1,716 research outputs found
A Precise Determination of Electroweak Parameters in Neutrino-Nucleon Scattering
The NuTeV collaboration has extracted sin^2theta_W from the ratios of neutral
current to charged current neutrino and anti-neutrino cross-sections. Our
value, sin^2theta_W(on-shell)=0.2277+/-0.0013(stat)+/-0.0009(syst), is three
standard deviations above the standard model prediction. We also present a
model independent analysis of the same data.Comment: ReVTeX, 5 pp, 1fig; v2. revised SM prediction; v3. more sig. digits
in Eqns 6-7, fix error in Eqn
Extraction of R = sigma_L/sigma_T from CCFR nu_mu-Fe and nubar_mu-Fe differential cross sections
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
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
A Search for Muon-neutrino to Electron-neutrino and Muon-antineutrino to Electron-antineutrino Oscillations at NuTeV
Limits on and oscillations
are extracted using the NuTeV detector with sign-selected and
\nub_\mu beams. In \nub_\mu mode, for the case of ,
is excluded, and for
, . The NuTeV data exclude the
high end of oscillations parameters
favored by the LSND experiment without the need to assume that the oscillation
parameters for and \nub are the same. We present the most stringent
experimental limits for
oscillations in the large region.Comment: 4 pages, 3 figures. Submitted to Phys. Rev. Letters, UR-164
Observation of an Anomalous Number of Dimuon Events in a High Energy Neutrino Beam
A search for long-lived neutral particles (N^0's) with masses above 2.2
GeV/c^2 that decay into at least one muon has been performed using an
instrumented decay channel at the NuTeV experiment at Fermilab. Data were
examined for particles decaying into the final states mu mu, mu e, and mu pi.
Three mu mu events were observed over an expected Standard Model background of
0.069 +/- 0.010 events; no events were observed in the other modes.Comment: 5 pages, 3 figures, Submitted to Phys. Rev. Let
Search for the Lepton Number Violating Process nu_mu-bar e^- -> mu^- nu_e-bar
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
Search for light-to-heavy quark flavor changing neutral currents in and scattering at the Tevatron
We report on a search for flavor-changing neutral-currents (FCNC) in the
production of heavy quarks in deep inelastic and scattering by the NuTeV experiment at the Fermilab Tevatron. This
measurement, made possible by the high-purity NuTeV sign-selected beams, probes
for FCNC in heavy flavors at the quark level and is uniquely sensitive to
neutrino couplings of potential FCNC mediators. All searches are consistent
with zero, and limits on the effective mixing strengths , , and are obtained
Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV
The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8 TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum
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