974 resultados para B - L symmetry
Resumo:
Sensory characteristics of Morada Nova lambs meat (muscles Biceps femoris, Longissimus and Triceps brachii) submitted to effects of ageing and injection of calcium chloride were studied. The lambs were slaughtered at 25 kg of body weight. After rigor mortis, muscles were removed and submitted to treatments. The variance analysis indicated that ageing and calcium chloride didn't influence the attributes flavor (6.71) and tenderness (7.13) of meats from Biceps femoris. The interaction among the factors wasn't significant for tenderness, however it was significant for flavor. Ageing didn't affect colour (7.08), flavor (7.42), tenderness (7.83) and global impression (7.58) of meats from Longissimus without calcium chloride, and meats with calcium chloride also didn't affect. Ageing and calcium chloride factor didn't influence the attributes flavor and tenderness of meats from Triceps brachii. The interaction among the factors wasn't significant for attributes flavor and tenderness. The sensory quality of Morada Nova lambs meat, was shown similar with relationship to evaluated attributes when it was submitted to ageing and injection with calcium chloride.
Resumo:
The purpose of this study was to evaluate the tissue composition and carcass muscularity of 32 legs of Ile de France lambs fed with diets containing sunflower seeds and vitamin E, with mean body weight of 15 kg, lodged in individual pens at 15 kg and slaughtered at 32 kg of body weight. The treatments influenced (P<0,05) leg weight, femur length and muscle: bone ratio, being the highest values (2,13 kg, 16,19 cm and 7,38, respectively) in lambs that received diet without sunflower seeds and vitamin E. The other variables were not affected (P>0,05) by the treatments. The interaction of the sunflower and vitamin E was positive for bone total weights and intramuscular fat.
Resumo:
We report the combination of recent measurements of the helicity of the W boson from top quark decay by the CDF and D0 collaborations, based on data samples corresponding to integrated luminosities of 2.7-5.4fb -1 of pp̄ collisions collected during Run II of the Fermilab Tevatron collider. Combining measurements that simultaneously determine the fractions of W bosons with longitudinal (f 0) and right-handed (f +) helicities, we find f 0=0.722±0.081[±0.062(stat)±0.052(syst)] and f +=-0.033±0.046[±0.034(stat)±0.031(syst)]. Combining measurements where one of the helicity fractions is fixed to the value expected in the standard model, we find f 0=0.682±0. 057[±0.035(stat)±0.046(syst)] for fixed f + and f +=-0.015±0.035[±0.018(stat)±0.030(syst)] for fixed f 0. The results are consistent with standard model expectations. © 2012 American Physical Society.
Resumo:
Results are presented on a search for a light charged Higgs boson that can be produced in the decay of the top quark t → H +b and which, in turn, decays into τ +ν t. The analysed data correspond to an integrated luminosity of about 2 fb -1 recorded in protonproton collisions at √s = 7 TeV by the CMS experiment at the LHC. The search is sensitive to the decays of the top quark pairs tt̄ → H ±W ∓bb̄ and tt̄ → H ±H ∓bb̄. Various final states have been studied separately, all requiring presence of a τ lepton from H + decays, missing transverse energy, and multiple jets. Upper limits on the branching fraction B(t → H +b) in the range of 2-4% are established for charged Higgs boson masses between 80 and 160 GeV, under the assumption that B(H + → τ +ν τ) = 1.
Resumo:
A search has been performed for long-lived particles that have stopped in the CMS detector, during 7TeV proton-proton operations of the CERN LHC. The existence of such particles could be inferred from observation of their decays when there were no protonproton collisions in the CMS detector, namely during gaps between LHC beam crossings. Using a data set in which CMS recorded an integrated luminosity of 4.0 fb -1, and a search interval corresponding to 246 hours of trigger live time, 12 events are observed, with a mean background prediction of 8:6 ± 2:4 events. Limits are presented at 95% confidence level on long-lived gluino and stop production, over 13 orders of magnitude of particle lifetime. Assuming the cloud model of R-hadron interactions, a gluino with mass below 640 GeV and a stop with mass below 340 GeV are excluded, for lifetimes between 10 μs and 1000 s.
Resumo:
The first measurement of the charged component of the underlying event using the novel jet-area/median approach is presented for proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data were recorded in 2010 with the CMS experiment at the LHC. A new observable, sensitive to soft particle production, is introduced and investigated inclusively and as a function of the event scale defined by the transverse momentum of the leading jet. Various phenomenological models are compared to data, with and without corrections for detector effects. None of the examined models describe the data satisfactorily. © 2012 SISSA.
Resumo:
Physical and chemical adsorption of CO 2 on ZnO surfaces were studied by means of two different implementations of periodic density functional theory. Adsorption energies were computed and compared to values in the literature. In particular, it was found that the calculated equilibrium structure and internuclear distances are in agreement with previous work. CO 2 adsorption was analyzed by inspection of the density of states and electron localization function. Valence bands, band gap and final states of adsorbed CO 2 were investigated and the effect of atomic displacements analyzed. The partial density of states (PDOS) of chemical adsorption of CO 2 on the ZnO(0001) surface show that the p orbitals of CO 2 were mixed with the ZnO valence band state appearing at the top of the valence band and in regions of low-energy conduction band. [Figure not available: see fulltext.] © 2012 Springer-Verlag Berlin Heidelberg.
