Improved search for a Higgs boson produced in association with Z → l+ l- in pp collisions sqrt[s] = 1.96 TeV

We search for the standard model Higgs boson produced with a Z boson in 4.1 fb(-1) of integrated luminosity collected with the CDF II detector at the Tevatron. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electrons or muons, we set 95% credibility level upper limits on the ZH production cross section multiplied by the H → bb branching ratio. Improved analysis methods enhance signal sensitivity by 20% relative to previous searches. At a Higgs boson mass of 115 GeV/c2 we set a limit of 5.9 times the standard model cross section.     

Top quark mass measurement in the lepton + jets channel using a matrix element method and in situ jet energy calibration

A precision measurement of the top quark mass m(t) is obtained using a sample of tt events from pp collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m(t) and a parameter Δ(JES) used to calibrate the jet energy scale in situ. Using a total of 1087 events in 5.6 fb(-1) of integrated luminosity, a value of m(t)=173.0 ± 1.2 GeV/c(2) is measured.     

N = 14 shell closure in 22O viewed through a neutron sensitive probe

To investigate the behavior of the N = 14 neutron gap far from stability with a neutron-sensitive probe, proton elastic and 2(1)+ inelastic scattering angular distributions for the neutron-rich nucleus 22O were measured using the MUr à STrip detector array at the Grand Accélérateur National d'Ions Lourds facility. A deformation parameter beta(p,p') = 0.26 +/- 0.04 is obtained for the 2(1)+ state, much lower than in 20O, showing a weak neutron contribution to this state. A microscopic analysis was performed using matter and transition densities generated by continuum Skyrme-Hartree-Fock-Bogoliubov and quasiparticle random phase approximation calculations, respectively. The ratio of neutron to proton contributions to the 2(1)+ state is found close to the N/Z ratio, demonstrating a strong N = 14 shell closure in the vicinity of the neutron drip line.     

First flavor-tagged determination of bounds on mixing-induced CP violation in Bs0 --> J/psiphi decays

This Letter describes the first determination of bounds on the CP-violation parameter 2beta(s) using B(s)(0) decays in which the flavor of the bottom meson at production is identified. The result is based on approximately 2000 B(s)(0)-->J/psiphi decays reconstructed in a 1.35 fb(-1) data sample collected with the CDF II detector using pp collisions produced at the Fermilab Tevatron. We report confidence regions in the two-dimensional space of 2beta(s) and the decay-width difference DeltaGamma. Assuming the standard model predictions of 2beta(s) and DeltaGamma, the probability of a deviation as large as the level of the observed data is 15%, corresponding to 1.5 Gaussian standard deviations.     

Strong evidence for ZZ production in pp[over] collisions at sqrt[s]=1.96 TeV

We report the first evidence of Z boson pair production at a hadron collider with a significance exceeding 4 standard deviations. This result is based on a data sample corresponding to 1.9 fb(-1) of integrated luminosity from pp[over] collisions at sqrt[s]=1.96 TeV collected with the Collider Detector at Fermilab II detector. In the lll'l' channel, we observe three ZZ candidates with an expected background of 0.096(-0.063)+0.092 events. In the llnunu channel, we use a leading-order calculation of the relative ZZ and WW event probabilities to discriminate between signal and background. In the combination of lll'l' and llnunu channels, we observe an excess of events with a probability of 5.1 x 10(-6) to be due to the expected background. This corresponds to a significance of 4.4 standard deviations. The measured cross section is sigma(pp[over]-->ZZ)=1.4(-0.6)+0.7(stat+syst) pb, consistent with the standard model expectation.     

Virtual coupling potential for elastic scattering of Be on proton and carbon targets

The ^10,11Be(p, p) and (¹²C, ¹²C) reactions were analyzed to determine the influence of the weak binding energies of exotic nuclei on their interaction potential. The elastic cross sections were measured at GANIL in inverse kinematics using radioactive ^10,11Be beams produced at energies of 39.1A   and 38.4A MeV$38.4A\text{ MeV}$. The elastic proton scattering data were analyzed within the framework of the microscopic Jeukenne–Lejeune–Mahaux (JLM) nucleon–nucleus potential. The angular distributions are found to be best reproduced by reducing the real part of the microscopic optical potential, as a consequence of the coupling to the continuum. These effects modify deeply the elastic potential. Including the Virtual Coupling Potential (VCP), we show the ability of the general optical potentials to reproduce the data for scattering of unstable nuclei, using realistic densities. Finally, the concepts needed to develop a more general and microscopic approach of the VCP are discussed.     

Hard gamma as probe of nuclear dynamics

Experimental results concerning the ⁵⁸Ni + ⁵⁸Ni at 30 MeV/u and ⁵⁸Ni + ¹⁹⁷Au at 30 and 45 MeV/u reactions are presented. The emission mechanism of hard photons has been exploited to get information on the time evolution of the reactions. From the measured hard gamma multiplicity associated to different classes of heavy residues a quantitative estimate of the reaction centrality has been obtained. Moreover, evidence of a prompt Intermediate Mass Fragment (IMF) emission is shown for the Ni + Au reaction at 45 MeV/u for central collisions exploring the correlation function between thermal photons and IMF’s.     

Interaction of sodium and potassium ions withκ-carrageenan

Summary NMR and potentiometric methods revealed at least two types of interactions of Na⁺ and K⁺ ions with -carrageenan, viz., Coulombic interaction with polysaccharide sulfate groups, and a coordination one, leading, in the case of the Na⁺ ions, to formation of nonstoichiometric complexes. The absence of any correlation between the coordination binding density of the cations and their promoting effect on gelation process was demonstrated.