The eta-prime meson production in the reaction pp-->pp eta-prime has been studied at excess energies of Q = 26.5, 32.5 and 46.6 MeV using the internal beam facility COSY-11 at the cooler synchrotron COSY. The total cross sections as well as one angular distribution for the highest Q-value are presented. The excitation function of the near threshold data can be described by a pure s-wave phase space distribution with the inclusion of the proton-proton final state interaction and Coulomb effects. The obtained angular distribution of the eta-prime mesons is also consistent with pure s-wave production.
Total cross section for the reaction P P --> P P ETAPRIME.
Angular distribution of the ETAPRIME in the CM system at an excess energy of 46.6 MeV. There is an additional systematic error of +24%/-35%.
Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at {\surd}s = 7 TeV in dedicated runs with the Roman Pot detectors placed as close as seven times the transverse beam size (sbeam) from the outgoing beams. After careful study of the accelerator optics and the detector alignment, |t|, the square of four-momentum transferred in the elastic scattering process, has been determined with an uncertainty of d t = 0.1GeV p|t|. In this letter, first results of the differential cross section are presented covering a |t|-range from 0.36 to 2.5GeV2. The differential cross-section in the range 0.36 < |t| < 0.47 GeV2 is described by an exponential with a slope parameter B = (23.6{\pm}0.5stat {\pm}0.4syst)GeV-2, followed by a significant diffractive minimum at |t| = (0.53{\pm}0.01stat{\pm}0.01syst)GeV2. For |t|-values larger than ~ 1.5GeV2, the cross-section exhibits a power law behaviour with an exponent of -7.8_\pm} 0.3stat{\pm}0.1syst. When compared to predictions based on the different available models, the data show a strong discriminative power despite the small t-range covered.
The measured differential elastic cross section. Data from the tabulation in CERN-PH-EP-2012-239.
First exclusive data for the $pp \to nn\pi^+\pi^+$ reaction have been obtained at CELSIUS with the WASA detector setup at a beam energy of $T_p$ = 1.1 GeV. Total and differential cross sections disagree with theoretical calculations, which predict the $\Delta\Delta$ excitation to be the dominant process at this beam energy. Instead the data require the excitation of a higher-lying $\Delta$ state, most likely the $\Delta(1600)$, to be the leading process.
Total cross section.
Distribution of the invariant mass of the PI+PI+ system.
Distribution of the cosine of the PI+_PI+ opening angle DELTA at an incident kinetic energy of 1.1 GeV.
Spectra of positively charged kaons in p+C interactions at 31 GeV/c were measured with the NA61/SHINE spectrometer at the CERN SPS. The analysis is based on the full set of data collected in 2007 with a graphite target with a thickness of 4% of a nuclear interaction length. Interaction cross sections and charged pion spectra were already measured using the same set of data. These new measurements in combination with the published ones are required to improve predictions of the neutrino flux for the T2K long baseline neutrino oscillation experiment in Japan. In particular, the knowledge of kaon production is crucial for precisely predicting the intrinsic electron neutrino component and the high energy tail of the T2K beam. The results are presented as a function of laboratory momentum in 2 intervals of the laboratory polar angle covering the range from 20 up to 240 mrad. The kaon spectra are compared with predictions of several hadron production models. Using the published pion results and the new kaon data, the K+/\pi+ ratios are computed.
The measured K+ production cross section and the K+/PI+ cross section ratio for the angular range 20 to 140 mrad. The errors on the ratios are statistical only.
The measured K+ production cross section and the K+/PI+ cross section ratio for the angular range 140 to 240 mrad. The errors on the ratios are statistical only.
3roton-antiproton elastic scattering at cm energy 540 GeV has been studied in the t range 0.14 ⩽ − t ⩽ 0.26 GeV 2 . The data is well fitted by an exponential form exp( bt ) with b = 13.3 ± 1.5 GeV −2 .
Elastic Differentiaol Cross Section (545 events). DATA REQUESTED 21 FEB 1983. Data read from plot in paper (29 JAN 2015).
No description provided.