Resumo:
The top quark is the heaviest known elementary particle, with a mass about 40 times larger than the mass of its isospin partner, the bottom quark. It decays almost 100% of the time to a W boson and a bottom quark. Using top-antitop pairs at the Tevatron proton-antiproton collider, the CDF and D0 Collaborations have measured the top quark's mass in different final states for integrated luminosities of up to 5.8fb -1. This paper reports on a combination of these measurements that results in a more precise value of the mass than any individual decay channel can provide. It describes the treatment of the systematic uncertainties and their correlations. The mass value determined is 173.18±0.56(stat)±0.75(syst)GeV or 173.18±0.94GeV, which has a precision of ±0.54%, making this the most precise determination of the top-quark mass. © 2012 American Physical Society.
Resumo:
Results are presented from a search for heavy bottom-like quarks, pair-produced in pp collisions at √s = 7TeV, undertaken with the CMS experiment at the LHC. The b′ quarks are assumed to decay exclusively to tW. The b′b̄′ → tW-t̄W+ process can be identified by its distinctive signatures of three leptons or two leptons of same charge, and at least one b-quark jet. Using a data sample corresponding to an integrated luminosity of 4.9 fb-1, observed events are compared to the standard model background predictions, and the existence of b′ quarks having masses below 611 GeV/c2 is excluded at 95% confidence level.
Resumo:
A model-independent search for the production of heavy resonances decaying into top-antitop quark pairs is presented. The search is based on events containing one lepton (muon or electron) and at least two jets selected from data samples corresponding to an integrated luminosity of 4.4-5.0 fb -1 collected in pp collisions at √s =7 TeV. Results are presented from the combination of two dedicated searches optimized for boosted production and production at threshold. No excess of events is observed over the expected yield from the standard model processes. Topcolor Z′ bosons with narrow (wide) width are excluded at 95% confidence level for masses below 1.49 (2.04) TeV and an upper limit of 0.3 (1.3) pb or lower is set on the production cross section times branching fraction for resonance masses above 1 TeV. Kaluza-Klein excitations of a gluon with masses below 1.82 TeV (at 95% confidence level) in the Randall-Sundrum model are also excluded, and an upper limit of 0.7 pb or lower is set on the production cross section times branching fraction for resonance masses above 1 TeV.[Figure not available: See fulltext.] © 2012 CERN for the benefit of the CMS collaboration.
Resumo:
A measurement of the single-top-quark t-channel production cross section in pp collisions at √s=7 TeV with the CMS detector at the LHC is presented. Two different and complementary approaches have been followed. The first approach exploits the distributions of the pseudorapidity of the recoil jet and reconstructed top-quark mass using background estimates determined from control samples in data. The second approach is based on multivariate analysis techniques that probe the compatibility of the candidate events with the signal. Data have been collected for the muon and electron final states, corresponding to integrated luminosities of 1.17 and 1.56 fb-1, respectively. The single-top-quark production cross section in the t-channel is measured to be 67.2±6.1 pb, in agreement with the approximate next-to-next-to-leading- order standard model prediction. Using the standard model electroweak couplings, the CKM matrix element |V tb| is measured to be 1.020 ± 0.046 (meas.) ± 0.017 (theor.). © 2012 CERN for the benefit of the CMS collaboration.
Resumo:
Results are presented from a search for third-generation leptoquarks and scalar bottom quarks in a sample of proton-proton collisions at √s=7Tev collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.7 fb-1. A scenario where the new particles are pair produced and each decays to a b quark plus a tau neutrino or neutralino is considered. The number of observed events is found to be in agreement with the standard model prediction. Upper limits are set at 95% confidence level on the production cross sections. Leptoquarks with masses below ~450 GeV are excluded. Upper limits in the mass plane of the scalar quark and neutralino are set such that scalar bottom quark masses up to 410 GeV are excluded for neutralino masses of 50 GeV. © 2012 CERN for the benefit of CMS collaboration.
Resumo:
The mass of the top quark is measured using a sample of t̄t candidate events with one electron or muon and at least four jets in the final state, collected by CMS in pp collisions at √s =7 TeV at the LHC. A total of 5174 candidate events is selected from data corresponding to an integrated luminosity of 5.0 fb-1. For each event the mass is reconstructed from a kinematic fit of the decay products to a t̄t hypothesis. The top-quark mass is determined simultaneously with the jet energy scale (JES), constrained by the known mass of the W boson in q̄q decays, to be 173.49 ± 0.43 (stat. + JES) ±0.98 (syst.) GeV. © 2012 CERN for the benefit of the CMS collaboration.
Resumo:
A search for a doubly-charged Higgs boson in pp collisions at √s=7 TeV is presented. The data correspond to an integrated luminosity of 4. 9 fb-1, collected by the CMS experiment at the LHC. The search is performed using events with three or more isolated charged leptons of any flavor, giving sensitivity to the decays of pair-produced triplet components Φ++Φ--, and Φ++Φ- from associated production. No excess is observed compared to the background prediction, and upper limits at the 95 % confidence level are set on the Φ++ production cross section, under specific assumptions on its branching fractions. Lower bounds on the Φ++ mass are reported, providing significantly more stringent constraints than previously published limits. © 2012 CERN for the benefit of the CMS collaboration.