10612500
Measurement of kinematic and nuclear dependence of R= sigma L/ sigma T in deep inelastic electron scattering.
We report results on a precision measurement of the ratio R=σ_L/σ_T in deep inelastic electron-nucleon scattering in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤10 (GeV/c)^2. Our results show, for the first time, a clear falloff of R with increasing Q^2. Our R results are in agreement with QCD predictions only when corrections for target mass effects and some additional higher twist effects are included. At small x, the data on R favor structure functions with a large gluon contribution. We also report results on the differences R_A-R_D and the cross section ratio σ^A/σ^D between Fe and Au nuclei and the deuteron. Our results for R_A-R_D are consistent with zero for all x, Q^2 indicating that possible contributions to R from nuclear higher twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The ratios σ^A/σ^D from all recent experiments, at all x, Q^2 values, are now in agreement.
6465772
First measurements of inclusive muon neutrino charged current differential cross sections on argon.
The ArgoNeuT Collaboration presents the first measurements of inclusive muon neutrino charged current differential cross sections on argon. Obtained in the NuMI neutrino beam line at Fermilab, the flux-integrated results are reported in terms of outgoing muon angle and momentum. The data are consistent with the Monte Carlo expectation across the full range of kinematics sampled, 0°<θ(μ)<36° and 0<P(μ)<25 GeV/c. Along with confirming the viability of liquid argon time projection chamber technology for neutrino detection, the measurements allow tests of low-energy neutrino scattering models important for interpreting results from long baseline neutrino oscillation experiments designed to investigate CP violation and the orientation of the neutrino mass hierarchy.
120734789
Working Group Report: Neutrinos
125351714
A Proposal for a Precision Measurement of the Decay K+ --> pi+ neutrino antineutrino and Other Rare K+ Processes at Fermilab Using the Main Injector
1036381
Measurement of neutrino oscillations with the MINOS detectors in the NuMI beam.
This Letter reports new results from the MINOS experiment based on a two-year exposure to muon neutrinos from the Fermilab NuMI beam. Our data are consistent with quantum-mechanical oscillations of neutrino flavor with mass splitting |Deltam2| = (2.43+/-0.13) x 10(-3) eV2 (68% C.L.) and mixing angle sin2(2theta) > 0.90 (90% C.L.). Our data disfavor two alternative explanations for the disappearance of neutrinos in flight: namely, neutrino decays into lighter particles and quantum decoherence of neutrinos, at the 3.7 and 5.7 standard-deviation levels, respectively.
7055987
Measurement of the background in the NEMO 3 double beta decay experiment
In the double beta decay experiment NEMO 3 a precise knowledge of the background in the signal region is of outstanding importance. This article presents the methods used in NEMO 3 to evaluate the backgrounds resulting from most if not all possible origins. It also illustrates the power of the combined tracking-calorimetry technique used in the experiment.
6566814
Renormalization flow in lattice QED.
An investigation of pure U(1) gauge theory is made based on block-spin transformations for configurations of lattice size 16/sup 4/ down to size 8/sup 4/ and 4/sup 4/. Even operators (five types in the first three representations) and ten renormalized couplings are determined on these smaller lattices. This allows the mapping of the renormalization flow. An interesting fixed-point structure and results on the leading critical exponent are found.
45279636
Even and odd critical exponents of lattice QED.
The theory is simulated for Villain's action on ${16}^{4}$ lattices. Block-spin transformations of two different types to ${8}^{4}$, ${4}^{4}$, and ${2}^{4}$ are performed. We estimate the leading even and odd critical exponents and discuss the fixed-point structure of the theory.
18949257
Four-dimensional pure compact U(1) gauge theory on a spherical lattice.
We investigate the confinement-Coulomb phase transition in the four-dimensional (4D) pure compact U(1) gauge theory on spherical lattices. The action contains the Wilson coupling {beta} and the double-charge coupling {gamma}. The lattice is obtained from the 4D surface of the 5D cubic lattice by its radial projection onto a 4D sphere, and made homogeneous by means of appropriate weight factors for individual plaquette contributions to the action. On such lattices the two-state signal, impeding the studies of this theory on toroidal lattices, is absent for {gamma}{le}0. Furthermore, here a consistent finite-size scaling behavior of several bulk observables is found, with the correlation length exponent {nu} in the range {nu}=0.35{minus}0.40. These observables include Fisher zeros, specific-heat, and cumulant extrema as well as pseudocritical values of {beta} at fixed {gamma}. The most reliable determination of {nu} by means of the Fisher zeros gives {nu}=0.365(8). The phase transition at {gamma}{le}0 is thus very probably of second order and belongs to the universality class of a non-Gaussian fixed point. {copyright} {ital 1996 The American Physical Society.}
42431244
Properties of phase transitions of the lattice SU(2) Higgs model.
We discuss the phase structure of the lattice-gauge--Higgs model for the gauge group SU(2) and Higgs fields in the fundamental representation with a dynamical radial mode. We find that the confinement-Higgs phase transition is of first order for small phi/sup 4/ coupling lambda but weakens with increasing lambda. Correlations of bound-state operators on the phase-transition point at lambda = 0.5, ..beta.. = 2.25 on a 8/sup 3/ x 16 lattice show a scalar state with the mass of 0.2 inverse lattice spacings and a four-times-heavier vector isotriplet.
331070
Complex actions for fermions in higher dimensions.
We discuss the generalization of the complex Langevin approach to fermionic path integrals for more than d = 1+1 dimensions. Whereas one found convincing results in dless than or equal to1+1 there are difficulties with the convergence properties of the complex processes even for free relativistic fermions for d = 2+1. Satisfactory results are obtained only for very small lattices or in a certain asymmetric limit of the coupling parameters.