We have measured pi+pi- and K+K- production in two-photon collisions using 87.7 /fb of data collected with the Belle detector at the asymmetric energy e+e- collider KEKB. The cross sections are measured to high precision in the two-photon center-of-mass energy (W) range between 2.4 GeV < W < 4.1 GeV and angular region |cos theta^{*}| < 0.6. The cross section ratio sigma(gammagamma->K+K-)/sigma(gammagamma->pi+pi-) is measured to be 0.89 +- 0.04(stat) +- 0.15(syst) in the range of 3.0 GeV < W < 4.1 GeV, where the ratio is energy independent. We observe a sin^{-4} theta^{*} behavior of the cross section in the same W range. Production of chi_{c0} and chi_{c2} mesons is observed in both gammagamma -> pi+pi- and gammagamma -> K+K- modes.
Cross sections for PI+ PI- and K+ K- production.
Ratio of K+ K- to PI+ PI- production in the region of W from 3.0 to 4.1 GeV, where the ratio is energy independent.
Angular dependence of the normalized differential cross section, $\sigma_0^{-1}{\rm d}\sigma/{\rm d}|\cos\theta^*|$, for the $\pi^+\pi^-$ process. The errors are statistical only.
Measurements were made of the cross section of the reactions π − p → ν ′(958)n, η ′ → 2 γ at momenta at 15, 20, 25, 30 and 40 GeV/c. The experiment was carried out on the IHEP 70 GeV accelerator using the 648 channel hodoscope spectrometer NICE for γ-ray detection. A total of 6000 η′ mesons were recorded. A sharp drop is seen in the differential cross section for t → 0. The dependences of the differential cross sections for the π − p → η ′n and π − p → η n on t are identical. On the basis of the ratio of the cross sections for these reactions at t = 0, i.e. R( η′ n ) t=0 = 0.55 ± 0.06 , the singlet-octet mixing angle for pseudoscalar mesons was determined to be β = −(18.2 ± 1.4)°.
.
AVERAGE RATIO IS 2.76 +- 0.07 PCT.
AVERAGE RATIO IS 0.52 +- 0.02.
None
INCLUDING SYSTEMATIC ERRORS.
STATISTICAL ERRORS ONLY.
STATISTICAL ERRORS ONLY.
The hadronic structure of the photon F2gamma is measured as a function of Bjorken x and of the photon virtuality Q2 using deep-inelastic scattering data taken by the OPAL detector at LEP at e+e- centre-of-mass energies from 183 to 209 GeV. Previous OPAL measurements of the x dependence of F2gamma are extended to an average Q2 of <Q2>=780GeV2 using data in the kinematic range 0.15 < x < 0.98. The Q2 evolution of F2gamma is studied for 12.1 < <Q2> < 780GeV2 using three ranges of x. As predicted by QCD, the data show positive scaling violations in F2gamma for the central x region 0.10-0.60. Several parameterisations of F2gamma are in qualitative agreement with the measurements whereas the quark-parton model prediction fails to describe the data.
F2 and DSIG/DX for the EE sample in the high Q**2 region as a function of X.
Statistical correlations between the bins in the preceding table.
The measured value of F2 and DSIG/DX for the SW data sample in the Q**2 range 9 to 15 GeV**2.
Elements of the spin density matrix for W bosons in e+e- -> W+W- -> qqln events are measured from data recorded by the OPAL detector at LEP. This information is used calculate polarised differential cross-sections and to search for CP-violating effects. Results are presented for W bosons produced in e+e- collisions with centre-of-mass energies between 183 GeV and 209 GeV. The average fraction of W bosons that are longitudinally polarised is found to be (23.9 +- 2.1 +- 1.1)% compared to a Standard Model prediction of (23.9 +- 0.1)%. All results are consistent with CP conservation.
The fraction of longitudinal polarization for leptonically and hadronically decaying W bosons. The average values for all the centre of mass energies and for both lepton and hadron decay combined are also given.
The luminosity weighted average over all the centre of mass energies of the diagonal elements of the RHO++ and RHO-- SDM as a function of the cosine of the angle of the W- boson for the leptonic decay channel.
The luminosity weighted average over all the centre of mass energies of the diagonal element of the RHO00 SDM as a function of the cosine of the angle of the W- boson for both leptonic and hadronic decay channels, and combined.
