6,663 research outputs found

    Extraction of R = sigma_L/sigma_T from CCFR nu_mu-Fe and nubar_mu-Fe differential cross sections

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    We report on the extraction of R=sigma_L/sigma_T from CCFR nu_mu-Fe and nubar_mu-Fe differential cross sections. The CCFR differential cross sections do not show the deviations from the QCD expectations that are seen in the CDHSW data at very low and very high x. R as measured in nu_mu scattering is in agreement with R as measured in muon and electron scattering. All data on R for Q^2 > 1 GeV^2 are in agreement with a NNLO QCD calculation which includes target mass effects. We report on the first measurements of R in the low x and Q^2 < 1 GeV^2 region (where an anomalous large rise in R for nuclear targets has been observed by the HERMES collaboration).Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

    New Measurements of Nucleon Structure Functions from CCFR/NuTeV

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    We report on the extraction of the structure functions F_2 and Delta xF_3 = xF_3nu-xF_3nub from CCFR neutrino-Fe and antineutrino-Fe differential cross sections. The extraction is performed in a physics model independent (PMI) way. This first measurement for Delta xF_3, which is useful in testing models of heavy charm production, is higher than current theoretical predictions. Within 5% the F_2 (PMI) values measured in neutrino and muon scattering are in agreement with the predictions of Next-to-Leading-Order PDFs (using massive charm production schemes), thus resolving the long-standing discrepancy between the two measurements.Comment: 3 pages, Presented by Arie Bodek at DPF2000 Conference, Columbus, Ohio, Aug. 200

    The scaling relation of early-type galaxies in clusters. II: Spectroscopic data for galaxies in eight nearby clusters

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    AIMS: We present in this work low and intermediate resolution spectroscopic data collected for 152 early type galaxies in 8 nearby clusters with z ≤\leq 0.10. METHODS: We use low resolution data to produce the redshift and the K-correction for every individual galaxy, as well as to give their overall spectral energy distribution, and some spectral indicators, including the 4000\AA break, the Mg2_2 strength, and the NaD equivalent width.We have also obtained higher resolution data for early type galaxies in three of the clusters, to determine their central velocity dispersion. RESULTS: The effect of the resolution on the measured parameters is discussed. CONCLUSIONS: New accurate systemic redshift and velocity dispersion is presented for four of the surveyed clusters, A98, A3125, A3330, and DC2103-39. We have found that the K-correction values for E/S0 bright galaxies in a given nearby clusters are very similar. We also find that the distribution of the line indicators significantly differ from cluster to cluster.Comment: 16 pages, 9 figures, Accepted in A&

    A High Statistics Search for Electron-Neutrino --> Tau-Neutrino Oscillations

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    We present new limits on nu_e to nu_tau and nu_e to nu_sterile oscillations by searching for electron neutrino dissappearance in the high-energy wide-band CCFR neutrino beam. Sensitivity to nu_tau appearance comes from tau decay modes in which a large fraction of the energy deposited is electromagnetic. The beam is composed primarily of muon neutrinos but this analysis uses the 2.3% electron neutrino component of the beam. Electron neutrino energies range from 30 to 600 GeV and flight lengths vary from 0.9 to 1.4 km. This limit improves the sensitivity of existing limits and obtains a lowest 90% confidence upper limit in sin**2(2*alpha) of 9.9 x 10**(-2) at delta-m**2 of 125 eV**2.Comment: submitted to Phys. Rev. D. Rapid Com

    Nuclear Structure Functions in the Large x Large Q^2 Kinematic Region in Neutrino Deep Inelastic Scattering

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    Data from the CCFR E770 Neutrino Deep Inelastic Scattering (DIS) experiment at Fermilab contain events with large Bjorken x (x>0.7) and high momentum transfer (Q^2>50 (GeV/c)^2). A comparison of the data with a model based on no nuclear effects at large x, shows a significant excess of events in the data. Addition of Fermi gas motion of the nucleons in the nucleus to the model does not explain the excess. Adding a higher momentum tail due to the formation of ``quasi-deuterons'' makes some improvement. An exponentially falling F_2 \propto e^-s(x-x_0) at large x, predicted by ``multi-quark clusters'' and ``few-nucleon correlations'', can describe the data. A value of s=8.3 \pm 0.7(stat.)\pm 0.7(sys.) yields the best agreement with the data.Comment: 4 pages, 4 figures, 1 table. Sibmitted to PR

