An angular analysis of B0-->J/psiK(*0) and B(0)(s)-->J/psistraight phi has been used to determine the decay amplitudes with parity-even longitudinal ( A0) and transverse ( A( parallel)) polarization ...and parity-odd transverse ( A( perpendicular)) polarization. The measurements are based on 190 B0 and 40 B(0)(s) candidates obtained from 89 pb(-1) of p collisions at the Fermilab Tevatron. The longitudinal decay amplitude dominates with |A0|(2) = 0.59+/-0. 06+/-0.01 for B0 and |A0|(2) = 0.61+/-0.14+/-0.02 for B(0)(s) decays. The parity-odd amplitude is found to be small with |A( perpendicular)|(2) = 0.13(+0.12)(-0.09)+/-0.06 for B0 and |A( perpendicular)|(2) = 0.23+/-0.19+/-0.04 for B(0)(s) decays.
The photoproduction reaction
γp→
μ
+μ
−p
has been studied in
ep interactions using the ZEUS detector at HERA. The data sample corresponds to an integrated luminosity of
43.2
pb
−1
. The
ϒ meson has ...been observed in photoproduction for the first time. The sum of the products of the elastic
ϒ(1
S),
ϒ(2
S),
ϒ(3
S) photoproduction cross sections with their respective branching ratios is determined to be 13.3±6.0(
stat.)
+2.7
−2.3(
syst.) pb at a mean photon-proton centre of mass energy of 120 GeV. The cross section is above the prediction of a perturbative QCD model.
This Letter describes a direct measurement of the W boson total decay width, gamma(W), using the Collider Detector at Fermilab. The measurement uses an integrated luminosity of 90 pb(-1), collected ...during the 1994-1995 run of the Fermilab Tevatron p collider. The width is determined by normalizing predicted signal and background distributions to 49 844 W-->enu candidates and 21 806 W--> nu candidates in the transverse-mass region M(T)<200 GeV and then fitting the predicted shape to the 438 electron events and 196 muon events in the high- M(T) region, 100<M(T)<200 GeV. The result is gamma(W) = 2.04+/-0.11(stat)+/-0.09(syst) GeV.
We perform a new calculation of the hadronic contributions, \(a({\rm Hadronic})\) to the anomalous magnetic moment of the muon, \(a_\mu\). For the low energy contributions of order \(\alpha^2\) we ...carry over an analysis of the pion form factor \(F_\pi(t)\) using recent data both on \(e^+e^-\to\pi^+\pi^-\) and \(\tau^+\to \bar{\nu}_\tau \pi^+\pi^0\). In this analysis we take into account that the phase of the form factor is equal to that of \(\pi\pi\) scattering. This allows us to profit fully from analyticity properties so we can use also experimental information on \(F_\pi(t)\) at spacelike \(t\). At higher energy we use QCD to supplement experimental data, including the recent measurements of \(e^+e^-\to {\rm hadrons}\) both around 1 GeV and near the \(\bar{c}c\) threshold. This yields a precise determination of the \(O(\alpha^2)\) and \(O(\alpha^2)+O(\alpha^3)\) hadronic part of the photon vacuum polarization pieces, $$10^{11}\times a^{(2)}({\rm h.v.p.})=6 909\pm64;\quad 10^{11}\times a^{(2+3)}({\rm h.v.p.})=7 002\pm66$$ As byproducts we also get the masses and widths of the \(\rho^0, \rho^+\), and very accurate values for the charge radius and second coefficient of the pion. Adding the remaining order \(\alpha^3\) hadronic contributions we find $$10^{11}\times a^{\rm theory}(\hbox{Hadronic})= 6 993\pm69\quad(e^+e^- + \tau + {\rm spacel.})$$ The figures given are obtained including \(\tau\) decay data. This is to be compared with the recent experimental value, $$10^{11}\times a^{\rm exp.}(\hbox{Hadronic})=7 174\pm150.$$
We perform a new, detailed calculation of the hadronic contributions to the running electromagnetic coupling, \(\bar{\alpha}\), defined on the Z particle (91 GeV). We find for the hadronic ...contribution, including radiative corrections, $$10^5\times \deltav_{\rm had.}\alpha(M_Z^2)= 2740\pm12,$$ or, excluding the top quark contribution, $$10^5\times \deltav_{\rm had.}\alpha^{(5)}(M_Z^2)= 2747\pm12.$$ Adding the pure QED corrections we get a value for the running electromagnetic coupling of $$\bar{\alpha}_{\rm Q.E.D.}(M_Z^2)= {{1}\over{128.965\pm0.017}}.$$
We use 106 pb (-1) of data collected with the Collider Detector at Fermilab to search for narrow-width, vector particles decaying to a top and an antitop quark. Model independent upper limits on the ...cross section for narrow, vector resonances decaying to t are presented. At the 95% confidence level, we exclude the existence of a leptophobic Z' boson in a model of top-color-assisted technicolor with mass M(Z')<480 GeV/c(2) for natural width gamma = 0.012M(Z'), and M(Z')<780 GeV/c(2) for gamma = 0.04M(Z').
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