The process e+ e- -> e+ e- Z/gamma* is studied with the OPAL detector at LEP at a centre of mass energy of sqrt(s) = 189 GeV. The cross-section times the branching ratio of the Z/gamma* decaying into hadrons is measured within Lorentz invariant kinematic limits to be (1.2 +/- 0.3 +/- 0.1) pb for invariant masses of the hadronic system between 5 GeV and 60 GeV and (0.7 +/- 0.2 +/- 0.1) pb for hadronic masses above 60 GeV. The differential cross-sections of the Mandelstam variables s-hat, t-hat, and u-hat are measured and compared with the predictions from the Monte Carlo generators grc4f and PYTHIA. From this, based on a factorisation ansatz, the total and differential cross-sections for the subprocess e gamma -> e Z/gamma* are derived.
Measured values of the cross section times the branching ratio for the (Z0/GAMMA*) decay into hadrons within the restricted kinematic limits.
Differential cross-section dsig_ee/dm_qq.
Differential cross-section dsigma_ee/dsqrt(shat).
Di-jet producion is studied in collisions of quasi-real photons at e+e- centre- of-mass energies sqrt(s)ee from 189 to 209 GeV at LEP. The data were collected with the OPAL detector. Jets are reconstructed using an inclusive k_t clustering algorithm for all cross-section measurements presented. A cone jet algorithm is used in addition to study the different structure of the jets resulting from either of the algorithms. The inclusive di-jet cross-section is measured as a function of the mean transverse energy Etm(jet) of the two leading jets, and as a functiuon of the estimated fraction of the photon momentum carried by the parton entering the hard sub-process, xg, for different regions of Etm (jet). Angular distribution in di-jet events are measured and used to demonstrate the dominance of quark and gluon initiated processes in different regions of phase space. Furthermore the inclusive di-jet cross-section as a function of |eta(jet)| and |delta eta (jet)| is presented where eta(jet) is the jet pseudo-rapidity. Different regions of the xg+ -xg- -space are explored to study and control the influence of an underlying event. The results are compared to next-to-leading order perturbative QCD calculations and to the predictions of the leading order Monte Carlo generator PYTHIA.
The di-jet cross section as a function of the angle between the jet and thedirection of the incoming parton in the centre-of-mass frame for the region whe re both X(C=GAMMA+) and X(C=GAMMA-) are > 0.75.
The di-jet cross section as a function of the angle between the jet and thedirection of the incoming parton in the centre-of-mass frame for the region whe re both X(C=GAMMA+) and X(C=GAMMA-) are < 0.75.
The di-jet cross section as a function of the mean transverse energy of thedi-jet system for the full X(C=GAMMA+) and X(C=GAMMA-) region.
Differential cross sections for the reaction $\gamma p \to n \pi^+$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Where available, the results obtained here compare well with previously published results for the reaction. Agreement with the SAID and MAID analyses is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been made up to 2.7 GeV. Resonance couplings have been extracted and compared to previous determinations. With the addition of these cross sections to the world data set, significant changes have occurred in the high-energy behavior of the SAID cross-section predictions and amplitudes.
Differential cross sections for incident photon energies 0.725, 0.775, 0.825and 0.875 GeV.
Differential cross sections for incident photon energies 0.925, 0.975, 1.025and 1.075 GeV.
Differential cross sections for incident photon energies 1.125, 1.175, 1.225and 1.275 GeV.
We have observed inclusive production of D0 and D+ mesons, and their charge conjugates, in e+e− annihilation at 29 GeV on the basis of a data sample of 106 pb−1. These signals correspond to R values of R(D0+D―0)=1.8±0.5 and R(D++D−)=1.2±0.4. Taking the D+ and D0 data together, we measure a charge asymmetry of A=−0.08±0.12 for charmed quarks. A comparison of R(D+D―) with R(D*+D―*) obtained via the process D*+→D0π+ gives a DD* ratio of 1.0−0.2+0.3, indicating that direct D* production dominates over direct D production.
No description provided.
EXTRAPOLATED TO ALL Z.
No description provided.
