How well do we know the neutron structure function?

We present a detailed analysis of the uncertainty in the neutron F2n structure function extracted from inclusive deuteron and proton deep-inelastic scattering data. The analysis includes experimental uncertainties as well as uncertainties associated with the deuteron wave function, nuclear smearing, and nucleon off-shell corrections. Consistently accounting for the Q^2 dependence of the data and calculations, and restricting the nuclear corrections to microscopic models of the deuteron, we find significantly smaller uncertainty in the extracted F2n/F2p ratio than in previous analyses. In addition to yielding an improved extraction of the neutron structure function, this analysis also provides an important baseline that will allow future, model-independent extractions of neutron structure to be used to examine nuclear medium effects in the the deuteron.Comment: 5 pages, 6 figure

Coherent π^0 photoproduction on the deuteron up to 4 GeV

The differential cross section for ^2H(γ,d)π^0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions

Electromagnetic proton form factors in large NcN_{c} QCD

The electromagnetic form factors of the proton are obtained using a particular realization of QCD in the large $N_c$ limit (${QCD}_{\infty}$), which sums up the infinite number of zero-width resonances to yield an Euler's Beta function (Dual-${QCD}_{\infty}$). The form factors $F_1(q^2)$ and $F_2(q^2)$, as well as $G_M(q^2)$ agree very well with reanalyzed space-like data in the whole range of momentum transfer. In addition, the predicted ratio $\mu_p G_E/G_M$ is in good agreement with recent polarization transfer measurements at Jefferson Lab.Comment: 10 page

Neutron Structure Functions

Neutron structure functions can be extracted from proton and deuteron data and a representation of the deuteron structure. This procedure does not require DIS approximations or quark structure assumptions. We find that the results depend critically on properly accounting for the Q^2 dependence of proton and deuteron data. We interpolate the data to fixed Q^2, and extract the ratio of neutron to proton structure functions. The extracted ratio decreases with increasing x, up to x \approx 0.9, while there are no data available to constrain the behavior at larger x.Comment: 16 pages, 6 figure

Wroclaw neutrino event generator

A neutrino event generator developed by the Wroclaw Neutrino Group is described. The physical models included in the generator are discussed and illustrated with the results of simulations. The considered processes are quasi-elastic scattering and pion production modelled by combining the $\Delta$ resonance excitation and deep inelastic scattering.Comment: Talk given at 2nd Scandanavian Neutrino Workshop (SNOW 2006), Stockholm, Sweden, 2-6 May 2006. 3 pages, 6 figure

Extraction of the Axial Nucleon Form Factor from Neutrino Experiments on Deuterium

We present new parameterizations of vector and axial nucleon form factors. We maintain an excellent descriptions of the form factors at low momentum transfers ($Q^2$), where the spatial structure of the nucleon is important, and use the Nachtman scaling variable $\xi$ to relate elastic and inelastic form factors and impose quark-hadron duality constraints at high $Q^2$ where the quark structure dominates. We use the new vector form factors to re-extract updated values of the axial form factor from \numu experiments on deuterium. We obtain an updated world average value from \numud, \numubarH and pion electroproduction experiments of $M_{A}$ = $1.014 \pm 0.014 GeV/c^2$. Our parameterizations are useful in modeling $\nu$ interactions at low energies (e.g. for \numu oscillations experiments). The predictions for high $Q^2$ can be tested in the next generation electron and \numu scattering experiments.Comment: Presented by A. Bodek at the European Physical Society Meeting, EPS2007, Manchester, England, July 2007, 4 pages, 2 figure

Evidence for virtual Compton scattering from the proton

In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation

Momentum Transfer Dependence of Nuclear Transparency from the Quasielastic ^(12)C(e, e'p) Reaction

The cross section for quasielastic ^(12)C(e,e’p) scattering has been measured at momentum transfer Q^2=1, 3, 5, and 6.8 (GeV/c)^2. The results are consistent with scattering from a single nucleon as the dominant process. The nuclear transparency is obtained and compared with theoretical calculations that incorporate color transparency effects. No significant rise of the transparency with Q^2 is observed