None
No description provided.
No description provided.
No description provided.
The reaction $~{12}{\rm C}(\nu_\mu,\mu~-) {\rm X}$ has been measured near threshold using a $\pi ~+$ decay-in-flight $\nu_\mu$ beam from the Los Alamos Meson Physics Facility and a massive liquid scintillator neutrino detector (LSND). In the energy region $123.7 < {\rm E}_\nu < 280$ MeV, the measured spectral shape is consistent with that expected from the Fermi Gas Model. However, the measured flux--averaged inclusive cross section ($(8.3 \pm 0.7 {\rm stat.} \pm 1.6 {\rm syst.}) \times 10~{-40} {\rm cm}~2$) is more than a factor of 2 lower than that predicted by the Fermi Gas Model and by a recent random phase approximation calculation.
No description provided.
Measurements have been made of pi+ absorption on He3 at T_pi+ = 118, 162, and 239 MeV using the Large Acceptance Detector System (LADS). The nearly 4pi solid angle coverage of this detector minimizes uncertainties associated with extrapolations over unmeasured regions of phase space. The total absorption cross section is reported. In addition, the total cross section is divided into components in which only two or all three nucleons play a significant role in the process. These are the first direct measurements of the total and three nucleon absorption cross sections.
ABSORPTION CROSS SECTION.
ABSORPTION CROSS SECTION.
In the very heavy collision system Au197+197Au the K+ production process was studied as a function of impact parameter at 1 GeV/nucleon, a beam energy well below the free N-N threshold. The K+ multiplicity increases more than linearly with the number of participant nucleons and the K+/π+ ratio rises significantly when going from peripheral to central collisions. The measured K+ double differential cross section is enhanced by a factor of 6 compared to microscopic transport calculations if secondary processes (ΔN→KΛN and ΔΔ→KΛN) are ignored.
No description provided.
The total K+ cross section is determined by extrapolating and integrating the double differential cross section d2(sig)/d(p)/d(omega) over momentum and solid angle.
The inclusive cross sections, measured up to large values of effective mass (≡q22ν), are well fitted by dσd3p=Bxexp(−αxp22mx). Values of Bx and αx are given for Be, C, Cu, and Ta at the incident proton energy of 600 MeV and for Ag, Ta, and Pt at 800 MeV. Extremely large dp and tp ratios and large A and q2 dependences of the relative cross sections are observed.
D3(SIG)/D3(P) is fitted by the equation: CONST*exp(-SLOPE*P**2/(2*M)). CONST is presented per nucleon.
D3(SIG)/D3(P) is fitted by the equation: CONST*exp(-SLOPE*P**2/(2*M)). CONST is presented per nucleon.
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.
A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current $e^{\pm}p$ scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb$^{-1}$ and span six orders of magnitude in negative four-momentum-transfer squared, $Q^2$, and Bjorken $x$. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisation, HERAPDF2.0AG, and using fixed-flavour-number schemes, HERAPDF2.0FF, are presented. The analysis was extended by including HERA data on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jet-production cross sections made a simultaneous determination of these parton distributions and the strong coupling constant possible, resulting in $\alpha_s(M_Z)=0.1183 \pm 0.0009 {\rm(exp)} \pm 0.0005{\rm (model/parameterisation)} \pm 0.0012{\rm (hadronisation)} ^{+0.0037}_{-0.0030}{\rm (scale)}$. An extraction of $xF_3^{\gamma Z}$ and results on electroweak unification and scaling violations are also presented.
HERA combined reduced cross sections $\sigma_{r,\rm NC}^{+}$ for NC $e^{+}p$ scattering at $\sqrt{s} = 318$ GeV; $\delta_{\rm stat}$, $\delta_{\rm uncor}$ and $\delta_{\rm cor}$ represent the statistical, uncorrelated systematic and correlated systematic uncertainties, respectively; $\delta_{\rm rel}$, $\delta_{\gamma p}$, $\delta_{\rm had}$ and $\delta_{1}$ to $\delta_{4}$ are the correlated sources of uncertainties arising from the combination procedure. The uncertainties are quoted in percent relative to $\sigma_{r,\rm NC}^{+}$.
HERA combined reduced cross sections $\sigma_{r,\rm NC}^{+}$ for NC $e^{+}p$ scattering at $\sqrt{s} = 300$ GeV; $\delta_{\rm stat}$, $\delta_{\rm uncor}$ and $\delta_{\rm cor}$ represent the statistical, uncorrelated systematic and correlated systematic uncertainties, respectively; $\delta_{\rm rel}$, $\delta_{\gamma p}$, $\delta_{\rm had}$ and $\delta_{1}$ to $\delta_{4}$ are the correlated sources of uncertainties arising from the combination procedure. The uncertainties are quoted in percent relative to $\sigma_{r,\rm NC}^{+}$.
HERA combined reduced cross sections $\sigma_{r,\rm NC}^{+}$ for NC $e^{+}p$ scattering at $\sqrt{s} = 251$ GeV; $\delta_{\rm stat}$, $\delta_{\rm uncor}$ and $\delta_{\rm cor}$ represent the statistical, uncorrelated systematic and correlated systematic uncertainties, respectively; $\delta_{\rm rel}$, $\delta_{\gamma p}$, $\delta_{\rm had}$ and $\delta_{1}$ to $\delta_{4}$ are the correlated sources of uncertainties arising from the combination procedure. The uncertainties are quoted in percent relative to $\sigma_{r,\rm NC}^{+}$.
We have measured the analyzing power A y in n-d elastic scattering at 67.0 MeV. The experiment was based on the detection of recoil deuterons, allowing for a precise measurement of the backward angular range. The results are in good agreement with recent three-nucleon calculations which are based on the Paris and Bonn NN potentials.
No description provided.
The reaction e + p → e ′+ N ∗ was studied for four momentum transfers up to 2.34 (GeV/ c ) 2 in the region of the 1236 MeV isobar. An analysis of the data in terms of the cross sections σ T and σ L for the absorption of transverse and longitudinal photons is given for invariant masses of the final pion nucleon system W =1.220 GeV and W =1.350 GeV.
Total errors are presented.
Total errors are presented.
Total errors are presented.
We present high precision measurements of elliptic flow near midrapidity ($|y|<1.0$) for multi-strange hadrons and $\phi$ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy $\sqrt{s_{NN}}=$ 200 GeV. We observe that the transverse momentum dependence of $\phi$ and $\Omega$ $v_{2}$ is similar to that of $\pi$ and $p$, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0-30$\%$ and 30-80$\%$ collision centrality. There is an indication of the breakdown of previously observed mass ordering between $\phi$ and proton $v_{2}$ at low transverse momentum in the 0-30$\%$ centrality range, possibly indicating late hadronic interactions affecting the proton $v_{2}$.
No description provided.
No description provided.
No description provided.