The exclusive reactions $\gamma p \to K^{*0} \Sigma^+(1189)$ and $\gamma p \to K^{0} \pi^{0}\Sigma^+(1189)$, leading to the p 4$\pi^{0}$ final state, have been measured with a tagged photon beam for incident energies from threshold up to 2.5 GeV. The experiment has been performed at the tagged photon facility of the ELSA accelerator (Bonn). The Crystal Barrel and TAPS detectors were combined to a photon detector system of almost 4$\pi$ geometrical acceptance. Differential and total cross sections are reported. At energies close to the threshold, a flat angular distribution has been observed for the reaction $\gamma p\to K^{0} \pi^{0}\Sigma^+$ suggesting dominant s-channel production. $\Sigma^*(1385)$ and higher lying hyperon states have been observed. An enhancement in the forward direction in the angular distributions of the reaction $\gamma p \to K^{*0}\Sigma^+$ indicates a $t$-channel exchange contribution to the reaction mechanism. The experimental data are in reasonable agreement with recent theoretical predictions.
Differential cross section D(SIG)/DCOS(THETA(SIG+)) for the GAMMA P --> K0 PI0 SIGMA+ reaction for beam energies 1500-1700 and 1700-1850 MeV.
Differential cross section D(SIG)/DCOS(THETA(SIG+)) for the GAMMA P --> K0 PI0 SIGMA+ reaction for beam energies 1850-2000 and 2000-2150 MeV.
Differential cross section D(SIG)/DCOS(THETA(SIG+)) for the GAMMA P --> K0 PI0 SIGMA+ reaction for beam energies 2150-2300 and 2300-2500 MeV.
The total cross sections for the elastic electroproduction of $\rh0$ and $J/\Psi$ mesons for $Q~2$ $>$ 8 GeV$~2$ and $\langle W \rangle \simeq 90$ GeV/c$~2$ are measured at HERA with the H1 detector. The measurements are for an integrated electron$-$proton luminosity of $\simeq$3pb$~{-1}$. The dependences of the total virtual photon$-$proton ($\gamma~* p$) cross sections on $Q~2$, $W$ and the momentum transfer squared to the proton ($t$), and, for the $\rho$, the dependence on the polar decay angle ($\cos \theta~*$), are presented. The $J/\Psi$ : $\rh0$ cross section ratio is determined. The results are discussed in the light of theoretical models and of the interplay of hard and soft physics processes.
Overall EP cross section for M(PI+PI-) < 1.5 GEV.
Overall EP cross section, taking into account the J/PSI --> LEPTON+ LEPTON - branching fraction 0.12.
Integrated EP cross section.
The electroweak production asymmetry and the decay fragmentation function for e + e − → c c have been measured at s = 29 GeV using charged D ∗ production over the full kinematic range. The data were taken at PEP using the High Resolution Spectrometer. The measured asymmetry is −0.12 ± 0.08. The total production cross section in units of the point cross section corrected for initial state radiation is R D ∗ = 2.7 ± 0.9 .
ASSUMES SIG(D*+) = SIG(D*0). (EXPT. MEASURES D*+ PRODUCTION ONLY). R VALUE CORRECTED FOR INITIAL STATE RADIATION.
No description provided.
The reactions gamma p --> K+ Lambda and gamma p --> K+ Sigma0 were measured in the energy range from threshold up to a photon energy of 2.6 GeV. The data were taken with the SAPHIR detector at the electron stretcher facility, ELSA. Results on cross sections and hyperon polarizations are presented as a function of kaon production angle and photon energy. The total cross section for Lambda production rises steeply with energy close to threshold, whereas the Sigma0 cross section rises slowly to a maximum at about E_gamma = 1.45 GeV. Cross sections together with their angular decompositions into Legendre polynomials suggest contributions from resonance production for both reactions. In general, the induced polarization of Lambda has negative values in the kaon forward direction and positive values in the backward direction. The magnitude varies with energy. The polarization of Sigma0 follows a similar angular and energy dependence as that of Lambda, but with opposite sign.
Differential cross sections for the reaction GAMMA P --> K+ LAMBDA in the energy region 0.9 to 1.0 GeV.
Differential cross sections for the reaction GAMMA P --> K+ LAMBDA in the energy region 1.0 to 1.2 GeV.
Differential cross sections for the reaction GAMMA P --> K+ LAMBDA in the energy region 1.2 to 1.4 GeV.
None
No description provided.
A new measurement of αs is obtained from the distributions in thrust, heavy jet mass, energy-energy correlation and two recently introduced jet broadening variables following a method proposed by Cata
Thrust distribution corrected for detector acceptance and initial state photon radiation.
