The p¯p total inelastic cross section has been measured in a hydrogen bubble chamber for p¯ momenta from 100 to 550 MeV/c. Below 200 MeV/c the cross section increases rapidly to several barns. From this behavior it is inferred that high partial waves, perhaps to L=3, are important in the annihilation at the lowest momenta studied. An abrupt change in the momentum dependence of the total absorption cross section occurs at about 350 MeV/c in the vicinity of previously observed structure in backward elastic scattering.
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We report here additional positive results of a search for muonless neutrino- and anti-neutrino-induced events using an enriched antineutrino beam and a muon identifier of relatively high geometric detection efficiency. The ratio of muonless to muon event rates is observed to be R=0.20±0.05. We observe no background derived from ordinary neutrino or antineutrino interactions that is capable of explaining the muonless signal.
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This paper presents the final results on charged-current neutrino and antineutrino interactions with nuclei from experiment E-310 at Fermi National Accelerator Laboratory. The data sample, consisting of 21 578 neutrino-induced and 7358 antineutrino-induced events within the fiducial region in the energy range 20<E<325 GeV, is exhibited first to demonstrate the basic properties and kinematic regions represented. The dependence of the nucleon structure functions on the dimensionless variable x and on neutrino energy is then described. Lastly, the variations of the structure functions with x and Q2 are presented. The emphasis throughout has been to understand the effects on the final results of uncertainties in the systematic corrections required by the data. Comparisons with the results of other neutrino experiments are made.
VALUES OF Q2 ARE .36,1.07,2.13,3.56,4.98,6.40,7.82,9.24.
VALUES OF Q2 ARE .70,2.11,4.22,7.04,9.86,12.67,15.49,18.30.
VALUES OF Q2 ARE 1.16,3.48,6.97,11.61,16.26,20.90,25.55,30.19.
Analysis of 5180 ν¯ interactions shows a variation with energy of the inelasticity (y) distributions over the range 10 to 220 GeV and a dependence on the scaling variable x. From these data are obtained the approximate x dependence of the sea quarks and a limit on the strength of right-handed coupling between the u quark and a massive b quark.
Relative rates for deep inelastic neutrino and antineutrino scattering without a finalstate muon have been measured. For neutrinos the result is Rν=σ(νμ+nucleon→νμ+hadrons)σ(νμ+nucleon→μ−+hadrons)=0.11±0.05. The corresponding ratio for antineutrinos is Rν¯=0.32±0.09.
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A search is presented for lepton-flavor violating decays of the Higgs boson to $\mu\tau$ and e$\tau$. The data set corresponds to an integrated luminosity of 137 fb$^{-1}$ collected at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. No significant excess has been found, and the results are interpreted in terms of upper limits on lepton-flavor violating branching fractions of the Higgs boson. The observed (expected) upper limits on the branching fractions are, respectively, $\mathcal{B}($H $\to\mu\tau)$$\lt$ 0.15 (0.15)% and $\mathcal{B}($H$\to$e$\tau)$ $\lt$ 0.22 (0.16)% at 95% confidence level.
Observed (expected) 95% CL upper limits on $B(H\to\mu\tau)$ for each individual category and combined
Observed (expected) 95% CL upper limits on $B(H\to e\tau)$ for each individual category and combined
Summary of observed and expected upper limits at 95% CL, best fit branching fractions and corresponding constraints on Yukawa couplings for the $H\to\mu\tau$ and $H\to e\tau$ channels
Evidence for the backward production of the B(1235) meson in the final state π+p→pfπ+ω at 11.46 GeV/c with σ(|u′|<1.5 GeV2)=1.28±0.26 μb is presented. When nucleon exchange is assumed to dominate, estimates for the SU(3) mixing parameter FD as well as the B coupling to the nucleon-antinucleon are given. Some indication of a narrow enhancement at M(π+ω)≃1.03 GeV/c2 is seen, but confirmation of this as a resonant state is not yet possible.
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We present the xF and pT differential cross sections of J/ψ and ψ′, respectively, in the ranges −0.05<xF<0.25 and pT<3.5 GeV/c. The data samples are constituted by about 12 000 J/ψ and 200 ψ′ produced in proton-silicon interactions at 800 GeV/c and decaying into opposite sign muons. The xF and pT distributions are compared with recent results from experiments E789 at the same energy and to leading order QCD predictions using the MRS D0 parametrization for the parton structure function. The measured shapes of the differential cross sections, except for the dσ/dxF at small xF, agree very well with the prediction, even though their value is quite a bit larger than the prediction. We also present the cosθ differential cross section of the J/ψ which indicates unpolarized production in contrast with color octet models predictions.
Additional systematic error given above.
Additional systematic error given above.
Additional systematic error given above.
The cross sections for the hadroproduction of the Chi1 and Chi2 states of charmonium in proton-silicon collisions at sqrt{s}=38.8 GeV have been measured in Fermilab fixed target Experiment 771. The Chi states were observed via their radiative decay to J/psi+gamma, where the photon converted to e+e- in the material of the spectrometer. The measured values for the Chi1 and Chi2 cross sections for x_F>0 are 263+-69(stat)+-32(syst) and 498+-143(stat)+-67(syst) nb per nucleon respectively. The resulting sigma(Chi1}/sigma(Chi2) ratio of 0.53+-0.20(stat)+-0.07(syst), although somewhat larger than most theoretical expectations, can be accomodated by the latest theoretical estimates.
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The cross section for bb¯ production in 800GeV/c pN interactions has been measured in Fermilab experiment E771 to be 43−17+27(stat)−7+7(syst)nb per nucleon from the observation of events in which both the b and the b¯ decay semimuonically or a B decays into a J/ψ followed by J/ψ→μ+μ−.
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