We present a new formulation of one of the major radiative corrections to the weak charge of the proton-that arising from the axial-vector hadron part of the γZ box diagram, ℜe□(γZ)(A). This ...formulation, based on dispersion relations, relates the γZ contributions to moments of the F(3)(γZ) interference structure function. It has a clear connection to the pioneering work of Marciano and Sirlin, and enables a systematic approach to improved numerical precision. Using currently available data, the total correction from all intermediate states is ℜe□(γZ)(A)=0.004 4(4) at zero energy, which shifts the theoretical estimate of the proton weak charge from 0.071 3(8) to 0.070 5(8). The energy dependence of this result, which is vital for interpreting the Q(weak) experiment, is also determined.
The D0 Silicon Microstrip Tracker Ahmed, S.N.; Aoki, M.; Åsman, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2011, Letnik:
634, Številka:
1
Journal Article
Recenzirano
This paper describes the mechanical design, the readout chain, the production, testing and the installation of the Silicon Microstrip Tracker of the D0 experiment at the Fermilab Tevatron collider. ...In addition, we describe the performance and operational experience of the detector during the experiment data collection between 2001 and 2010.
We present a measurement of the forward-backward asymmetry in the production of B(±) mesons, A(FB)(B(±)), using B(±)→J/ψK(±) decays in 10.4 fb(-1) of pp̄ collisions at sqrts=1.96 TeV collected by ...the D0 experiment during Run II of the Tevatron collider. A nonzero asymmetry would indicate a preference for a particular flavor, i.e., b quark or ̄b antiquark, to be produced in the direction of the proton beam. We extract A(FB)(B(±)) from a maximum likelihood fit to the difference between the numbers of forward- and backward-produced B(±) mesons. We measure an asymmetry consistent with zero: A(FB)(B(±))=-0.24±0.41 (stat)±0.19 (syst)%.
We present the first measurements of the ratios of cross sections σ(pp → Z+c jet)/σ(pp → Z+jet) and σ(pp → Z+c jet)/σ(pp → Z+b jet) for the associated production of a Z boson with at least one charm ...or bottom quark jet. Jets have transverse momentum pT(jet)>20 GeV and pseudorapidity |η(jet)|<2.5. These cross section ratios are measured differentially as a function of jet and Z boson transverse momenta, based on 9.7 fb(-1) of pp collisions collected with the D0 detector at the Fermilab Tevatron Collider at √s=1.96 TeV. The measurements show significant deviations from perturbative QCD calculations and predictions from various event generators.
A
bstract
We explore the sensitivity of
W
and
Z
boson production in hadronic collisions to uncertainties in parton distribution functions (PDFs) at large
x
arising from uncertainties in nuclear ...corrections when using deuterium data in global QCD fits. The
W
and
Z
differential cross sections show increasing influence of nuclear corrections at high boson rapidities, particularly for the
d
quark, which is diluted somewhat in the decay lepton rapidity distributions. The effects of PDF uncertainties on heavy
W
′ and
Z
′ bosons beyond the Standard Model become progressively more important for larger boson masses or rapidities, both in
pp
collisions at the LHC and in
scattering at the Tevatron.
We present measurements of the differential cross section dσ/dργτ for the inclusive production of a photon in association with a b -quark jet for photons with rapidities |yγ| < 1.0 and 30 < ργτ < 300 ...GeV , as well as for photons with 1.5 <|yγ| < 2.5 and 30 < ργτ < 200 GeV, where ργτ is the photon transverse momentum. The b -quark jets are required to have pT > 15 GeV and rapidity |yjet| < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb-1, recorded with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider at $\sqrt{s}$ =1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the SHERPA and PYTHIA Monte Carlo event generators.
We present a measurement of the effective weak mixing angle parameter sin^{2}θ_{eff}^{ℓ} in ppover ¯→Z/γ^{*}→μ^{+}μ^{-} events at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at ...the Fermilab Tevatron Collider and corresponding to 8.6 fb^{-1} of integrated luminosity. The measured value of sin^{2}θ_{eff}^{ℓ}μμ=0.23016±0.00064 is further combined with the result from the D0 measurement in ppover ¯→Z/γ^{*}→e^{+}e^{-} events, resulting in sin^{2}θ_{eff}^{ℓ}comb=0.23095±0.00040. This combined result is the most precise measurement from a single experiment at a hadron collider and is the most precise determination using the coupling of the Z/γ^{*} to light quarks.
Evidence for a B_{s}^{0}π^{±} State Adams, M; Adams, T; Alton, A ...
Physical review letters,
2016-Jul-08, 20160708, Letnik:
117, Številka:
2
Journal Article
Recenzirano
We report evidence for a narrow structure, X(5568), in the decay sequence X(5568)→B_{s}^{0}π^{±}, B_{s}^{0}→J/ψϕ, J/ψ→μ^{+}μ^{-}, ϕ→K^{+}K^{-}. This is evidence for the first instance of a hadronic ...state with valence quarks of four different flavors. The mass and natural width of this state are measured to be m=5567.8±2.9(stat)_{-1.9}^{+0.9}(syst) MeV/c^{2} and Γ=21.9±6.4(stat)_{-2.5}^{+5.0}(syst) MeV/c^{2}. If the decay is X(5568)→B_{s}^{*}π^{±}→B_{s}^{0}γπ^{±} with an unseen γ, m(X(5568)) will be shifted up by m(B_{s}^{*})-m(B_{s}^{0})∼49 MeV/c^{2}. This measurement is based on 10.4 fb^{-1} of ppover ¯ collision data at sqrts=1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.
We present a study of the inclusive production of the X(4140) state with the decay to the J/ψϕ final state in hadronic collisions. Based on 10.4 fb^{-1} of ppover ¯ collision data collected by the ...D0 experiment at the Fermilab Tevatron collider, we report the first evidence for the prompt production of an X(4140) state and find the fraction of X(4140) events originating from b hadrons to be f_{b}=0.39±0.07(stat)±0.10(syst). The ratio of the nonprompt X(4140) production rate to the B_{s}^{0} yield in the same channel is R=0.19±0.05(stat)±0.07(syst). The values of the mass M=4152.5±1.7(stat)_{-5.4}^{+6.2}(syst) MeV and width Γ=16.3±5.6(stat)±11.4(syst) MeV are consistent with previous measurements.
We present the first search for CPT-violating effects in the mixing of Bs(0) mesons using the full Run II data set with an integrated luminosity of 10.4 fb(-1) of proton-antiproton collisions ...collected using the D0 detector at the Fermilab Tevatron Collider. We measure the CPT-violating asymmetry in the decay Bs(0)→μ(±)Ds(±) as a function of celestial direction and sidereal phase. We find no evidence for CPT-violating effects and place limits on the direction and magnitude of flavor-dependent CPT- and Lorentz-invariance violating coupling coefficients. We find 95% confidence intervals of Δa⊥<1.2×10(-12) GeV and (-0.8<ΔaT-0.396ΔaZ<3.9)×10(-13) GeV.