124 research outputs found

    Digital Computer Modeling of Limestone Groundwater Systems

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    Because limestone groundwater flows mainly In discrete openings, limestone aquifers are fundamentally different from aquifers In granular rocks. A digital computer program which simulates flow in a limestone aquifer as a pipe network was written and compared with the Sinkhole Plain aquifer of west-central Kentucky. A reasonably good fit between observed parameters of the aquifer and those calculated were obtained under assumed conditions of both laminar and turbulent now In the aquifer. The Indicated gross permeablllty of the aquifer is 5600 melnzers with an assumed aquifer thickness of 100 feet. The location and discharge of springs along the streams bounding the aquifer are predicted. With further refinements to the computational routines, additional features of the aquifer can be modelled, and more refined predictions can be made of water budget parameters, location of flow paths, and development of the aquifer

    Study of J /ψ production in Jets

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    The production of J/ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13 TeV. The fraction of the jet transverse momentum carried by the J/ψ meson, z(J/ψ)≡pT(J/ψ)/pT(jet), is measured using jets with pT(jet)>20 GeV in the pseudorapidity range 2.5<η(jet)<4.0. The observed z(J/ψ)distribution for J/ψ mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the pT fraction carried by prompt J/ψ mesons in jets at any experiment

    Study of J=ψ Production in Jets

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    The production of J/ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13 TeV. The fraction of the jet transverse momentum carried by the J/ψ meson, z(J/ψ)≡p[subscript T](J/ψ)/p[subscript T](jet), is measured using jets with p[subscript T](jet) > 20  GeV in the pseudorapidity range 2.5<η(jet)<4.0. The observed z(J/ψ) distribution for J/ψ mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the p[subscript T] fraction carried by prompt J/ψ mesons in jets at any experiment.National Science Foundation (U.S.

    Measurement of the CP asymmetry in B- -&gt; (Ds-D0) and B- -&gt; (D-D0) decays

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    The CP asymmetry in B- -&gt; (Ds-D0) and B- -&gt; (D-D0) decays is measured using LHCb data corresponding to an integrated luminosity of 3.0 fb(-1), collected in pp collisions at centre-of-mass energies of 7 and 8TeV. The results are A(CP) (B- -&gt; (Ds-D0)) = (-0.4 +/- 0.5 +/- 0.5)% and A(CP) (B- -&gt; (D-D0)) = (2.3 +/- 2.7 +/- 0.4)%, where the first uncertainties are statistical and the second systematic. This is the first measurement of A(CP) (B- -&gt; (Ds-D0)) and the most precise determination of A(CP) (B- -&gt; (D-D0)). Neither result shows evidence of CP violation

    Search for the decays Bs0→τ+τ− and B0→τ+τ−

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    A search for the rare decays B0 s → Ï„ĂŸÏ„âˆ’ and B0 → Ï„ĂŸÏ„âˆ’ is performed using proton–proton collision data collected with the LHCb detector. The data sample corresponds to an integrated luminosity of 3 fb−1 collected in 2011 and 2012. The τ leptons are reconstructed through the decay τ− → Ï€âˆ’Ï€ĂŸÏ€âˆ’ÎœÏ„. Assuming no contribution from B0 → Ï„ĂŸÏ„âˆ’ decays, an upper limit is set on the branching fraction BĂ°B0 s → Ï„ĂŸÏ„âˆ’Ăž &lt; 6.8 × 10−3 at the 95% confidence level. If instead no contribution from B0 s → Ï„ĂŸÏ„âˆ’ decays is assumed, the limit is BĂ°B0 → Ï„ĂŸÏ„âˆ’Ăž &lt; 2.1 × 10−3 at the 95% confidence level. These results correspond to the first direct limit on BĂ°B0 s → Ï„ĂŸÏ„âˆ’Ăž and the world’s best limit on BĂ°B0 → Ï„ĂŸÏ„âˆ’Ăž

    Measurement of the B_{s}^{0}→Ό^{+}ÎŒ^{-} Branching Fraction and Effective Lifetime and Search for B^{0}→Ό^{+}ÎŒ^{-} Decays.

