We have observed $23.2 \pm 6.0_{-0.9}^{+1.0}$ purely-leptonic decays of $D_s^+ -> \mu^+ \nu_\mu$ from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the $D_s^+ -> \phi \mu^+ \nu_\mu$ yield measured previously in this experiment, we obtain $B(D_s^+ --> \mu^+ \nu_\mu) / B(D_s^+ --> \phi \mu^+ \nu_\mu) =0.16 \pm 0.06 \pm 0.03$. In addition, we extract the decay constant $f_{D_s}=194 \pm 35 \pm 20 \pm 14 MeV$.
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We have found 122 charmed-particle decays among 3855 neutrino interactions located in the fiducial volume of a hybrid emulsion spectrometer installed in the Fermilab wide-band neutrino beam. We obtain an average relative charmed-particle production cross section of σ(ν μ → c μ − ) σ(ν μ →μ − ) =4.9 −0.6 +0.7 % , at an average neutrino energy of 22 GeV. We also obtain a production rate of σ(ν μ → c c ν μ ) σ(ν μ →ν μ ) =0.13 −0.11 +0.31 % , if we assume that there was an undetected muon, a limit of σ(ν μ → c c μ − ) σ(ν μ → c μ − )<3% (90% CL ) can be obtained. Other cross section ratios and limits are also presented.
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We present a measurement of angular observables, $P_4'$, $P_5'$, $P_6'$, $P_8'$, in the decay $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$, where $\ell^+\ell^-$ is either $e^+e^-$ or $\mu^+\mu^-$. The analysis is performed on a data sample corresponding to an integrated luminosity of $711~\mathrm{fb}^{-1}$ containing $772\times 10^{6}$ $B\bar B$ pairs, collected at the $\Upsilon(4S)$ resonance with the Belle detector at the asymmetric-energy $e^+e^-$ collider KEKB. Four angular observables, $P_{4,5,6,8}'$ are extracted in five bins of the invariant mass squared of the lepton system, $q^2$. We compare our results for $P_{4,5,6,8}'$ with Standard Model predictions including the $q^2$ region in which the LHCb collaboration reported the so-called $P_5'$ anomaly.
Results of the angular analysis of $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$ (where $\ell = e,\mu$) in five bins of $q^2$, the di-lepton invariant mass squared.
A high-statistics measurement of the differential cross-sections for neutrino-iron scattering in the wide-band neutrino beam at the CERN SPS is presented. Nucleon structure functions are extracted and theirQ2 evolution is compared with the predictions of quantum chromodynamics.
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We present an analysis of electroweak leptonic couplings from high statistics experiments on Bhabha scattering and μ pair production at an energy of 34.5 GeV. The forward-backward charge asymmetry of the μ pairs was measured to be −0.098±0.023±0.005. The data were found to agree well with the standard theory of electroweak interaction giving sin2θW=0.27±0.07. The leptonic weak couplings were determined to begv=0.000±0.170 andgA=−0.481±0.055. The data were also used to investigate a class of composite models for leptons.
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We report a high-precision measurement of the ratio R of the total cross section for e+e−→hadrons to that for e+e−→μ+μ−, at a center-of-mass energy of 29.0 GeV using the MAC detector. The result is R=3.96±0.09. This value of R is used to determine a value of the strong coupling constant αs of 0.23±0.06, nearly independent of fragmentation models. Two different analysis methods having quite different event-selection criteria have been used and the results are in agreement. Particular attention has been given to the study of systematic errors. New higher-order QED calculations are used for the luminosity determination and the acceptance for hadrons.
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We have measured the process e+e−→μ+μ− at √s =29 GeV using the High Resolution Spectrometer at SLAC PEP. The forward-backward charge asymmetry is Aμμ=-(4.9±1.5±0.5)% based on 5057 events. A subsample of 3488 μ+μ− events in the angular range ‖cosθ‖<0.55 gives a cross-section ratio of Rμμ=0.990±0.017±0.030. The resulting couplings of the weak neutral current are gaegaμ=0.208±0.064± 0.021 and gvegvμ=0.027 ±0.051±0.089. The QED cutoff parameters are Λ+>170 GeV and Λ−>146 GeV at 95% C.L.
Corrected for acceptance and O(alpha**3) QED radiation. Numerical values taken from SUGANO-ANL-HEP-CP-84-90.
Forward-backward asymmetry based on fit to angular distribution. Result is given combined with earlier data from BENDER et al.
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We have studied the production of prompt muons in hadronic events from e+e− annihilation at a center-of-mass energy of 29 GeV with the PEP4-TPC (Time Projection Chamber) detector. The muon p and pt distributions are well described by a combination of bottom- and charm-quark decays, with fitted semimuonic branching fractions of (15.2±1.9±1.2)% and (6.9±1.1±1.1)%, respectively. The muon spectra imply hard fragmentation functions for both b and c quarks, with 〈z(b quark)〉=0.80±0.05±0.05 and 〈z(c quark)〉=0.60±0.06±0.04. We derive neutral-current axial-vector couplings of a(b quark)=-0.9±1.1±0.3 and a(c quark)=1.5±1.5±0.5 from the forward-backward asymmetries.
PT is the transverse momentum of the muon relative to the event thrust axis.
PT is the transverse momentum of the MUON relative to the event thrust axis. At this table MUON is from JET and its PT < 1 GeV/c.
PT is the transverse momentum of the MUON relative to the event thrust axis. At this table MUON is from JET and its PT > 1 GeV/c.
The Fermilab hybrid 30-in. bubble-chamber spectrometer was exposed to a tagged 147-GeV/c positive beam containing π+, K+, and p. A sample of 3003 K+p, 19410 pp, and 20745 π+p interactions is used to derive σn, 〈n〉, f2cc, and 〈nc〉D for each beam particle. These values are compared to values obtained at other, mostly lower, beam momenta. The overall dependence of 〈n〉 on Ea, the available center-of-mass energy, for these three reactions as well as π−p and pp interactions has been determined.
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Light ion collisions with carbon target at 4.2 GeV/c/N are studied. Pion multiplicity distributions, momentum and angular spectra are analysed. These data are described in terms of models assuming independent interactions of nucleons from the projectile nucleus with the target.
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