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H. Schellman

Publications and source records attributed to H. Schellman.

88 records · Page 5Linked to original sources

A Search for Muon-neutrino to Electron-neutrino and Muon-antineutrino to Electron-antineutrino Oscillations at NuTeV

Limits on $ν_μ\to ν_e$ and $\barν_μ\to \barν_e$ oscillations are extracted using the NuTeV detector with sign-selected $ν_μ$ and $\nub_μ$ beams. In $\nub_μ$ mode, for the case of $\sin^2 2α= 1$, $Δm^2 > 2.6$ ${\rm eV^2}$ is excluded, and for $Δm^2 \gg 1000$ ${\rm eV^2}$, $\sin^2 2α> 1.1 \times 10^{-3}$. The NuTeV data exclude the high $Δm^2$ end of $\barν_μ\to \barν_e$ oscillations parameters favored by the LSND experiment without the need to assume that the oscillation parameters for $ν$ and $\nub$ are the same. We present the most stringent experimental limits for $ν_μ(\barν_μ) \to ν_e (\barν_e)$ oscillations in the large $Δm^2$ region.

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The Potential for Neutrino Physics at Muon Colliders and Dedicated High Current Muon Storage Rings

Conceptual design studies are underway for muon colliders and other high-current muon storage rings that have the potential to become the first true ``neutrino factories''. Muon decays in long straight sections of the storage rings would produce precisely characterized beams of electron and muon type neutrinos of unprecedented intensity. This article reviews the prospects for these facilities to greatly extend our capabilities for neutrino experiments, largely emphasizing the physics of neutrino interactions.

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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.

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Observation of Anomalous Dimuon Events in the NuTeV Decay Detector

A search for long-lived neutral particles (N^0) which decay into at least one muon has been performed using an instrumented decay channel at the E815 (NuTeV) experiment at Fermilab. The decay channel was composed of helium bags interspersed with drift chambers, and was used in conjunction with the NuTeV neutrino detector to search for N^0 decays. The data were examined for particles decaying into the muonic final states mu mu, mu e, and mu pi. Three mu mu events were observed over an expected background of 0.040 +/- 0.009 events; no events were observed in the other modes. Although the observed events share some characteristics with neutrino interactions, the observed rate is a factor of 75 greater than expected. No Standard Model process appears to be consistent with this observation.

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Physics at a Neutrino Factory

In response to the growing interest in building a Neutrino Factory to produce high intensity beams of electron- and muon-neutrinos and antineutrinos, in October 1999 the Fermilab Directorate initiated two six-month studies. The first study, organized by N. Holtkamp and D. Finley, was to investigate the technical feasibility of an intense neutrino source based on a muon storage ring. This design study has produced a report in which the basic conclusion is that a Neutrino Factory is technically feasible, although it requires an aggressive R&D program. The second study, which is the subject of this report, was to explore the physics potential of a Neutrino Factory as a function of the muon beam energy and intensity, and for oscillation physics, the potential as a function of baseline.

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Parton Distributions Working Group

The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, we introduce a "Manifesto" that describes an optimal method for reporting data.

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Run II Jet Physics: Proceedings of the Run II QCD and Weak Boson Physics Workshop

The Run II jet physics group includes the Jet Algorithms, Jet Shape/Energy Flow, and Jet Measurements/Correlations subgroups. The main goal of the jet algorithm subgroup was to explore and define standard Run II jet finding procedures for CDF and DO. The focus of the jet shape/energy flow group was the study of jets as objects and the energy flows around these objects. The jet measurements/correlations subgroup discussed measurements at different beam energies; strong coupling constant measurements; and LO, NLO, NNLO, and threshold jet calculations. As a practical matter the algorithm and shape/energy flow groups merged to concentrate on the development of Run II jet algorithms that are both free of theoretical and experimental difficulties and able to reproduce Run I measurements. Starting from a review of the experience gained during Run I, the group considered a variety of cone algorithms and KT algorithms. The current understanding of both types of algorithms, including calibration issues, are discussed in this report along with some preliminary experimental results. The jet algorithms group recommends that CDF and DO employ the same version of both a cone algorithm and a KT algorithm during Run II. Proposed versions of each type of algorithm are discussed. The group also recommends the use of full 4-vector kinematic variables whenever possible. The recommended algorithms attempt to minimize the impact of seeds in the case of the cone algorithm and preclustering in the case of the KT algorithm. Issues regarding precluster definitions and merge/split criteria require further study.