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    A search for the rare decays B_{s}^{0}→Ό^{+}ÎŒ^{-} and B^{0}→Ό^{+}ÎŒ^{-} is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4  fb^{-1}. An excess of B_{s}^{0}→Ό^{+}ÎŒ^{-} decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B_{s}^{0}→Ό^{+}ÎŒ^{-})=(3.0±0.6_{-0.2}^{+0.3})×10^{-9}, where the first uncertainty is statistical and the second systematic. The first measurement of the B_{s}^{0}→Ό^{+}ÎŒ^{-} effective lifetime, τ(B_{s}^{0}→Ό^{+}ÎŒ^{-})=2.04±0.44±0.05  ps, is reported. No significant excess of B^{0}→Ό^{+}ÎŒ^{-} decays is found, and a 95% confidence level upper limit, B(B^{0}→Ό^{+}ÎŒ^{-})<3.4×10^{-10}, is determined. All results are in agreement with the standard model expectations

    Measurement of B-s(0) and D-s(-) Meson Lifetimes

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    We report on a measurement of the flavor-specific B 0 s lifetime and of the D − s lifetime using proton-proton collisions at center-of-mass energies of 7 and 8 TeV, collected by the LHCb experiment and corresponding to 3.0     fb − 1 of integrated luminosity. Approximately 407 000 B 0 s → D ( * ) − s ÎŒ + Îœ ÎŒ decays are partially reconstructed in the K + K − π − ÎŒ + final state. The B 0 s and D − s natural widths are determined using, as a reference, kinematically similar B 0 → D ( * ) − ÎŒ + Îœ ÎŒ decays reconstructed in the same final state. The resulting differences between widths of B 0 s and B 0 mesons and of D − s and D − mesons are Δ Γ ( B ) = − 0.0115 ± 0.0053 ( stat ) ± 0.0041 ( syst )     ps − 1 and Δ Γ ( D ) = 1.0131 ± 0.0117 ( stat ) ± 0.0065 ( syst )     ps − 1 , respectively. Combined with the known B 0 and D − lifetimes, these yield the flavor-specific B 0 s lifetime, τ fs B 0 s = 1.547 ± 0.013 ( stat ) ± 0.010 ( syst ) ± 0.004 ( τ B )     ps and the D − s lifetime, τ D − s = 0.5064 ± 0.0030 ( stat ) ± 0.0017 ( syst ) ± 0.0017 ( τ D )     ps . The last uncertainties originate from the limited knowledge of the B 0 and D − lifetimes. The results improve upon current determinations

    Measurement of the B0s→Ό+Ό− Branching Fraction and Effective Lifetime and Search for B0→Ό+Ό− Decays

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    See paper for full list of authors - All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-001.html - Submitted to Phys. Rev. Lett.International audienceA search for the rare decays B0s→Ό+Ό− and B0→Ό+Ό− is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb−1. An excess of B0s→Ό+Ό− decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B0s→Ό+Ό−)=(3.0±0.6+0.3−0.2)×10−9, where the first uncertainty is statistical and the second systematic. The first measurement of the B0s→Ό+Ό− effective lifetime, τ(B0s→Ό+Ό−)=2.04±0.44±0.05 ps, is reported. No significant excess of B0→Ό+Ό− decays is found and a 95 % confidence level upper limit, B(B0→Ό+Ό−)<3.4×10−10, is determined. All results are in agreement with the Standard Model expectations

    Observation of Five New Narrow Omega(0)(c) States Decaying to Xi K-+(c)-

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    The Ξc+K−\Xi_c^+ K^- mass spectrum is studied with a sample of pppp collision data corresponding to an integrated luminosity of 3.3 fb−1^{-1}, collected by the LHCb experiment. The Ξc+\Xi_c^+ is reconstructed in the decay mode pK−π+p K^- \pi^+. Five new, narrow excited Ωc0\Omega_c^0 states are observed: the Ωc(3000)0\Omega_c(3000)^0, Ωc(3050)0\Omega_c(3050)^0, Ωc(3066)0\Omega_c(3066)^0, Ωc(3090)0\Omega_c(3090)^0, and Ωc(3119)0\Omega_c(3119)^0. Measurements of their masses and widths are reported.Comment: 14 pages, 3 figures. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-002.htm

    Measurement of B0B^0, Bs0B^0_s, B+B^+ and Λb0\Lambda^0_b production asymmetries in 7 and 8 TeV proton-proton collisions

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    See paper for full list of authors - All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-062.html - Submitted to Phys. Lett. B.International audienceThe B0, B0s, B+ and Λ0b hadron production asymmetries are measured using a data sample corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. The measurements are performed as a function of transverse momentum and rapidity of the b hadrons within the LHCb detector acceptance. The overall production asymmetries, integrated over transverse momentum and rapidity, are also determined
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