20 research outputs found

    High-resolution abundance analysis of four red giants in the globular cluster NGC 6558

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    Context. NGC 6558 is a bulge globular cluster with a blue horizontal branch (BHB), combined with a metallicity of [Fe/H] ≈ −1.0. It is similar to HP 1 and NGC 6522, which could be among the oldest objects in the Galaxy. Element abundances in these clusters could reveal the nature of the first supernovae. Aims. We aim to carry out detailed spectroscopic analysis for four red giants of NGC 6558, in order to derive the abundances of the light elements C, N, O, Na, Al, the α-elements Mg, Si, Ca, Ti, and the heavy elements Y, Ba, and Eu. Methods. High-resolution spectra of four stars with FLAMES-UVES at VLT UT2-Kueyen were analysed. Spectroscopic parameter-derivation was based on excitation and ionization equilibrium of Fe I and Fe II. Results. This analysis results in a metallicity of [Fe/H] = − 1.17 ± 0.10 for NGC 6558. We find the expected α-element enhancements in O and Mg with [O/Fe] = +0.40, [Mg/Fe] = +0.33, and low enhancements in Si and Ca. Ti has a moderate enhancement of [Ti/Fe] = +0.22. The r-element Eu appears very enhanced with a mean value of [Eu/Fe] = +0.63. The first peak s-elements Y and Sr are also enhanced, these results have however to be treated with caution, given the uncertainties in the continuum definition; the use of neutral species (Sr I, Y I), instead of the dominant ionized species is another source of uncertainty. Ba appears to have a solar abundance ratio relative to Fe. Conclusions. NGC 6558 shows an abundance pattern that could be typical of the oldest inner bulge globular clusters, together with the pattern in the similar clusters NGC 6522 and HP 1. They show low abundances of the odd-Z elements Na and Al, and of the explosive nucleosynthesis α-elements Si, Ca, and Ti. The hydrostatic burning α-elements O and Mg are normally enhanced as expected in old stars enriched with yields from core-collapse supernovae, and the iron-peak elements Mn, Cu, Zn show low abundances, which is expected for Mn and Cu, but not for Zn. Finally, the cluster trio NGC 6558, NGC 6522, and HP 1 have relatively high abundances of first-peak heavy elements, variable second-peak element Ba, and the r-element Eu is enhanced. The latter is particularly high in NGC 6558

    UVES analysis of red giants in the bulge globular cluster NGC 6522

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    Context. NGC 6522 is a moderately metal-poor bulge globular cluster ([Fe/H] ~ −1.0), and it is a well-studied representative among a number of moderately metal-poor blue horizontal branch clusters located in the bulge. The NGC 6522 abundance pattern can give hints on the earliest chemical enrichment in the central Galaxy. Aims. The aim of this study is to derive abundances of the light elements C and N; alpha elements O, Mg, Si, Ca, and Ti; odd-Z elements Na and Al; neutron-capture elements Y, Zr, Ba, La, and Nd; and the r-process element Eu. We verify if there are first- and second-generation stars: we find clear evidence of Na–Al, Na–N, and Mg–Al correlations, while we cannot identify the Na–O anti-correlation from our data. Methods. High-resolution spectra of six red giants in the bulge globular cluster NGC 6522 were obtained at the 8m VLT UT2-Kueyen telescope with both the UVES and GIRAFFE spectrographs in FLAMES+UVES configuration. In light of Gaia data, it turned out that two of them are non-members, but these were also analysed. Spectroscopic parameters were derived through the excitation and ionisation equilibrium of Fe I and Fe II lines from UVES spectra. The abundances were obtained with spectrum synthesis. Comparisons of abundances derived from UVES and GIRAFFE spectra were carried out. Results. The present analysis combined with previous UVES results gives a mean radial velocity of vrhel = −15.62±7.7 km s−1 and a metallicity of [Fe/H] = −1.05 ± 0.20 for NGC 6522. Mean abundances of alpha elements for the present four member stars are enhanced with [O/Fe] = +0.38, [Mg/Fe] = ≈+0.28, [Si/Fe] ≈ +0.19, and [Ca/Fe] ≈ +0.13, together with the iron-peak element [Ti/Fe] ≈ +0.13, and the r-process element [Eu/Fe] = +0.40. The neutron-capture elements Y, Zr, Ba, and La show enhancements in the +0.08 < [Y/Fe] < +0.90, 0.11 < [Zr/Fe] < +0.50, 0.00 < [Ba/Fe] < +0.63, 0.00 < [La/Fe] < +0.45, and −0.10 < [Nd/Fe] < +0.70 ranges. We also discuss the spread in heavy-element abundances

