Two samples of exclusive semileptonic decays, 579 B 0 → D ∗+ ℓ − ν ℓ events and 261 B 0 → D + ℓ − ν ℓ events, are selected from approximately 3.9 million hadronic Z decays collected by the ALEPH detector at LEP. From the reconstructed differential decay rate of each sample, the product of the hadronic form factor F (ω) at zero recoil of the D (∗)+ meson and the CKM matrix element | V cb | are measured to be F D ∗+ (1)|V cb | = (31.9 ± 1.8 stat ± 1.9 syst ) × 10 −3 , F D + (1)| V cb | = (27.8 ± 6.8 stat ± 6.5 syst ) × 10 −3 . The ratio of the form factors F D + (1) and F D ∗+ (1) is measured to be F D + (1) F D ∗+ (1) = 0.87 ± 0.22 stat ± 0.21 syst . A value of | V cb | is extracted from the two samples, using theoretical constraints on the slope and curvature of the hadronic form factors and their normalization at zero recoil, with the result | V cb | = (34.4 ± 1.6 stat ± 2.3 syst ± 1.4 th ) × 10 −3 . The branching fractions are measured from the two integrated spectra to be Br ( B 0 → D ∗+ ℓ − ν ℓ ) = (5.53 ± 0.26 stat ±0.52 syst ) %, Br ( B 0 → D ∗+ ℓ − ν ℓ ) = (2.35 ± 0.20 stat ± 0.44 syst ) %.
The formfactors are evaluated at zero recoil of D meson. Two different methods are used (see text for details). VCB is the KCM matrix element. The formfactor fitted to dependence: FF(OM) = FF(1)*(1-CONST*(OM-1)).
VCB is the KCM matrix element.
VCB is the KCM matrix element.
We present results on flux-normalized neutrino and antineutrino cross sections near y=0 from data obtained in the Fermilab narrow-band beam. We conclude that values of σ0=dσdy|y=0 are consistent with rising linearly with energy over the range 45<~Eν<~20.5 GeV. The separate averages of ν and ν¯, each measured to 4%, are equal to well within the errors. The best fit for the combined data gives σ0E=(0.719±0.035)×10−38 cm2/GeV at an average Eν of 100 GeV.
FE nucleus. The SIG/Enu is fitted to CONST(N=SIG)+CONST(N=T)*E.
FE nucleus. Averaged over the energies and beams.
We present the first experimental study of the ratio of cumulant to factorial moments of the charged-particle multiplicity distribution in high-energy particle interactions, using hadronic Z$^0$ decays collected by the SLD experiment at SLAC. We find that this ratio, as a function of the moment-rank $q$, decreases sharply to a negative minimum at $q=5$, which is followed by quasi-oscillations. These features are insensitive to experimental systematic effects and are in qualitative agreement with expectations from next-to-next-to-leading-order perturbative QCD.
CONST is the cumulant to factorial moments ratio. See text for definition.
We present a measurement and comparison of the χc1 and χc2 production cross sections determined from interactions of 300-GeV/c π± and p with a Li target. We find χc1χc2 production ratios of 0.52−0.27+0.57 and 0.08−0.15+0.25 from reactions induced by π± and p, respectively.
The cross section per nucleon.
The cross section per nucleon. The differential cross section is fitted by the equation : D(SIG)/D(PT**2)= CONST*EXP(SLOPE*PT), D(SIG)/D(XL) = CONST*(1-(XL-CONST(C=X0))**2)**POWER(C=1) , and D(SIG)/D(XL) = CONST*(1-ABS(XL-CONST(C=XC)))**POWER(C=2).
The cross section per nucleon. The differential cross section is fitted by the equation : D(SIG)/D(COS(THETA)) = CONST*(1+CONST*COS(THETA)**2), where THETA is the angle between the MU+ and beam momentum in the CHI/C rest frame.
The study of the J ψ transverse momentum distribution in oxygen-uranium reactions at 200 GeV/nucleon shows that 〈 P T 〉 and 〈 P T 2 〉 increase with the transverse energy of the reaction. Muon pairs in the mass continuum do not exhibit the same behaviour. The comparison of the J ψ production rates in central and peripheral collisions shows a significant diminution for low P T central events.
