6,393 research outputs found
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
To the centenary of the birth of outstanding evolutionist Dmitri Konstantinovich Belyaev
No full textThis paper is a tribute to outstanding evolutionary biologist Dmitri Konstantinovich Belyaev in connection with the forthcoming centenary of his birth. His work on variation-related mechanisms in animal domestication made this process much faster. Belyaev is at length described as a person, as a scientist and as the organizer of the Institute of Cytology and Genetics of the Siberian Branch of the USSR Academy of Sciences. The author had for many years worked as Belyaev’s Deputy for Science, and, when Dmitri Konstantinovich passed away, had for 22 years headed the Institute of Cytology and Genetics. Belyaev’s life was not easy: he was a priest’s son and an “enemy of the people”’s brother. He was in the battlefield all through the Great Patriotic War and became a man of steel. His struggle for the restoration of genetics in the country, his commitment to setting up and maintaining relationships between masters and followers and many more other aspects of his life are considered. The global importance of the “master – follower” paradigm as a basis of the continuity of generations is underlined and re-underlined, for this is a very special point in the scientific community, especially when new schools of science emerge
Measurement of J/ψ polarization in pp collisions at √s=7 TeV
No full textAn angular analysis of the decay J/ψ→μ+μ− is performed to measure the polarization of prompt J/ψ mesons produced in pp collisions at √s=7TeV. The dataset corresponds to an integrated luminosity of 0.37 fb−1 collected with the LHCb detector. The measurement is presented as a function of transverse momentum, pT, and rapidity, y, of the J/ψ meson, in the kinematic region 2<pT<15GeV/c and 2.0<y<4.5
Observation of J/ψ-pair production in pp collisions at √s=7 TeV
No full textThe production of J/ψ pairs in proton–proton collisions at a centre-of-mass energy of 7 TeV has been observed using an integrated luminosity of 37.5 pb−1 collected with the LHCb detector. The production cross-section for pairs with both J/ψ in the rapidity range 2 < yJ/ψ < 4.5 and transverse momentum pJ/ψ T <10 GeV/c is σJ/ψJ/ψ =5.1±1.0±1.1 nb, where the first uncertainty is statistical and the second systematic
Double-stranded nucleic acids in liquid-crystalline dispersions as building blocks for cross-linked supramolecular structures
No full textMeasurement of the effective B0s→K+K− lifetime
No full textA measurement of the effective lifetime is presented using approximately 37 pb−1 of data collected by LHCb during 2010. This quantity can be used to put constraints on contributions from processes beyond the Standard Model in the meson system and is determined by two complementary approaches as
τKK=1.440±0.096 (stat)±0.008 (syst)±0.003 (model) ps
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
No full textAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
Measurements of the branching fractions of B+→ppK+ decays
No full textThe branching fractions of the decay B+ → pp̄K+ for different intermediate states are measured using data, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment. The total branching fraction, its charmless component Mpp̄ < 2.85 GeV/c2 and the branching fractions via the resonant cc̄ states η c(1S) and ψ(2S) relative to the decay via a J/ψ intermediate state are [Equation not available: see fulltext.] Upper limits on the B + branching fractions into the η c(2S) meson and into the charmonium-like states X(3872) and X(3915) are also obtained
Measurement of b-hadron branching fractions for two-body decays into charmless charged hadrons
No full textBased on data corresponding to an integrated luminosity of 0.37 fb−1 collected by the LHCb experiment in 2011, the following ratios of branching fractions are measured: B(B0→π+π−)/B(B0→K+π−)=0.262±0.009±0.017,(fs/fd)⋅B(B0s→K+K−)/B(B0→K+π−)=0.316±0.009±0.019,(fs/fd)⋅B(B0s→π+K−)/B(B0→K+π−)=0.074±0.006±0.006,(fd/fs)⋅B(B0→K+K−)/B(B0s→K+K−)=0.018+0.008−0.007±0.009,(fs/fd)⋅B(B0s→π+π−)/B(B0→π+π−)=0.050+0.011−0.009±0.004,B(Λ0b→pπ−)/B(Λ0b→pK−)=0.86±0.08±0.05, where the first uncertainties are statistical and the second systematic. Using the current world average of B(B0→K+π−) and the ratio of the strange to light neutral B meson production f s /f d measured by LHCb, we obtain: B(B0→π+π−)=(5.08±0.17±0.37)×10−6,B(B0s→K+K−)=(23.0±0.7±2.3)×10−6,B(B0s→π+K−)=(5.4±0.4±0.6)×10−6,B(B0→K+K−)=(0.11+0.05−0.04±0.06)×10−6,B(B0s→π+π−)=(0.95+0.21−0.17±0.13)×10−6.
The measurements of B(B0s→K+K−) , B(B0s→π+K−) and B(B0→K+K−) are the most precise to date. The decay mode B0s→π+π− is observed for the first time with a significance of more than 5σ
Approach to Analysis of Self-Selected Interval Data
No full textWe analyze an approach to quantitative information elicitation in surveys that includes many currently popular variants as special cases. Rather than asking the individual to state a point estimate or select between given brackets, the individual can self-select any interval of choice. We propose a new estimator for such interval censored data. It can be viewed as an extension of Turnbull's estimator (Turnbull(1976)) for interval censored data. A detailed empirical example is provided, using a survey on the valuation of a public good. We estimate survival functions based on a Weibull and a mixed Weibull/exponential distribution and prove that a consistent maximum likelihood estimator exists and that its accuracy can be consistently estimated by re-sampling methods in these two families of distributions.Interval data; Maximum Likelihood; Turnbull estimator; willingness-to-pay; quantitative elicitation
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