    Measurement of the Forward-Backward Asymmetry in the B -> K(*) mu+ mu- Decay and First Observation of the Bs -> phi mu+ mu- Decay

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    We reconstruct the rare decays B+K+μ+μB^+ \to K^+\mu^+\mu^-, B0K(892)0μ+μB^0 \to K^{*}(892)^0\mu^+\mu^-, and Bs0ϕ(1020)μ+μB^0_s \to \phi(1020)\mu^+\mu^- in a data sample corresponding to 4.4fb14.4 {\rm fb^{-1}} collected in ppˉp\bar{p} collisions at s=1.96TeV\sqrt{s}=1.96 {\rm TeV} by the CDF II detector at the Fermilab Tevatron Collider. Using 121±16121 \pm 16 B+K+μ+μB^+ \to K^+\mu^+\mu^- and 101±12101 \pm 12 B0K0μ+μB^0 \to K^{*0}\mu^+\mu^- decays we report the branching ratios. In addition, we report the measurement of the differential branching ratio and the muon forward-backward asymmetry in the B+B^+ and B0B^0 decay modes, and the K0K^{*0} longitudinal polarization in the B0B^0 decay mode with respect to the squared dimuon mass. These are consistent with the theoretical prediction from the standard model, and most recent determinations from other experiments and of comparable accuracy. We also report the first observation of the Bs0ϕμ+μdecayandmeasureitsbranchingratioB^0_s \to \phi\mu^+\mu^- decay and measure its branching ratio {\mathcal{B}}(B^0_s \to \phi\mu^+\mu^-) = [1.44 \pm 0.33 \pm 0.46] \times 10^{-6}using using 27 \pm 6signalevents.Thisiscurrentlythemostrare signal events. This is currently the most rare B^0_s$ decay observed.Comment: 7 pages, 2 figures, 3 tables. Submitted to Phys. Rev. Let

    Measurements of the properties of Lambda_c(2595), Lambda_c(2625), Sigma_c(2455), and Sigma_c(2520) baryons

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    We report measurements of the resonance properties of Lambda_c(2595)+ and Lambda_c(2625)+ baryons in their decays to Lambda_c+ pi+ pi- as well as Sigma_c(2455)++,0 and Sigma_c(2520)++,0 baryons in their decays to Lambda_c+ pi+/- final states. These measurements are performed using data corresponding to 5.2/fb of integrated luminosity from ppbar collisions at sqrt(s) = 1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. Exploiting the largest available charmed baryon sample, we measure masses and decay widths with uncertainties comparable to the world averages for Sigma_c states, and significantly smaller uncertainties than the world averages for excited Lambda_c+ states.Comment: added one reference and one table, changed order of figures, 17 pages, 15 figure

    Search for a New Heavy Gauge Boson Wprime with Electron + missing ET Event Signature in ppbar collisions at sqrt(s)=1.96 TeV

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    We present a search for a new heavy charged vector boson WW^\prime decaying to an electron-neutrino pair in ppˉp\bar{p} collisions at a center-of-mass energy of 1.96\unit{TeV}. The data were collected with the CDF II detector and correspond to an integrated luminosity of 5.3\unit{fb}^{-1}. No significant excess above the standard model expectation is observed and we set upper limits on σB(Weν)\sigma\cdot{\cal B}(W^\prime\to e\nu). Assuming standard model couplings to fermions and the neutrino from the WW^\prime boson decay to be light, we exclude a WW^\prime boson with mass less than 1.12\unit{TeV/}c^2 at the 95\unit{%} confidence level.Comment: 7 pages, 2 figures Submitted to PR

    Search for heavy bottom-like quarks decaying to an electron or muon and jets in ppˉp\bar{p} collisions at s=1.96\sqrt{s}=1.96 TeV

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    We report the most sensitive direct search for pair production of fourth-generation bottom-like chiral quarks (bb') each decaying promptly to tWtW. We search for an excess of events with an electron or muon, at least five jets (one indentified as due to a bb or cc quark) and an imbalance of transverse momentum using data from ppˉp\bar{p} collisions collected by the CDF II detector at Fermilab with an integrated luminosity of 4.8 fb1^{-1}. We observe events consistent with background expectation and calculate upper limits on the bb' pair production cross section (σbbˉ30\sigma_{b\bar{b'}}\lesssim 30 fb for mb>m_{b'}>375 GeV/c2c^2) and exclude mb<372m_{b'}<372 \gevcc at 95% confidence level.Comment: For submission to PR

