Measurement of the ΔS=-ΔQ Amplitude from K_(e3)^0 Decay

We have measured the time distribution of the π^+e^-ν and π^-e^+ν modes from initial K^0's in a spark-chamber experiment performed at the Bevatron. From 1079 events between 0.2 and 7 K_S^0 lifetime, we find ReX=-0.069±0.036, ImX=+0.108_(-0.074)^(+0.092). This result is consistent with X=0 (relative probability = 0.25), but more than 4 standard deviations from the existing world average, +0.14 -0.13i

Measurement of the Luminosity in the ZEUS Experiment at HERA II

The luminosity in the ZEUS detector was measured using photons from electron bremsstrahlung. In 2001 the HERA collider was upgraded for operation at higher luminosity. At the same time the luminosity-measuring system of the ZEUS experiment was modified to tackle the expected higher photon rate and synchrotron radiation. The existing lead-scintillator calorimeter was equipped with radiation hard scintillator tiles and shielded against synchrotron radiation. In addition, a magnetic spectrometer was installed to measure the luminosity independently using photons converted in the beam-pipe exit window. The redundancy provided a reliable and robust luminosity determination with a systematic uncertainty of 1.7%. The experimental setup, the techniques used for luminosity determination and the estimate of the systematic uncertainty are reported.Comment: 25 pages, 11 figure

Neutral Currents in High-Energy Neutrino Collisions: An Experimental Search

A search for events with no final-state muon, as expected in the neutral-current interactions νμ(ν̅ μ)+N→νμ(ν̅ μ)+hadrons, has been carried out by using the California Institute of Technology-Fermilab neutrino detector and narrow-band neutrino beam. A clear signal of events with no apparent final-state muon has been observed. Furthermore, missing energy in the final state for these events provides strong evidence for the existence of a final-state ν

Gauge-Theory Heavy Muons: An Experimental Search

We have observed 1522 neutrino events with a μ- secondary and 8 events with a μ+ secondary from a beam consisting mostly of neutrinos. The μ+ events are consistent in number and kinematic properties with beam contamination by ν̅ μ. This experiment sees no evidence for production of heavy positively charged leptons. Assuming a coupling constant equal to the universal Fermi constant and a branching ratio to muons B=0.3, our 90% confidence lower limit corresponds to MY+≳8.4 GeV/c^2

Model independent analysis of the simultaneous mixing of gauge bosons and mixing of fermions

We discuss the case of simultaneous mixing of gauge bosons and mixing of fermions in a model independent way and for a variety of extra-fermion representations. In this context we analyze a class of lepton family violating processes, namely Z --> e tau, Z --> mu tau, Z --> e mu, mu --> e e e, tau --> e e e, tau --> mu mu mu, tau --> e mu mu and tau --> mu e e in the presence of one extra neutral gauge boson, Z', with universal, non-universal or family changing couplings. We derive bounds on the combined effect of Z-Z' mixing and ordinary--exotic lepton mixing.Comment: 13 pages, LaTeX, Submitted to Phys. Rev.

Mass Limit on a Positively Charged Heavy Muon

We report a preliminary search for a positively charged lepton (Y+) coupled directly to the μ- and νμ (i.e., muon number = + 1). Using the production process νμ+N→Y++anything, we have looked for the μ+ from the decay Y+→μ++νμ+νμ. The expected number of μ+ events is given as a function of the heavy-lepton mass, the branching fraction to muons, and the heavy-lepton coupling. For typical gauge-theory predictions, we obtain the 90% confidence limit MY>2 GeV/c^2

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

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