Two parametrization of the D(SIG)/D(PT) are used: first is : PT*exp(-SLOPE*PT**CONST(C=PT)) and second is : PT*exp(-2*MT/CONST(C=MT)).
D(SIG)/D(PT) is parameterized as PT*exp(-SLOPE*PT**CONST).
D(SIG)/D(PT) is parameterized as PT*exp(-SLOPE*PT**CONST).
Using the ARGUS detector at the e + e − storage ring DORIS II at DESY, we have made two measurements of the mixing parameter χ d using kaons as flavour tags. Using D ∗+ K ± correlations we found χ d = 0.20 ± 0.13 ± 0.12 and from the study of (D ∗+ ℓ − ) K ± correlations we obtained χ d = 0.19 ± 0.07 ± 0.09. The branching ratio for B → D ∗+ X has been updated: Br( B → D ∗+ X) = (19.6 ± 1.9) %. We have also determined the average multiplicity of charged kaons in B 0 decays to be 0.78 ± 0.08.
Mixing parameter from counting kaon events. First (...,C=D*+K+-) and second(...,C=(D*+LEPTON-)K+-) value are obtained from a study of D*+K+- and (D*+LEPTO N-)K+- correlations respectively. Second value and the value, reported in Phys.Lett. 324B (1994) 249, were averaged, result third value (...,C=COMBINED) of the mixing parameter in the table (see text for details). In the second value (...,C=(D*+LEPTON-)K+-) the first systematic error is due to the background estimation, the branching ratio for the process B --> K+(K-) X, experimental cuts, and the second one is due to to the uncertainty on the branching ratio for the processes D0 --> K+- X.
No description provided.
The Beijing Spectrometer (BES) experiment has observed purely leptonic decays of the Ds meson in the reaction e+e−→Ds+Ds− at a c.m. energy of 4.03 GeV. Three events are observed in which one Ds decays hadronically to φπ, K¯*0K, or K¯0K, and the other decays leptonically to μνμ or τντ. With the assumption of μ−τ universality, values of the branching fraction, B(Ds→μνμ)=(1.5−0.6−0.2+1.3+0.3)%, and the Ds pseudoscalar decay constant, fDs=(4.3−1.3−0.4+1.5+0.4)×102 MeV, are obtained.
No description provided.
In this table CONST is the pseudoscalar decay constant, f_[D/S].
We present results from CDF and D\O\ on $W\gamma$ and $Z\gamma$ productions in $p\bar{p}$ collisions at $\sqrt{s}=1.8{\rm TeV}.$ The goal of the analyses is to test the non-abelian self-couplings of the $W$, $Z$ and photon, one of the most direct consequences of the $SU(2)_L\otimes U(1)_Y$ gauge symmetry. We present direct measurements of $WW\gamma$ couplings and limits on $ZZ\gamma$ and $Z\gamma\gamma$ couplings, based on $p\bar{p}\rightarrow \ell\nu\gamma + X$ and $p\bar{p}\rightarrow \ell\ell\gamma+X$ events, respectively, observed during the 1992--1993 run of the Fermilab Tevatron Collider.
CDF data.. DELTA(R) = SQRT( DELTA(ETARAP(LEPTON,GAMMA))**2 + DELTA(PHI(LEPTON,GAMMA))**2 ) > 0.7.
CDF data.. DELTA(R) = SQRT( DELTA(ETARAP(LEPTON,GAMMA))**2 + DELTA(PHI(LEPTON,GAMMA))**2 ) > 0.7.
CDF data.. E + MU combined. Limits on CP-conserving anomalous WWGAMMA couplings DELTA(K) and LAMBDA (see paper). Limits on CP-violating parameters are within 3-6% of obtained.
Momenta of charged particles produced in inelastic αα, αp, andpp collisions were measured using the Split-Field-Magnet detector at the CERN Intersecting Storage Rings. Inclusive and semi-in-clusive spectra are presented as a function of rapidityy, Feynman-x, and transverse momentumpT. The inclusivey distributions agree well with predictions of the dual parton model; the highest particle densities are reached aty≃0 and the momenta of leading protons decrease significantly for increasing total multiplicity. ‘Temperatures’ are equal in αα, αp, andpp interactions. ThepT distributions depend weakly on the multiplicity.
No description provided.
No description provided.
No description provided.
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