the same, regardless of the heating rate; the difference is that the rate is faster at higher temperature.

Removal of epulis fissuratum associated to vestibuloplasty with carbon dioxide laser

There have been numerous surgical techniques developed for removing the epulis fissuratum lesions in order to improve alveolar ridge contour and improving adaptation of full prostheses. Most of these techniques can cause postoperative complications, such as oedema, pain, difficulty in swallowing and jaw movements, haemorrhage, infections and slow placement of final prostheses. The use of carbon dioxide (CO2) laser for the surgical removal of epulis lesions has resulted in many significant improvements including convenient mucosa removal, no bleeding or need for sutures, and minimal postoperative pain and oedema. This study is of 15 cases of removal of extensive epulis with vestibuloplasty in the maxilla and mandible that was carried out with CO2 laser, with no postoperative complications, rapid healing, and excellent aesthetic and functional outcome, all of which allowed for more rapid placement of final prosthesis.

Role of oxygen vacancies in the magnetic and dielectric properties of the high-dielectric-constant system CaCu3Ti4O12: An electron-spin resonance study

We report experiments of electron spin resonance (ESR) of Cu2+ in polycrystalline samples of CaCu3Ti4O12 post-annealed in different atmospheres. After being synthesized by solid state reaction, pellets of CaCu3Ti4O12 were annealed for 24 h at 1000 degrees C under air, Ar or O-2. Our temperature dependent ESR data revealed for all samples nearly temperature independent g value (2.15(1)) and linewidth for T > T-N approximate to 25 K. However, the values of ESR linewidth are strongly affected by the oxygen content in the sample. For instance, argon post-annealed samples show a much larger linewidth than the O-2 or air post-annealed samples. We attribute this broadening to an increase of the dipolar homogeneous broadening of the Cu2+ ESR lines due to the presence of oxygen vacancies which induce an S=1/2 spin inside the TiO6 octahedra. Correlation between a systematic dependence of the ESR linewidth on the oxygen content and the high dielectric constant of these materials is addressed. Also, ESR, magnetic susceptibility, and specific heat data for a single crystal of CaCu3Ti4O12 and for polycrystals of CdCu3Ti4O12 are reported.

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 charge ratio of atmospheric muons with the CMS detector

We present a measurement of the ratio of positive to negative muon fluxes from cosmic ray interactions in the atmosphere, using data collected by the CMS detector both at ground level and in the underground experimental cavern at the CERN LHC. Muons were detected in the momentum range from 5 GeV/. c to 1 TeV/. c. The surface flux ratio is measured to be 1.2766±0.0032(stat.)±0.0032(syst.), independent of the muon momentum, below 100 GeV/. c. This is the most precise measurement to date. At higher momenta the data are consistent with an increase of the charge ratio, in agreement with cosmic ray shower models and compatible with previous measurements by deep-underground experiments. © 2010.

First measurement of the underlying event activity at the LHC with √ = 0.9 TeV

A measurement of the underlying activity in scattering processes with pT scale in the GeV region is performed in proton-proton collisions at √ = 0.9 TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged particles with pseudorapidity {pipe}η{pipe} < 2, pT > 0.5 GeV/c, and azimuthal direction transverse to that of the leading object. © 2010 CERN for benefit of the CMS collaboration.

Prompt and non-prompt J/ψ production in pp collisions at √s =7 TeV

The production of J/ψ mesons is studied in pp collisions at √s = 7 TeV with the CMS experiment at the LHC. The measurement is based on a dimuon sample corresponding to an integrated luminosity of 314 nb-1. The J/ψ differential cross section is determined, as a function of the J/ψ transverse momentum, in three rapidity ranges. A fit to the decay length distribution is used to separate the prompt from the non-prompt (b hadron to J/ψ) component. Integrated over J/ψ transverse momentum from 6.5 to 30 GeV/c and over rapidity in the range {pipe}y{pipe} < 2.4, the measured cross sections, times the dimuon decay branching fraction, are 70.9 ± 2.1(stat.) ± 3.0(syst.) ± 7.8(luminosity) nb for prompt J/ψ mesons assuming unpolarized production and 26.0 ± 1.4(stat.) ± 1.6(syst.) ± 2.9(luminosity) nb for J/ψ mesons from b-hadron decays. © CERN for the benefit of the CMS collaboration 2011.

