The polarizations of the Y(1S), Y(2S), and Y(3S) mesons are measured in proton-proton collisions at sqrt(s) = 7 TeV, using a data sample of Y(nS) to oppositely charged muon pair decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters lambda[theta], lambda[phi], and lambda[theta,phi], as well as the frame-invariant quantity lambda-tilde, are presented as a function of the Y(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges abs(y) < 0.6 and 0.6 < abs(y) < 1.2. No evidence of large transverse or longitudinal polarizations has been seen in the explored kinematic region.
Distribution of Lambda-Theta in the CS frame for Y(1S) production in the |y| range 0.0-0.6.
Distribution of Lambda-Theta in the CS frame for Y(1S) production in the |y| range 0.6-1.2.
Distribution of Lambda-Phi in the CS frame for Y(1S) production in the |y| range 0.0-0.6.
A measurement is presented of inelastic photo- and electroproduction of J/psi mesons in ep scattering at HERA. The data were recorded with the H1 detector in the period from 2004 to 2007. Single and double differential cross sections are determined and the helicity distributions of the J/psi mesons are analysed. The results are compared to theoretical predictions in the colour singlet model and in the framework of non-relativistic QCD. Calculations in the colour singlet model using a k_T factorisation ansatz are able to give a good description of the data, while colour singlet model calculations to next-to-leading order in collinear factorisation underestimate the data.
Measured differential photoproduction cross section as a function of the squared transverse momentum of the J/PSI.
Measured differential photoproduction cross section as a function of the elasticity of the J/PSI.
Measured photoproduction cross section as a function of the photon-proton centre of mass energy W.
We have measured the polarizations of J/ψ and ψ(2S) mesons as functions of their transverse momentum pT when they are produced promptly in the rapidity range |y|<0.6 with pT≥5 GeV/c. The analysis is performed using a data sample with an integrated luminosity of about 800 pb−1 collected by the CDF II detector. For both vector mesons, we find that the polarizations become increasingly longitudinal as pT increases from 5 to 30 GeV/c. These results are compared to the predictions of nonrelativistic quantum chromodynamics and other contemporary models. The effective polarizations of J/ψ and ψ(2S) mesons from B-hadron decays are also reported.
Polarization parameter ALPHA for J/PSI production.
Polarization parameter ALPHA for PSI(2S) production.
We report results of the first measurements of Lambda and Antilambda polarization produced in deep inelastic polarized muon scattering on the nucleon. The results are consistent with an expected trend towards positive polarization with increasing x_F. The polarizations of Lambda and Antilambda appear to have opposite signs. A large negative polarization for Lambda at low positive x_F is observed and is not explained by existing models.A possible interpretation is presented.
The measured and corrected (undiluted) polarizations.
The measured and corrected (undiluted) polarizations.
The reaction $\gamma p \rightarrow \omega p$ $(\omega \rightarrow \pi~+\pi~-\pi~0$ and $\pi~0\rightarrow\gamma\gamma)$ has been studied in $ep$ interactions using the \mbox{ZEUS} detector at photon-proton centre-of-mass energies between $70$ and $90\uni{GeV}$ and $|t| < 0.6\uni{GeV}~2$, where $t$ is the squared four momentum transferred at the proton vertex. The elastic \ome photoproduction cross section has been measured to be $\sigma_{\gamma p\rightarrow \omega p} = 1.21\pm 0.12\pm 0.23 \mu\mbox{b}$. The differential cross section $d\sigma_{\gamma p\rightarrow \omega p} /d|t|$ has an exponential shape $\mbox{e}~{-b |t|}$ with a slope $b = 10.0\pm 1.2\pm 1.3\uni{GeV}~{-2}$. The angular distributions of the decay pions are consistent with {\it s}-channel helicity conservation. When compared to low energy data, the features of $\omega$ photoproduction as measured at HERA energies are in agreement with those of a soft diffractive process. Previous measurements of the $\rho~0$ and $\phi$ photoproduction cross sections at HERA show a similar behaviour.
Total Elastic Cross Section.
No description provided.
SLOPE OF DSIG/DT distribution.
The polarization of Lambda0, AntiLambda0, Sigma+ and Xi- inclusively produced in Sigma- induced interactions at 330 GeV has been measured in the experiment WA89 at CERN. This is the first measurement of polarization of baryons produced by a hyperon beam. No polarization of AntiLambda is observed, as was also the case in proton beam data. At transverse momenta of about 1GeV/c Lambda0 and Sigma+ show little polarization, significantly lower than in the proton beam data, while Xi- have a polarization comparable to the polarization of Lambda0 produced in proton beams.
Target Consisted of a copper and a carbon block arranged side by side.
Target Consisted of a copper and a carbon block arranged side by side.
Target Consisted of a copper and a carbon block arranged side by side.
Data are presented for the left-right asymmetry in inclusive production of π+, π−, and p with proton beams (polarized normal to the scattering plane) of 13.3 and 18.5 GeV/c incident on a LH2 target. At both energies the asymmetry in π+ production grows steadily to about 25% near the kinematic limit, whereas the π− and p asymmetries are consistent with zero over the measured range of pt, 1.1–2.2 GeV/c.
No description provided.
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Results are presented on the inclusive photoproduction of λ and λ for incident photon energies between 25 and 70 GeV. The slope parameter of the p T 2 distribution is found to be 2.83±0.1 GeV −2 for λ and 3.28±0.25 GeV −2 for λ . The x F distributions, measured in the range −0.2 to 0.7, show that while λ are produced centrally, λ production extends to more negative values of x F ; the shapes show no energy dependence and are similar to those in pion-induced reactions. The polarization of the produced λ is less than 10%. The results are discussed in terms of vector dominance and quark fusion models.
No description provided.
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Results of measurements of the polarization parameter in K+p elastic scattering at 650, 700, 845, and 940 MeV/c are presented. Details of the measurements are described and results are compared with previous measurements and partial-wave parametrizations of the data. The implication of the existence of Z* resonances in light of these results is discussed.
No description provided.
Results are presented on the properties of the p p interactions at 3.6 GeV/ c leading to a hyperon or an antihyperon in final states with ⩾3 particles from an experiment of 35 eV/μb sensitivity. Results of amultidimensional mass fit to each final state are given along with the cross sections, differential cross sections and polarization, where possible, for the hypercharge exchange reactions p p → Λ Y ∗ (1385), Λ Y ∗ (1520), Σ Y ∗ (1385) and Σ Y ∗ (1520) .
INCOHERENT BREIT-WIGNER RESONANCE FUNCTIONS PLUS PHASE-SPACE FITS TO EACH CHANNEL.
No description provided.
No description provided.
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