124 research outputs found
Digital Computer Modeling of Limestone Groundwater Systems
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 /Ï production in Jets
The production of J/Ï 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/Ï meson, z(J/Ï)âĄpT(J/Ï)/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/Ï)distribution for J/Ï mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/Ï 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/Ï mesons in jets at any experiment
Study of J=Ï Production in Jets
The production of J/Ï 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/Ï meson, z(J/Ï)âĄp[subscript T](J/Ï)/p[subscript T](jet), is measured using jets with p[subscript T](jet) > 20ââGeV in the pseudorapidity range 2.5<η(jet)<4.0. The observed z(J/Ï) distribution for J/Ï mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/Ï 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/Ï mesons in jets at any experiment.National Science Foundation (U.S.
Measurement of the CP asymmetry in B- -> (Ds-D0) and B- -> (D-D0) decays
The CP asymmetry in B- -> (Ds-D0) and B- -> (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- -> (Ds-D0)) = (-0.4 +/- 0.5 +/- 0.5)% and A(CP) (B- -> (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- -> (Ds-D0)) and the most precise determination of A(CP) (B- -> (D-D0)). Neither result shows evidence of CP violation
Search for the decays Bs0âÏ+Ïâ and B0âÏ+Ïâ
A search for the rare decays B0
s â ÏĂŸÏâ and B0 â ÏĂŸÏâ is performed using protonâproton collision data
collected with the LHCb detector. The data sample corresponds to an integrated luminosity of 3 fbâ1
collected in 2011 and 2012. The Ï leptons are reconstructed through the decay Ïâ â ÏâÏĂŸÏâÎœÏ. Assuming
no contribution from B0 â ÏĂŸÏâ decays, an upper limit is set on the branching fraction BĂ°B0
s â ÏĂŸÏâĂ <
6.8 Ă 10â3 at the 95% confidence level. If instead no contribution from B0
s â ÏĂŸÏâ decays is assumed, the
limit is BĂ°B0 â ÏĂŸÏâĂ < 2.1 Ă 10â3 at the 95% confidence level. These results correspond to the first
direct limit on BĂ°B0
s â ÏĂŸÏâĂ and the worldâs best limit on BĂ°B0 â ÏĂŸÏâĂ
Measurement of the B_{s}^{0}âÎŒ^{+}ÎŒ^{-} Branching Fraction and Effective Lifetime and Search for B^{0}âÎŒ^{+}ÎŒ^{-} Decays.
A search for the rare decays B_{s}^{0}âÎŒ^{+}ÎŒ^{-} and B^{0}âÎŒ^{+}ÎŒ^{-} is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4ââfb^{-1}. An excess of B_{s}^{0}âÎŒ^{+}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}âÎŒ^{+}ÎŒ^{-})=(3.0±0.6_{-0.2}^{+0.3})Ă10^{-9}, where the first uncertainty is statistical and the second systematic. The first measurement of the B_{s}^{0}âÎŒ^{+}ÎŒ^{-} effective lifetime, Ï(B_{s}^{0}âÎŒ^{+}ÎŒ^{-})=2.04±0.44±0.05ââps, is reported. No significant excess of B^{0}âÎŒ^{+}ÎŒ^{-} decays is found, and a 95% confidence level upper limit, B(B^{0}âÎŒ^{+}ÎŒ^{-})<3.4Ă10^{-10}, is determined. All results are in agreement with the standard model expectations
Measurement of B-s(0) and D-s(-) Meson Lifetimes
We report on a measurement of the flavor-specific B 0 s lifetime and of the D â 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 â â fb â 1 of integrated luminosity. Approximately 407â000 B 0 s â D ( * ) â s ÎŒ + Îœ ÎŒ decays are partially reconstructed in the K + K â Ï â ÎŒ + final state. The B 0 s and D â s natural widths are determined using, as a reference, kinematically similar B 0 â D ( * ) â 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 â s and D â mesons are Î Î ( B ) = â 0.0115 ± 0.0053 ( stat ) ± 0.0041 ( syst ) â â ps â 1 and Î Î ( D ) = 1.0131 ± 0.0117 ( stat ) ± 0.0065 ( syst ) â â ps â 1 , respectively. Combined with the known B 0 and D â lifetimes, these yield the flavor-specific B 0 s lifetime, Ï fs B 0 s = 1.547 ± 0.013 ( stat ) ± 0.010 ( syst ) ± 0.004 ( Ï B ) â â ps and the D â s lifetime, Ï D â s = 0.5064 ± 0.0030 ( stat ) ± 0.0017 ( syst ) ± 0.0017 ( Ï D ) â â ps . The last uncertainties originate from the limited knowledge of the B 0 and D â lifetimes. The results improve upon current determinations
Measurement of the B0sâÎŒ+ÎŒâ Branching Fraction and Effective Lifetime and Search for B0âÎŒ+ÎŒâ Decays
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 B0sâÎŒ+ÎŒâ and B0âÎŒ+ÎŒâ is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fbâ1. An excess of B0sâÎŒ+ÎŒâ 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(B0sâÎŒ+ÎŒâ)=(3.0±0.6+0.3â0.2)Ă10â9, where the first uncertainty is statistical and the second systematic. The first measurement of the B0sâÎŒ+ÎŒâ effective lifetime, Ï(B0sâÎŒ+ÎŒâ)=2.04±0.44±0.05 ps, is reported. No significant excess of B0âÎŒ+ÎŒâ decays is found and a 95 % confidence level upper limit, B(B0âÎŒ+ÎŒâ)<3.4Ă10â10, 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)-
The mass spectrum is studied with a sample of collision
data corresponding to an integrated luminosity of 3.3 fb, collected by
the LHCb experiment. The is reconstructed in the decay mode . Five new, narrow excited states are observed: the
, , , ,
and . 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 , , and production asymmetries in 7 and 8 TeV proton-proton collisions
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 Î0b hadron production asymmetries are measured using a data sample corresponding to an integrated luminosity of 3.0 fbâ1, 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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