ABSTRACT
We present a new measurement of the difference between the nucleon strange and antistrange quark distributions from dimuon events recorded by the NuTeV experiment at Fermilab. This analysis is the first to use a complete next to leading order QCD description of charm production from neutrino scattering. Dimuon events in neutrino deep inelastic scattering allow direct and independent study of the strange and antistrange content of the nucleon. We find a positive strange asymmetry with a significance of 1.6sigma. We also report a new measurement of the charm mass.
ABSTRACT
Limits on nu(mu)-->nu(e) and nu(mu)-->nu(e) oscillations are extracted using the NuTeV detector with sign-selected nu(mu) and nu(mu) beams. In nu(mu) mode, for the case of sin(2)2alpha = 1, Delta(m)(2)>2.6 eV(2) is excluded, and for Delta(m)(2)>>1000 eV(2), sin(2)2alpha>1.1 x 10(-3). The NuTeV data exclude the high Delta(m)(2) end of nu(mu)-->nu(e) oscillation parameters favored by the LSND experiment without the need to assume that the oscillation parameters for nu and nu are the same. We present the most stringent experimental limits for nu(mu)(nu(mu))-->nu(e)(nu(e)) oscillations in the large Delta(m)(2) region.
ABSTRACT
The NuTeV Collaboration has extracted the electroweak parameter sin(2)theta(W) from the measurement of the ratios of neutral current to charged current nu and (-)nu cross sections. Our value, sin(2)theta((on-shell))(W) = 0.2277 +/- 0.0013(stat) +/- 0.0009(syst), is 3 standard deviations above the standard model prediction. We also present a model independent analysis of the same data in terms of neutral-current quark couplings.
ABSTRACT
We report on the extraction of R = sigma(L)/sigma(T) from CCFR nu(mu)-Fe and nu(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 uses NNLO parton distribution functions and 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).
ABSTRACT
The NuTeV experiment at Fermilab has used a sign-selected neutrino beam to perform a search for the lepton number violating process nu(mu)e(-)-->mu(-)nu(e), 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 slope 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 cross-section ratio sigma(nu(mu)e(-)-->mu(-)nu(e))/sigma(nu(mu)e(-)-->mu(-)nu(e)) < or = 1.7% at 90% C.L. for V-A couplings and < or = 0.6% for scalar couplings.
ABSTRACT
A search for long-lived neutral particles ( N0'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 mumu, mu(e), and mu(pi). Three mumu events were observed over an expected standard model background of 0.069+/-0.010 events; no events were observed in the other modes.
ABSTRACT
A new structure function analysis of CCFR deep inelastic nu-N and nu-N scattering data is presented for previously unexplored kinematic regions down to Bjorken x = 0.0045 and Q(2) = 0.3 GeV(2). Comparisons to charged lepton scattering data from NMC and E665 experiments are made and the behavior of the structure function F(2)(nu)2 is studied in the limit Q(2)-->0.
ABSTRACT
We report on the extraction of the structure functions F2 and DeltaxF(3) = xF(nu)(3)-xF(nu;)(3) from CCFR nu(mu)-Fe and nu;(mu)-Fe differential cross sections. The extraction is performed in a physics model-independent (PMI) way. This first measurement of DeltaxF(3), which is useful in testing models of heavy charm production, is higher than current theoretical predictions. The ratio of the F2 (PMI) values measured in nu(mu) and mu scattering is in agreement (within 5%) with the predictions of next-to-leading-order parton distribution functions using massive charm production schemes, thus resolving the long-standing discrepancy between the two sets of data.
ABSTRACT
Seizures are a recognized manifestation of neurosarcoidosis, but their clinical relevance is not well established. We reviewed the characteristics, clinical correlations, and prognosis of seizures in 79 patients with neurosarcoidosis. Thirteen (15%) of the 79 patients had seizures, and in eight patients (10%) a seizure was the first manifestation of neurosarcoidosis. These seizures were generalized tonic-clonic seizures in 12 patients (92%) and partial seizures in four patients (31%). The patients with neurosarcoidosis with seizures were more likely to have a progressive or relapsing clinical course and intracranial mass lesions (four patients [31%]), encephalopathy or vasculopathy (eight patients [62%]), or hydrocephalus (five patients [38%]). These central nervous system disorders, rather than the seizures per se, were responsible for most of the serious morbidity and the two deaths (15%) among our patients with seizures. Indeed seizure control was good in 11 (85%) of 13 patients treated with combinations of steroids and antiepileptic medications. Seizures are an important sign in neurosarcoidosis because they are associated with more severe and progressive or relapsing forms of central nervous system sarcoidosis and may be an early manifestation of such disorders.