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Evidence for Diffractive Charm Production in nu_mu Fe and nubar_mu Fe Scattering at the Tevatron

We present evidence for the diffractive processes nu_mu Fe -> mu^- D_s^+ (D_s^*+) Fe and nubar_mu Fe -> mu^+ D_s^- (D_s^*-) Fe using the Fermilab SSQT neutrino beam and the Lab E neutrino detector. We observe the neutrino trident reactions nu_mu Fe -> nu_mu mu^- mu^+ Fe and nubar_mu Fe -> nubar_mu mu^+ mu^- Fe at rates consistent with Standard Model expectations. We see no evidence for neutral-current production of J/psi via either diffractive or deep inelastic scattering mechanisms.

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Low Q^2 low x structure function analysis of CCFR data for F2

Analyses of structure functions (SFs) from neutrino and muon deep inelastic scattering data have shown discrepancies in F2 for x < 0.1. A new SF analysis of the CCFR collaboration data examining regions in x down to x=.0015 and 0.4 < Q^2 < 1.0 is presented. Comparison to corrected charged lepton scattering results for F2 from the NMC and E665 experiments are made. Differences between muon and neutrino scattering allow that the behavior of F2 from muon scattering could be different from F2 from neutrino scattering as Q^2 approaches zero. Comparisons between F2 muon and F2 neutrino are made in this limit.

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Charm Production at NuTeV

Neutrino deep-inelastic scattering provides a means to study both the strange and charm content of the nucleon. The NuTeV experiment (Fermilab E-8Neutrino deep-inelastic scattering provides a means to study both the strange and charm content of the nucleon. The NuTeV experiment (Fermilab E-815) takes full advantage of separated neutrino and anti-neutrino beams to probe the nucleon. The strange sea is studied with charged-current charm production resulting in an opposite-signed two muon final state. The charm content of the nucleon is probed via neutral-current charm production creating an event with a single wrong-signed muon. Preliminary results are presented for both analyses.

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Strange Content of the Nucleon (NuTeV)

The NuTeV experiment uses neutrino deep-inelastic scattering from separate neutrino and anti-neutrino beams to study the structure of the nucleon. Charged-current production of charm is sensitive to the strange content of the nucleon while neutral-current charm production probes the charm content. Preliminary analyses of both topics are presented along with discussion of possible momentum asymmetry in the strange sea.

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

The NuTeV experiment at Fermilab presents a determination of the electroweak mixing angle. High purity, large statistics samples of muon-neutrino and muon-antineutrino events allow the use of the Paschos-Wolfenstein relation. This considerably reduces systematic errors associated with charm production and other sources. With Standard Model assumptions, this measurement of sin2thw indirectly determines the W boson mass to a precision comparable to direct measurements from high energy e+e- and p-pbar colliders. NuTeV measures sin^2theta_W (on-shell) = 0.2253 +/- 0.0019(stat) +/- 0.0010(syst) which implies M_W = 80.26 +/- 0.11 GeV.

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Measurement of sin^2 theta_W in nu N Scattering from NuTeV

We report the measurement of sin^2 theta_W in nu N deep inelastic scattering from the NuTeV experiment. By using separate neutrino and anti-neutrino beams, NuTeV is able to determine sin^2 theta_W with smaller systematic and similar or smaller statistical errors when compared to previous neutrino experiments. NuTeV measures sin^2 theta_W (on-shell) = 0.2253 +/- 0.0019(stat.) +/- 0.0010(sys.), which implies M_W = 80.26 +/- 0.11 GeV/c^2.

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Measurements of the longitudinal structure function and |V_cs| in the CCFR experiment

Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F_2, xF_3(nu), xF_3(nubar) and R(longitudinal) in the kinematic region 0.01<x<0.6 and 1<Q^2<300 GeV^2. The new measurements of R in the x<0.1 region provide a constraint on the level of the gluon distribution. The x and Q^2 dependence of R is compared with a QCD based fit to previous data. The CKM matrix element |V_cs| is extracted from a combined analysis of xF_3 and dimuon data.

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Measurement of sin2thetaW from Neutrino-Nucleon Scattering at NuTeV

We report the measurement of sin2thetaW in neutrino-nucleon deep inelastic scattering from the NuTeV experiment. Using separate neutrino and anti-neutrino beams, NuTeV is able to determine sin2thetaW with low systematic errors by measuring the Paschos-Wolfenstein variable R-minus, a ratio of differences of neutrino and anti-neutrino neutral-current and charged-current cross-sections. NuTeV measures sin2thetaW(on-shell)= 0.2253+/-0.0019(stat)+/-0.0010(syst), which implies a W mass of 80.26+/-0.11 GeV.

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