Highly inelastic processes in hadron-nucleus reactions at several GeV have been studied by measuring multi-particle emission in the target-rapidity region. Events with no leading particle(s) but with high multiplicities were observed up to 4 GeV. Proton spectra from such events were well reproduced with a single-moving-source model, which implied possible formation of a local source. The number of nucleons involved in the source was estimated to be (3–5)A 1 3 from the source velocity and the multiplicity of emitted protons. In those processes the incident energy flux seemed to be deposited totally or mostly (>62;75%) in the target nucleus to form the local source. The cross sections for the process were about 30% of the geometrical cross sections, with little dependence on incident energies up to 4 GeV and no dependence on projectiles (pions or protons). The E 0 parameter in the invariant-cross-section formula E d 3 σ /d p 3 = A exp (− E / E 0 ) for protons from the source increases with incident energy from 1 to 4 GeV/ c , but seems to saturate above 10 GeV at a value E 0 = 60–70 MeV. Three components in the emitted nucleon spectra were observed which would correspond to three stages of the reaction process: primary, pre-equilibrium and equilibrium.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
The proton polarization in deuteron photodisintegration has been measured at photon energies between 400 and 650 MeV at c.m. angles between 45° and 135°. To explain the polarization and differential cross-section data consistently, we have introduced dibaryon resonances and performed a partial-wave analysis at photon energies between 350 and 700 MeV. It has been shown that the existence of at least two dibaryon resonances is required in this energy range: one at ∼2380MeV with I ( J P ) = 0(3 + ) or 0(1 + ), and the other at ∼2260 MeV with I ( J P ) = 1(3 − ) or 1(2 − ).
No description provided.
The recoil proton polarization for γ n → π − p was measured around the third resonance region. Both momentum vectors of the proton and the pion were determined by the magnetic spectrometers. The proton polarization was measured by means of proton-carbon scattering in the polarization analyzer located behind the proton spectrometer. Below 900 MeV incident photon energy, our data are consistent with the other existing experimental data ( θ π ∗ = 90° ) and the predictions of partial-wave analyses. Above 1000 MeV, however, a large discrepancy was observed between our data and the predictions of the partial-wave analyses. The discrepancy stands out as the pion c.m. angle increases. A new partial-wave analysis was made for γ n → π − p including our polarization data, and the accuracy of the experimentally determined electromagnetic coupling constant of the third resonances were greatly improved. In particular, a finite amount of the helicity 3 2 amplitude for the γ n → F 15 (1688) resonance was obtained against the predictions of the quark models, by Copley, Karl and Obryk and by Feynman, Kislinger and Ravendal but in agreement with the relativistic quark models of Sugimoto and Toya, and Kubota and Ohta.
No description provided.
We have made the first systematic precision measurement of the deuteron-deuteron total cross sections at 12 incident momenta in the range of 1.5–4.0 GeV/c on a proton synchrotron. The data were obtained by means of the transmission method covering the momentum transfer squared range of 0.001 to 0.009 (GeV/c)2 at each momentum. Our data show no anomalous structure in the excitation function and are in good agreement with Glauber model calculations including the effect of the Fermi motion of the nucleons in the deuteron except at 1.5 GeV/c, where the datum is lower than the calculated value.
Errors contain both statistics and systematics.
The proton polarization in the γ d → pn reaction has been measured at a c.m. angle of 90° and photon energies between 350 and 700 MeV, using a carbon polarimeter. The magnitude of the polarization shows a sharp energy dependence with a peak of about −80% at around 500–550 MeV. This feature cannot be explained by conventional models and seems to indicate a new mechanism in the dibaryon system.
AROUND THETA OF 90 DEG.
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ERRORS INCLUDE BY QUADRATIC ADDITION THE 5 PCT UNCERTAINTY IN THE CARBON ANALYSING POWER.
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The Dalitz plot parameters G, H, and K are used in the standard parameterization of the matrix element squared (see PDG): M**2 = 1 + G*X + H*X**2 + K*Y**2,where X = (s3-s0)/m(PI)**2 and Y = (s1-s2)/m(PI)**2, s1 = (pK - pPI0)**2, s2 = (pK - pPI0)**2, s3 = (pK - pPI+)**2, s0 = (s1+s2+s3)/3.
Proton polarization in γd→pn has been measured at c.m. angle around 90° and photon energies from 325 to 725 MeV. The polarization increases sharply with the photon energy, reaching a high maximum of (-80±8)% around 500-550 MeV. Such a high polarization with a sharp energy dependence seems to indicate a new effect in the dibaryon system.
No description provided.
This paper presents cross sections for the production of a W boson in association with jets, measured in proton--proton collisions at $\sqrt{s}=7$ TeV with the ATLAS experiment at the Large Hadron Collider. With an integrated luminosity of $4.6 fb^{-1}$, this data set allows for an exploration of a large kinematic range, including jet production up to a transverse momentum of 1 TeV and multiplicities up to seven associated jets. The production cross sections for W bosons are measured in both the electron and muon decay channels. Differential cross sections for many observables are also presented including measurements of the jet observables such as the rapidities and the transverse momenta as well as measurements of event observables such as the scalar sums of the transverse momenta of the jets. The measurements are compared to numerous QCD predictions including next-to-leading-order perturbative calculations, resummation calculations and Monte Carlo generators.
Distribution of inclusive jet multiplicity.
Breakdown of systematic uncertainties in percent in inclusive jet multiplicity in the electron channel.Uncertainties have been symmetrised and the sign denotes the sign of the original up-variation.
Breakdown of systematic uncertainties in percent in inclusive jet multiplicity in the muon channel.Uncertainties have been symmetrised and the sign denotes the sign of the original up-variation.
This paper presents a measurement of the $W$ boson production cross section and the $W^{+}/W^{-}$ cross-section ratio, both in association with jets, in proton--proton collisions at $\sqrt{s}=8$ TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum using data corresponding to an integrated luminosity of 20.2 fb$^{-1}$. Differential cross sections for events with one or two jets are presented for a range of observables, including jet transverse momenta and rapidities, the scalar sum of transverse momenta of the visible particles and the missing transverse momentum in the event, and the transverse momentum of the $W$ boson. For a subset of the observables, the differential cross sections of positively and negatively charged $W$ bosons are measured separately. In the cross-section ratio of $W^{+}/W^{-}$ the dominant systematic uncertainties cancel out, improving the measurement precision by up to a factor of nine. The observables and ratios selected for this paper provide valuable input for the up quark, down quark, and gluon parton distribution functions of the proton.
Cross section for the production of W bosons for different inclusive jet multiplicities.
Statistical correlation between bins in data for the cross section for the production of W bosons for different inclusive jet multiplicities.
Differential cross sections for the production of W<sup>+</sup> bosons, W<sup>-</sup> bosons and the W<sup>+</sup>/W<sup>-</sup> cross section ratio as a function of the inclusive jet multiplicity.
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