Angular Momentum Decomposition for an Electron

We calculate the orbital angular momentum of the `quark' in the scalar diquark model as well as that of the electron in QED (to order $\alpha$). We compare the orbital angular momentum obtained from the Jaffe-Manohar decomposition to that obtained from the Ji relation and estimate the importance of the vector potential in the definition of orbital angular momentum

Spin structure of the pion from the instanton vacuum

We investigate the spin structure of the pion within the framework of the nonlocal chiral quark model from the instanton vacuum. We first evaluate the tensor form factors of the pion for the first and second moment (n=1,2) and compare it with the lattice data. Combining the tensor form factor of the pion with the electromagnetic one, we determine the impact-parameter dependent probability density of transversely polarized quarks inside the pion. It turns out that the present numerical results for the tensor form factor as well as those for the probability density are in good agreement with the lattice data. We also discuss the distortion of the spatial distribution of the quarks in the transverse plane inside the pion.Comment: 9 pages, 10 figures, accepted for publication in Phys. Lett.

Renormalization constants of local operators for Wilson type improved fermions

Perturbative and non-perturbative results are presented on the renormalization constants of the quark field and the vector, axial-vector, pseudoscalar, scalar and tensor currents. The perturbative computation, carried out at one-loop level and up to second order in the lattice spacing, is performed for a fermion action, which includes the clover term and the twisted mass parameter yielding results that are applicable for unimproved Wilson fermions, as well as for improved clover and twisted mass fermions. We consider ten variants of the Symanzik improved gauge action corresponding to ten different values of the plaquette coefficients. Non-perturbative results are obtained using the twisted mass Wilson fermion formulation employing two degenerate dynamical quarks and the tree-level Symanzik improved gluon action. The simulations are performed for pion masses in the range of 480 MeV to 260 MeV and at three values of the lattice spacing, a, corresponding to beta=3.9, 4.05, 4.20. For each renormalization factor computed non-perturbatively we subtract its perturbative O(a^2) terms so that we eliminate part of the cut-off artifacts. The renormalization constants are converted to MS-bar at a scale of mu=2 GeV. The perturbative results depend on a large number of parameters and are made easily accessible to the reader by including them in the distribution package of this paper, as a Mathematica input file.Comment: 36 pages, 11 figures and 6 tables. The results are included in electronic form (Mathematica files

Minnesota Historical and Cultural Heritage (Legacy) Grant Program: LSA Survey Results and Recommendations

In August 2017, the Legacy Strategic Agenda (LSA) Collaborative Priority Action Team (PAT) for Grants conducted a survey of Minnesota cultural heritage organizations about the Minnesota Historical and Cultural Heritage (Legacy) grant program managed by the Minnesota Historical Society. The presenters will provide a background about the survey and share the results and recommendations that came out of the survey

Legacy Grants: Assessment, Feedback, & Action

Members of the Legacy Strategic Agenda (LSA) Grants Priority Action Team (PAT) will provide an update on the recommendations presented at last year’s MALHM conference. The session will include: A quick overview of our assessment process and the recommendations that were developed Information on how feedback from the 2018 MALHM conference impacted the process Recommendation prioritization and implementation timeline Implementation updates The session will conclude with an opportunity for attendees to provide additional feedback on the project

Gravitational and higher-order form factors of the pion in chiral quark models

The gravitational form factor of the pion is evaluated in two chiral quark models and confronted to the recent full-QCD lattice data. We find good agreement for the case of the Spectral Quark Model, which builds in the vector-meson dominance for the charge form factor. We derive a simple relation between the gravitational and electromagnetic form factors, holding in the considered quark models in the chiral limit. The relation implies that the gravitational mean squared radius is half the electromagnetic one. We also analyze higher-order quark generalized form factors of the pion, related to higher moments in the symmetric Bjorken X-variable of the generalized parton distribution functions, and discuss their perturbative QCD evolution, needed to relate the quark-model predictions to the lattice data. The values of the higher-order quark form factors at t=0, computed on the lattice, also agree with our quark model results within the statistical and method uncertainties.Comment: 12 pages, 4 figures, discussion and references adde

Moments of generalized parton distributions and quark angular momentum of the nucleon

The internal structure of hadrons is important for a variety of topics, including the hadron form factors, proton spin and spin asymmetry in polarized proton scattering. For a systematic study generalized parton distributions (GPDs) encode important information on hadron structure in the entire impact parameter space. We report on a computation of nucleon GPDs based on simulations with two dynamical non-perturbatively improved Wilson quarks with pion masses down to 350MeV. We present results for the total angular momentum of quarks with chiral extrapolation based on covariant baryon chiral perturbation theory.Comment: Presented at 25th International Symposium on Lattice Field Theory, Regensburg, Germany, 30 Jul - 4 Aug 200

Low-Lying Nucleons from Chirally Improved Fermions

We report on our preliminary results on the low-lying excited nucleon spectra which we obtain through a variational basis formed with three different interpolators.Comment: Contributed to Lattice 2003(spectrum), Tsukub

The pion mass dependence of the nucleon form-factors of the energy momentum tensor in the chiral quark-soliton model

The nucleon form factors of the energy-momentum tensor are studied in the large-Nc limit in the framework of the chiral quark-soliton model for model parameters that simulate physical situations in which pions are heavy. This allows for a direct comparison to lattice QCD results.Comment: 17 pages, 12 figure

Flavor Twisted Boundary Conditions, Pion Momentum, and the Pion Electromagnetic Form Factor

We investigate the utility of partially twisted boundary conditions in lattice calculations of meson observables. For dynamical simulations, we show that the pion dispersion relation is modified by volume effects. In the isospin limit, we demonstrate that the pion electromagnetic form factor can be computed on the lattice at continuous values of the momentum transfer. Furthermore, the finite volume effects are under theoretical control for extraction of the pion charge radius.Comment: 15 pages, 8 figures, revisions to text, refs adde