Measurement of the Drell-Yan cross section in pp collisions at √ s = 7 TeV

The Drell-Yan differential cross section is measured in pp collisions at √ s = 7TeV, from a data sample collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 36 pb-1. The cross section measurement, normalized to the measured cross section in the Z region, is reported for both the dimuon and dielectron channels in the dilepton invariant mass range 15{600 GeV. The normalized cross section values are quoted both in the full phase space and within the detector acceptance. The effect of final state radiation is also identified. The results are found to agree with theoretical predictions. Copyright CERN.

Charged particle transverse momentum spectra in pp collisions at √s = 0:9 and 7 TeV

The charged particle transverse momentum (pT) spectra are presented for pp collisions at √s = 0:9 and 7TeV. The data samples were collected with the CMS detector at the LHC and correspond to integrated luminosities of 231 μb-1 and 2.96 pb-1, respectively. Calorimeter-based high-transverse-energy triggers are employed to enhance the statistical reach of the high-pT measurements. The results are compared with leading and next-toleading order QCD and with an empirical scaling of measurements at different collision energies using the scaling variable xT - 2pT=ps over the pT range up to 136 GeV/c. Using a combination of xT scaling and direct interpolation at fixed pT, a reference transverse momentum spectrum at √s = 2:76TeV is constructed, which can be used for studying high-pT particle suppression in the dense QCD medium produced in heavy-ion collisions at that centre-of-mass energy. Copyright CERN.

Search for supersymmetry in pp collisions at √s = 7 TeV in events with a single lepton, jets, and missing transverse momentum

Results are reported from a search for physics beyond the standard model in proton-proton collisions at a center-of-mass energy of 7TeV, focusing on the signature with a single, isolated, high-transverse-momentum lepton (electron or muon), energetic jets, and large missing transverse momentum. The data sample comprises an integrated luminosity of 36 pb-1, recorded by the CMS experiment at the LHC. The search is motivated by models of new physics, including supersymmetry. The observed event yields are consistent with standard model backgrounds predicted using control samples obtained from the data. The characteristics of the event sample are consistent with those expected for the production of tt̄ and W+jets events. The results are interpreted in terms of limits on the parameter space for the constrained minimal supersymmetric extension of the standard model.

Measurement of the underlying event activity at the LHC with √s = 7 TeV and comparison with √s = 0:9 TeV

A measurement of the underlying activity in events with a jet of transverse momentum in the several GeV region is performed in proton-proton collisions at √ s = 0:9 and 7TeV, using data collected by the CMS experiment at the LHC. The production of charged particles with pseudorapidity |η|<2 and transverse momentum pT >0:5 GeV/c is studied in the azimuthal region transverse to that of the leading set of charged particles forming a track-jet. A significant growth of the average multiplicity and scalar-pT sum of the particles in the transverse region is observed with increasing pT of the leading trackjet, followed by a much slower rise above a few GeV/c. For track-jet pT larger than a few GeV/c, the activity in the transverse region is approximately doubled with a centreof- mass energy increase from 0:9 to 7TeV. Predictions of several QCD-inspired models as implemented in pythia are compared to the data.

Influência do consumo do café (com e sem cafeína) ou da cafeína isolada sobre a fibrose e a promoção da hepatocarcinogênese química em ratos Wistar machos

Pós-graduação em Patologia - FMB

Testes of Astyanax altiparanae: The Sertoli cell functions in a semicystic spermatogenesis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)