Nonperturbative renormalization of nonlocal quark bilinears for quasi-PDFs on the lattice using an auxiliary field

Quasi-PDFs provide a path toward an ab initio calculation of parton distribution functions (PDFs) using lattice QCD. One of the problems faced in calculations of quasi-PDFs is the renormalization of a nonlocal operator. By introducing an auxiliary field, we can replace the nonlocal operator with a pair of local operators in an extended theory. On the lattice, this is closely related to the static quark theory. In this approach, we show how to understand the pattern of mixing that is allowed by chiral symmetry breaking, and obtain a master formula for renormalizing the nonlocal operator that depends on three parameters. We present an approach for nonperturbatively determining these parameters and use perturbation theory to convert to the MS-bar scheme. Renormalization parameters are obtained for two lattice spacings using Wilson twisted mass fermions and for different discretizations of the Wilson line in the nonlocal operator. Using these parameters we show the effect of renormalization on nucleon matrix elements with pion mass approximately 370 MeV, and compare renormalized results for the two lattice spacings. The renormalized matrix elements are consistent among the different Wilson line discretizations and lattice spacings.Comment: 6 pages, 6 figures. v2: added perturbative matching to MS-bar and additional reference

Self-regulation and computer based learning

In recent years, interest in self-regulated learning has risen considerably. While self-regulatory activities are controlled cognitively, they encompass more than the monitoring of cognitive activities. Motivational and emotional processes are also important in learning and they too need to be regulated. At the same time, multimedia computer programs and theInternet have come to play un important role in present day 's learning environments. The question therefore arises as to what extent these new technologies facilitate the acquisition and improvement of self-regulated learning strategies. In the present article, we first explore the field of self-regulated learning and then try to come up with un answer to the question posed.En los últimos años, el interés por el aprendizaje autorregulado se ha desarrollado considerablemente. Aunque las actividades autorreguladas son controladas cognitivamente, abarcan más que el control de las actividades cognitivas. Los procesos motivacionales y emocionales también son importantes en el aprendizaje y también requieren ser controlados. Al mismo tiempo los programas multimedia e Internet han logrado unpapel importante en los entornos de aprendizaje y se presenta la pregunta de si las nuevas tecnologías facilitan la adquisición y el perfeccionamiento de las estrategias autorregulativas. En este articulo exploramos primero el campo de aprendizaje autorregulado y después tratamos de dar una respuesta a la pregunta planteada

E-rubrics to facilitate self-regulated learning

[ES] [Editorial]Steffens, K. (2014). E-rubrics to facilitate self-regulated learning. REDU. Revista de Docencia Universitaria. 12(1):11-12. https://doi.org/10.4995/redu.2014.6417111212

A Lattice Calculation of Parton Distributions

We present results for the $x$ dependence of the unpolarized, helicity, and transversity isovector quark distributions in the proton using lattice QCD, employing the method of quasi-distributions proposed by Ji in 2013. Compared to a previous calculation by us, the errors are reduced by a factor of about 2.5. Moreover, we present our first results for the polarized sector of the proton, which indicate an asymmetry in the proton sea in favor of the $u$ antiquarks for the case of helicity distributions, and an asymmetry in favor of the $d$ antiquarks for the case of transversity distributions.Comment: DIS2106 Proceeding

Transversity parton distribution functions from lattice QCD

We present the first direct calculation of the transversity parton distribution function within the nucleon from lattice QCD. The calculation is performed using simulations with the light quark mass fixed to its physical value and at one value of the lattice spacing. Novel elements of the calculations are non-perturbative renormalization and extraction of a formula for the matching to light-cone PDFs. Final results are presented in the $\overline{\rm MS}$ scheme at a scale of $\sqrt{2}$ GeV.Comment: 6 pages, 3 figures, 1 tabl

Systematic uncertainties in parton distribution functions from lattice QCD simulations at the physical point

We present a detailed study of the helicity-dependent and helicity-independent collinear parton distribution functions (PDFs) of the nucleon, using the quasi-PDF approach. The lattice QCD computation is performed employing twisted mass fermions with a physical value of the light quark mass. We give a systematic and in-depth account of the salient features entering in the evaluation of quasi-PDFs and their relation to the light-cone PDFs. In particular, we give details for the computation of the matrix elements, including the study of the various sources of systematic uncertainties, such as excited states contamination. In addition, we discuss the non-perturbative renormalization scheme used here and its systematics, effects of truncating the Fourier transform and different matching prescriptions.Comment: 47 pages, 33 figures, 6 table

Self-regulated and Technology-enhanced learning: a European perspective

Self-regulation of learning, learning to learn, and their potential stimulation by specific Information and Communication Technologies (ICTs), are main topics in European policy. This issue of the ‘European Educational Research Journal’ (EERJ) focuses on research to develop, integrate, and evaluate self-regulation of learning and the potential and actual uses of ICTs in educational practice. In this paper, we introduce five articles on self-regulated and technology-enhanced learning representing development and research conducted in preschools, primary and secondary schools, and universities of various countries. This research was presented at two symposia of the ‘European Conference on Educational Research’ (ECER) in Cádiz (2012). The symposia were part of the ECER network 16 ‘ICT in education and training’. The research exemplifies three different models of ICT-based learning, ranging from ‘traditional’ via ‘more flexible’ to ‘optimal’ learning. We discuss the main characteristics and outcomes of the five articles. We conclude with theoretical and methodological aspects that may promote further development and research of self-regulated and technology-enhanced learning in a European perspective