    A measurement of alphas(Q2)alpha_s(Q^2) from the Gross-Llewellyn Smith Sum Rule

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    We extract a set of values for the Gross-Llewellyn Smith sum rule at different values of 4-momentum transfer squared (Q2Q^{2}), by combining revised CCFR neutrino data with data from other neutrino deep-inelastic scattering experiments for 1<Q2<15GeV2/c21 < Q^2 < 15 GeV^2/c^2. A comparison with the order αs3\alpha^{3}_{s} theoretical predictions yields a determination of αs\alpha_{s} at the scale of the Z-boson mass of 0.114±.012.0090.114 \pm^{.009}_{.012}. This measurement provides a new and useful test of perturbative QCD at low Q2Q^2, because of the low uncertainties in the higher order calculations.Comment: 4 pages, 4 figure

    Search for the Lepton Number Violating Process nu_mu-bar e^- -> mu^- nu_e-bar

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    The NuTeV experiment at Fermilab has used a sign-selected neutrino beam to perform a search for the lepton number violating process nu_mu-bar e^- -> mu^- nu_e-bar, and to measure the cross-section of the Standard Model inverse muon decay process nu_mu e^- -> mu^- nu_e. NuTeV measures the inverse muon decay asymptotic cross-section sigma/E to be 13.8 +/- 1.2 +/- 1.4 x 10^-42 cm^2/GeV. The experiment also observes no evidence for lepton number violation and places one of the most restrictive limits on the LNV/IMD cross-section ratio at < 1.7% at 90% C.L. for V-A couplings and < 0.6% for scalar couplings.Comment: 4 pages, 4 figures, 2 tables. Submitted to Physics Review Letter

    Detection of Supernova Neutrinos by Neutrino-Proton Elastic Scattering

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    We propose that neutrino-proton elastic scattering, ν+p→ν+p\nu + p \to \nu + p, can be used for the detection of supernova neutrinos in scintillator detectors. Though the proton recoil kinetic energy spectrum is soft, with Tp≃2Eν2/MpT_p \simeq 2 E_\nu^2/M_p, and the scintillation light output from slow, heavily ionizing protons is quenched, the yield above a realistic threshold is nearly as large as that from νˉe+p→e++n\bar{\nu}_e + p \to e^+ + n. In addition, the measured proton spectrum is related to the incident neutrino spectrum, which solves a long-standing problem of how to separately measure the total energy and temperature of νμ\nu_\mu, ντ\nu_\tau, νˉμ\bar{\nu}_\mu, and νˉτ\bar{\nu}_\tau. The ability to detect this signal would give detectors like KamLAND and Borexino a crucial and unique role in the quest to detect supernova neutrinos.Comment: 10 pages, 9 figures, revtex

    A Precise Measurement of the Weak Mixing Angle in Neutrino-Nucleon Scattering

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    We report a precise measurement of the weak mixing angle from the ratio of neutral current to charged current inclusive cross-sections in deep-inelastic neutrino-nucleon scattering. The data were gathered at the CCFR neutrino detector in the Fermilab quadrupole-triplet neutrino beam, with neutrino energies up to 600 GeV. Using the on-shell definition, sin2θW≡1−MW2MZ2{\rm sin ^2\theta_W} \equiv 1 - \frac{{\rm M_W} ^2}{{\rm M_Z} ^2}, we obtain sin2θW=0.2218±0.0025(stat.)±0.0036(exp. syst.)±0.0040(model){\rm sin ^2\theta_W} = 0.2218 \pm 0.0025 ({\rm stat.}) \pm 0.0036 ({\rm exp.\: syst.}) \pm 0.0040 ({\rm model}).Comment: 10 pages, Nevis Preprint #1498 (Submitted to Phys. Rev. Lett.
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