    First Measurement of the Angular Coefficients of Drell-Yan e(+)e(-) Pairs in the Z Mass Region from p(p)over-bar Collisions at root s=1.96 TeV

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    We report on the first measurement of the angular distributions of final state electrons in p (p) over bar -> gamma*/Z -> e(+)e(-) + X events produced in the Z boson mass region at root s = 1.96 TeV. The data sample collected by the CDF II detector for this result corresponds to 2.1 fb(-1) of integrated luminosity. The angular distributions are studied as a function of the transverse momentum of the electron-positron pair and show good agreement with the Lam-Tung relation, consistent with a spin-1 description of the gluon, and demonstrate that, at high values of the transverse momentum, Z bosons are produced via quark-antiquark annihilation and quark-gluon Compton processes

    Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from p(p)over-bar Collisions at root s=1.96 TeV

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    We present the results of a search for a very light CP-odd Higgs boson a(1)(0) originating from top quark decays t -> H(+/-)b -> W-+/-(*) a(1)(0)b, and subsequently decaying into tau(+)tau(-). Using a data sample corresponding to an integrated luminosity of 2.7 fb(-1) collected by the CDF II detector in p (p) over bar collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t -> H(+/-)b for various masses of H-+/- and a(1)(0)

    First Search for Multijet Resonances in root s=1.96 TeV p(p)over-bar Collisions

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    We present the first model independent search for three-jet hadronic resonances within multijet events in root s = 1.96 TeV p (p) over bar collisions at the Fermilab Tevatron using the CDF II detector. Pair production of supersymmetric gluinos and squarks with hadronic R-parity violating decays is employed as an example of a new physics benchmark for this signature. Selection criteria based on the kinematic properties of an ensemble of jet combinations within each event help to extract signal from copious QCD background. No significant excess outside the top quark mass window is observed in data with an integrated luminosity of 3.2 fb(-1). We place 95% confidence level limits on the production cross section sigma(p (p) over bar -> XX') X BR((g) over tilde(g) over tilde -> 3 jet + 3 jet) where X, X' = (g) over tilde, (q) over tilde, or (sic), with (q) over tilde, (sic) -> (g) over tilde + jet, as a function of gluino mass, in the range of 77 GeV/c(2) to 240 GeV/c(2)

    Comparison and optimization of genetic tools used for the identification of ancient fish remains recovered from archaeological excavations and museum collections in the Mediterranean region

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    Among the many fish species commercially exploited since prehistoric times, Atlantic bluefin tuna (Thunnus thynnus) is one of the most economically significant, having left an indelible imprint on several civilizations including the Phoenicians, Greeks, and Romans. Here, we describe our efforts to identify tuna specimens among the remains of 345 fish vertebrae and bones in several large collections from the Atlantic Ocean, Mediterranean Sea, and Black Sea, dating from the Late Iron Age (2nd century BCE) to the early 20th century (1911\u20131927). Unfortunately, ancient fish specimens are often mislabelled, which can cause a great deal of confusion among zoologists. Protocols were developed and optimized to overcome the unique challenges related to the compromised integrity of genetic material preserved in ancient bones. Three DNA isolation protocols were compared to maximize yields, and as reported for other faunal remains, a silica spin column-based method was proven most effective. Endogenous DNA was successfully extracted from the majority of bones and amplified using polymerase chain reactions (PCRs) and an assortment of four primer pairs targeting nuclear (internal transcribed spacer) and mitochondrial sequences (cytochrome oxidase subunit 1 and control region). Protocols targeting mitochondrial markers were more successful than those focused on nuclear targets. Due to the restricted length of the extracted DNA molecules, character-based keys containing diagnostic nucleotide substitutions were defined and used to identify 231 samples to genera, of which 171 were identified to species level. The success rate of assignment of specimens to species level varied between location and collection, reflecting variation in DNA preservation between different sites and environments. The methods detailed herein can be used to identify other ancient fish specimens and provide information about historical human diets, trade, species distribution, and biodiversity. The same tools can be applied to the analysis of processed food items with highly damaged DNA
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