The inclusive charged-hadron momentum spectra from the ψ and ψ′ decays produced in e+e− collisions at SPEAR are presented. The data were obtained with a small solid-angle, single-arm magnetic spectrometer with good particle-identification abilities centered at 90 degrees with respect to the beams. The particle-separated invariant cross sections are compared with data from e+e− collisions at s=4.8 and 7.3 GeV, obtained with the same spectrometer, in order to observe the difference between hadron production at the resonances and in the continuum.
AT J/PSI.
AT J/PSI.
AT J/PSI.
We report on inclusive hadron production in e+e− annihilation at 〈s〉=53 GeV2, using a small solid-angle magnetic spectrometer with good particle identification at 90° to the beams at SPEAR II. The cross sections of π± and K± when compared with data at s=23 GeV2 exhibit scaling in (sβ)dσdx with x=2Es12. The invariant cross section depends on the momentum as p−4.
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We present measured hadron energy distributions for the reactions ν(ν¯)+N→ν(ν¯)+hadrons at high energy, as well as for the similar charged-current interactions. Insofar as possible, the determination of these distributions avoids any a priori assumptions about either the neutral-current or the charged-current interactions. We further analyze the neutral-current distributions within the framework of specific models, particularly the scaling model, to obtain a positive-helicity component P=0.36±0.10, which lies between pure V−A and pure V or A, and a coupling strength of g0=0.31±0.03 relative to the charged-current interaction. These coupling parameters agree well with the predictions of the Weinberg-Salam model with sin2θW=0.33±0.07.
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We present results on charged multiplicity nch=2 and nch>2 muon events produced in e+e− collisions with 〈s12〉=7.3 GeV at 90° to the beams. The background-subtracted inclusive cross section for the nch=2 events is 10.2±5.4 pb/sr, in agreement with the expected contribution from the heavy lepton τ. The cross section for the nch>2 events is 19.0±6.5 pb/sr whereas we expect only 2.9 pb/sr from the τ, indicating that we may be seeing the weak decays of charmed mesons.
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The reaction π−+p→Λ+K0 in the 72-in. hydrogen chamber was used to produce 7220 K0 mesons associated with a visible decay Λ→p+π−. The time dependence and absolute yield of the subsequent strong interactions of K0 and K0 in hydrogen were used to determine all the parameters of the neutral K system, without the assumption of CPT invariance or other assumptions about the weak interactions of neutral K's. From the time distribution of 59 events of the type K¯0+p→hyperon, we find the magnitude of the KS0−KL0 mass difference. We then determine the mixing parameters p, q, p′, q′ of the neutral K system by means of the time dependence and absolute yield of 11 charge-exchange events, K0+p→K++n, and the absolute yield of 49 two-body interactions, K¯0+p→hyperon+pion. The results are consistent with CPT invariance and with values of the mixing parameters determined by means of weak interactions. We find the Biswas ratio R≡σ(KLp→KSp)σ(KLp→hyperon) to be R=0.41±0.13 averaged over KL momenta from about 200 to 600 MeVc. This agrees with solution I of Kim and with the results of Kadyk et al. Our absolute yields for K¯0+p→hyperon+pion are in good agreement with the predictions of charge independence and the measured rates for K−+p→hyperon+pion. For the front-back asymmetry of the Λ in K¯0+p→Λ+π+, we find (F−B)(F+B)=−0.48±0.18, indicating that the P wave cannot be neglected relative to the S wave in our momentum range.
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