Heavy jet mass (RHO) distribution (THRUST definition) corrected for detect or acceptance and initial state photon radiation.
Heavy jet mass (RHOM) distribution (MASS definition) corrected for detectoracceptance and initial state photon radiation.
Quasi-free photoproduction of eta-mesons off nucleons bound in the deuteron has been measured with the CBELSA/TAPS detector for incident photon energies up to 2.5 GeV at the Bonn ELSA accelerator. The eta-mesons have been detected in coincidence with recoil protons and recoil neutrons, which allows a detailed comparison of the quasi-free n(gamma,eta)n and p(gamma,eta)p reactions. The excitation function for eta-production off the neutron shows a pronounced bump-like structure at W=1.68 GeV (E_g ~ 1 GeV), which is absent for the proton.
Measured value of the quasi-free eta cross section off protons and neutrons as a function of incident photon energy.
Ratio of the measured quasi-free neutron to proton cross sections as a function of incident photon energy.
Measured angular distribution for an incident photon energy of 0.700 GeV.
As a part of the study of the inclusive production of electron pairs in pp collisions at the CERN Intersecting Storage Rings (ISR), a search has been performed for additional photons accompanying J/ψ particles. The results suggest that (43±21)% of the J/ψ's are produced via the photonic decay of one of the χ(3.5) states.
The cross section times branching ratio.
Photoproduction of $\eta$ mesons off $^{12}$C, $^{40}$Ca, $^{93}$Nb, and $^{nat}$Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2 GeV. The experiment was performed at the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties of the S$_{11}$(1535) nucleon resonance and the study of the absorption properties of nuclear matter for $\eta$ mesons. Careful consideration was given to contributions from $\eta\pi$ final states and secondary production mechanisms of $\eta$-mesons e.g. from inelastic $\pi N$ reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross section $\sigma_{N\eta}$ for $\eta$ mesons is constant over a wide range of the $\eta$ momentum. The comparison of the excitation functions to data off the deuteron and to calculations in the framework of a BUU-model show no unexplained in-medium modifications of the S$_{11}$(1535).
Inclusive energy distribution for incident photon energy 0.650 to 0.835 GeV.
Inclusive energy distribution for incident photon energy 0.835 to 1.050 GeV.
Inclusive energy distribution for incident photon energy 1.050 to 1.550 GeV.
A high precision study of the process gamma gamma -> p p-bar has been performed using a data sample of 89/fb collected with the Belle detector at the KEKB e+e- collider. The cross section of p p-bar production has been measured at two-photon center-of-mass (c.m.) energies between 2.025 and 4.0 GeV and in the c.m. angular range of |cos(theta^*)|<0.6. Production of gamma gamma -> eta_c -> p p-bar is observed and the product of the two-photon width of the eta_c and its branching ratio to p p-bar is determined.
Measured cross section for GAMMA GAMMA --> PBAR P in the angular region ABS(COS(THETA)) < 0.6.
Measured differential cross sections versus COS(THETA) for the W ranges 2.075 to 2.5, 2.5 to 3.0 and 3.0 to 4.0 GeV.
Measured differential cross sections versus COS(THETA) for the W ranges 2.075 to 2.1, 2.1 to 2.2 and 2.2 to 2.3 GeV.
The differential cross-section for the process p(e,e'p)eta has been measured at Q2 ~ 5.7 and 7.0 (GeV/c)2 for centre-of-mass energies from threshold to 1.8 GeV, encompassing the S11(1535) resonance, which dominates the channel. This is the highest momentum transfer measurement of this exclusive process to date. The helicity-conserving transition amplitude A_1/2, for the production of the S11(1535) resonance, is extracted from the data. This quantity appears to begin scaling as 1/Q3, a predicted signal of the dominance of perturbative QCD, at Q2 ~ 5 (GeV/c)2.
Total cross section for the lower Q**2 data as a function of W. The errors are statistics and systematic added in quadrature.
Total cross section for the higher Q**2 data as a function of W. The errors are statistics and systematic added in quadrature.
Lower Q**2 extracted differential cross section at W = 1.500 GeV and cos(theta(eta) = -0.917, -0.750 and -0.583.
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