71,289 research outputs found
Measurement of the differential γ +2b-jet cross section and the ratio σ(γ +2b-jets)/σ(γ +b-jet) in p¯p collisions at √ s = 1.96 TeV
No full textWe present the first measurements of the differential cross section dσ/dpγ T for the production of an isolated photon in association with at least two b-quark jets. The measurements consider photons with rapiditie
Measurement of the W +b-jet and W +c-jet differential production cross sections in p¯p collisions at √s = 1.96 TeV
No full textWe present a measurement of the cross sections for the associated production of a W boson with at least one heavy quark jet, b or c , in proton–antiproton collisions. Data corresponding to an integrated luminosity of 8.7 fb−18.7 fb−1 recorded with the D0 detector at the Fermilab Tevatron View the MathML sourcepp¯ Collider at View the MathML sources=1.96 TeV are used to measure the cross sections differentially as a function of the jet transverse momenta in the range 20 to 150 GeV. These results are compared to calculations of perturbative QCD theory as well as predictions from Monte Carlo generators
Measurement of the pp →W +b + X production cross section at √ s = 1.96 TeV
No full textWe present a measurement of the cross section for W boson production in association with at least one b-quark jet in proton–antiproton collisions. The measurement is made using data corresponding to an integrated luminosity of 6.1 fb−1 recorded with the D0 detector at the Fermilab Tevatron p¯p √ Collider at s = 1.96 TeV. We measure an inclusive cross section of σ(W(→μν) + b + X) = 1.04 ± 0.05 (stat.) ± 0.12 (syst.) pb and σ(W(→eν)+b+ X) = 1.00±0.04 (stat.)±0.12 (syst.) pb in the phase space defined by pνT > 25 GeV, pb-jet T > 20 GeV
Measurement of the ratio of three-jet to two-jet cross sections in p¯p collisions at √ s = 1.96 TeV
No full textWe present a measurement of the ratio of multijet cross sections in p¯p collisions at √ s = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb−1 collected with the D0 detector. The ratio of the inclusive three-jet to two-jet cross sections, R3/2, has been measured as a function of the jet transverse momenta. The data are compared to QCD predictions in different approximations. Popular tunes of the pythia event generator do not agree with the data, while sherpa provides a reasonable description of the data. A perturbative QCD prediction in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects, gives a good description of the data
Measurement of the differential γ +c-jet cross section and the ratio of differential γ +c and γ +b cross sections in p¯p collisions at √ s = 1.96 TeV
No full textWe present measurements of the differential cross section dσ/dpγ T for the associated production of a cquark jet and an isolated photon with rapidit
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
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
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
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
Dielectron and heavy-quark production in inelastic and high-multiplicity proton-proton collisions at = 13 TeV
No full textA Precise measurement of the B0(s) lifetime
No full textThe authors report a measurement of the B{sub s}{sup 0} lifetime in the semileptonic decay channel B{sub s}{sup 0} {yields} D{sub s}{sup -}{mu}{sup +}{nu}X (and its charge conjugate), using approximately 0.4 fb{sup -1} of data collected with the D0 detector during 2002-2004. They have reconstructed 5176 D{sub s}{sup -} {mu}{sup +} signal events, where the D{sub s}{sup -} is identified via the decay D{sub s}{sup 0} {yields} {phi}{pi}{sup -}, followed by {phi} {yields} K{sup +}K{sup -}. Using these events, they have measured the B{sub s}{sup 0} lifetime to be {tau}(B{sub s}{sup 0}) = 1.398 {+-} 0.044 (stat){sub -0.025}{sup +0.028}(syst) ps. This is the most precise measurement of the B{sub s}{sup 0} lifetime to date
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