The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies ${\sim}0.8$ GeV. The differential measurements are presented as a function of muon and pion kinematics, in the restricted phase-space defined by $p_{\pi^+}>200$MeV/c, $p_{\mu^-}>200$MeV/c, $\cos \theta_{\pi^+}>0.3$ and $\cos \theta_{\mu^-}>0.3$. The total flux integrated $\nu_\mu$ charged current single positive pion production cross section on water in the restricted phase-space is measured to be $\langle\sigma\rangle_\phi=4.25\pm0.48 (\mathrm{stat})\pm1.56 (\mathrm{syst})\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$. The total cross section is consistent with the NEUT prediction ($5.03\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$) and 2$\sigma$ lower than the GENIE prediction ($7.68\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but over-estimates the overall cross section normalization.
Total $\nu_\mu$ CC1$\pi^+$ cross section on water in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$. The T2K data point is placed at the $\nu_\mu$ flux mean energy.
Unfolded $\nu_\mu$ CC1$\pi^+$ differential cross section as a function of $p_\pi$ in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$.
Unfolded $\nu_\mu$ CC1$\pi^+$ differential cross section as a function of $\cos\theta_\pi$ in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$.
The ATLAS experiment at the LHC has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at sqrt(s) = 7 TeV. The full data set collected in 2011, corresponding to an integrated luminosity of 4.9 fb-1, is used. The amount of background, from hadronic jets and isolated electrons, is estimated with data-driven techniques and subtracted. The total cross section, for two isolated photons with transverse energies above 25 GeV and 22 GeV respectively, in the acceptance of the electromagnetic calorimeter (|eta|<1.37 and 1.52<|eta|<2.37) and with an angular separation Delta R>0.4, is 44.0 (+3.2) (-4.2) pb. The differential cross sections as a function of the di-photon invariant mass, transverse momentum, azimuthal separation, and cosine of the polar angle of the largest transverse energy photon in the Collins--Soper di-photon rest frame are also measured. The results are compared to the prediction of leading-order parton-shower and next-to-leading-order and next-to-next-to-leading-order parton-level generators.
Experimental cross-section values per bin in PB*GEV**-1 for M(2GAMMA).
Experimental cross-section values per bin in PB*GEV**-1 for PT(2GAMMA).
Experimental cross-section values per bin in PB*RAD**-1 for DELTA(PHI(2GAMMA)).
A first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based on a sample of pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 inverse-femtobarns. A high-purity sample of t-channel single top quark events with an isolated muon is selected. Signal and background components are estimated using a fit to data. A differential cross section measurement, corrected for detector effects, of an angular observable sensitive to the top quark polarisation is performed. The differential distribution is used to extract a top quark spin asymmetry of 0.26 +/- 0.03 (stat) +/- 0.10 (syst), which is compatible with a p-value of 4.6% with the standard model prediction of 0.44.
The normalized differential cross section as a function of unfolded $\cos\theta_{\mu}^{*}$ for top quark.
The normalized differential cross section as a function of unfolded $\cos\theta_{\mu}^{*}$ for top antiquark.
The normalized differential cross section as a function of unfolded $\cos\theta_{\mu}^{*}$ for top quark and antiquark.
The invariant cross section of the reaction of deuteron stripping on carbon target has been measured at a deuteron momentum of 8.9 GeV/c. The cross section is obtained at a zero detection angle of the stripping proton: E/p2xd2σ/dpdΩ=(281+-9)xbxGeV/srx(GeV/c)3. This value is consistent with the one calculated in the framework of the Bertocci-Treleani model of deuteron fragmentation. When the method of Nissen-Meyer is used for orthogonalization of the wave functions of primary deuteron and the (np) system, resulting from its disintegration, a similar calculation gives the result, which is 1.4 times larger than the measured value. Distribution in the cosine of angle of proton yield at the fixed proton momentum p turned out to be near to isotropy one and distribution in p at the fixed cos theta has the maximum at p=50 MeV/c
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ω photoproduction off hydrogen and deuterium has been studied with the tagged photon beam of the ELSA accelerator in Bonn for photon energies up to 2.0 GeV. The ω meson has been identified via the ω → π$^{0}$ γ → γγγ decay mode, using the combined setup of the Crystal Barrel/TAPS detector systems. Both inclusive and exclusive analyses have been carried out. Differential and total cross-sections have been derived for ω mesons produced off free protons and off protons and neutrons bound in deuterium. The cross-section for the production off the bound neutron is found to be a factor of ≈ 1.3 larger than the one off the bound proton in the incident beam energy region 1.2 GeV < E$_{γ}$ < 1.6 GeV. For higher incident beam energies this factor goes down to ≈ 1.1 at 2.0 GeV. The cross-sections of this work have been used as normalization for transparency ratio measurements.
Differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.125-1.150 GeV.
Differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.150-1.175 GeV.
Differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.175-1.200 GeV.
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PROTONS MOMENTA LIE IN LAB BACKWARD HEMISPHERE.
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THESE ARE CORRECTED DATA FROM YF 40, 34. PROPER TABLES IN YF 40, 34 MUST. BE REPLACED BY THE GOOD ONES.
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.
Cross-sections for the photoproduction of events containing four high-$E_{\rm T}$ jets have been measured with the ZEUS detector using an integrated luminosity of 38.7 pb$^{-1}$. At low invariant mass of the four-jet system, $m_{\rm 4J}$, the observed event distributions are sensitive to the underlying event model. The inclusion of multi-parton interactions in Monte Carlo simulations lead to a significantly better description of the data. For $m_{\rm 4J} > 50 $ GeV the data is adequately described by models with no simulation of an underlying event, suggesting that this is a kinematic region suitable for comparison with perturbative QCD calculations.
The measured normalised costheta3 distributions.
The measured normalised psi3 distributions.
The measured normalised X3 distributions.
The diffractive photoproduction of rho mesons, e p \to e rho Y, with large momentum transfer squared at the proton vertex, |t|, is studied with the H1 detector at HERA using an integrated luminosity of 20.1 pb^{-1}. The photon-proton centre of mass energy spans the range 75 < W < 95 GeV, the photon virtuality is restricted to Q^2 < 0.01 GeV^2 and the mass M_Y of the proton remnant is below 5 GeV. The t dependence of the cross section is measured for the range 1.5 < |t| < 10.0 GeV^2 and is well described by a power law, dsigma/ d|t| \propto |t|^{-n}. The spin density matrix elements, which provide information on the helicity structure of the interaction, are extracted using measurements of angular distributions of the rho decay products. The data indicate a violation of s-channel helicity conservation, with contributions from both single and double helicity-flip being observed. The results are compared to the predictions of perturbative QCD models.
The normalized differential cross section as a function of T.
Normalised decay angular distribution w.r.t. the polar angle THETA.
Normalised decay angular distribution w.r.t. the polar angle THETA.
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