Higher derivative three-form gauge theories and their supersymmetric extension

We investigate three-form gauge theories with higher derivative interactions and their supersymmetric extensions in four space-time dimensions. For the bosonic three-form gauge theories, we show that derivatives on the field strength of the 3-form gauge field yield a tachyon as far as the Lagrangian contains a quadratic kinetic term, while such the term with opposite sign gives rise to a ghost. We confirm that there is neither a tachyon nor a ghost when all higher derivative terms are given by functions of the field strength. For this ghost/tachyon-free Lagrangian, we determine the boundary term necessary for the consistency between the equation of motion and energy-momentum tensor. For supersymmetric extensions, we present ghost/tachyon-free higher derivative interactions of arbitrary order of the field strength and corresponding boundary terms as well.Comment: 46 pages; v2: references added, published versio

Spatially Modulated Vacua in a Lorentz-invariant Scalar Field Theory

Spatial modulation has been studied for a long time in condensed matter, nuclear matter and quark matter, so far in non-relativistic field theories. In this paper, spatially modulated vacua at zero temperature and zero density are studied in relativistic field theories. We first propose an adaptation of the Nambu-Goldstone theorem to higher derivative theories under the assumption of the absence of ghosts: when a global symmetry is spontaneously broken due to vacuum expectation values of space-time derivatives of fields, a Nambu-Goldstone (NG) boson appears without a canonical kinetic (quadratic derivative) term with a quartic derivative term in the modulated direction while a Higgs boson appears with a canonical kinetic term. We demonstrate this in a simple model allowing (meta)stable modulated vacuum of a phase modulation (Fulde-Ferrell state), where an NG mode associated with spontaneously broken translational and $U(1)$ symmetries appears.Comment: 20 pages, 3 figures, title changed, published versio

The focus-on-form effects of strategic and on-line planning : an analysis of Japanese oral performance and verbal reports

Within the framework of task-based language learning, there has been much research on planning, under the premise that learners' language would be enhanced in planned conditions. However, the underlying mechanisms ofthis rationale have not been fully explored. To develop the present understanding, this study aims to explore the nature of planning and the psycholinguistic mechanisms of its effects on L2 performance. Earlier planning research has tended to focus on 'strategic planning' (i.e., a period of time given prior to a task), suggesting that it may improve learners' language in terms of fluency and complexity but not always in accuracy (e.g., Crookes, 1989, Foster & Skehan, 1996). In response to this, Yuan and Ellis (2003) propose 'on-line planning' (i.e., on-line processing pressure is lessened to allow active formulation and monitoring) and show its positive effect on accuracy as well as complexity. Building on these previous studies, the purpose of this research is to investigate the different form-focused effects between strategic and on-line planning. The study takes a process-product approach to planning by using a quantitative analysis of oral performance and a qualitative analysis of post-task verbal reports, prompted by stimulated recall, under non-planning, strategic planning and on-line planning conditions. The analysis of the performance of twenty-seven Japanese learners of English (grouped as high vs. low proficiency levels) demonstrates the positive effects of strategic planning on complexity and those of on-line planning on complexity and accuracy. Most importantly, different planning effects on specific accuracy measures were observed between different proficiency groups - verb forms in the low-proficiency and articles in the high-proficiency group. To complement the results of the performance analysis, the examination of verbal reports presents participants' planning processes. To support the improvement in accuracy in on-line planning, the analysis reveals that pressured conditions (i.e., non-planning and strategic planning) made participants prioritize meaning over form; on the other hand, on-line planning tended to push them into more complex structures while maintaining certain attention to accuracy. Drawing on pedagogical considerations offocus-on-form instruction, this thesis argues that strategic planning and on-line planning have different degrees of form-focused effects. In particular, on-line planning, beyond a simple improvement of accuracy, would increase consciousness of form and bring L2 learners to deeper, syntactic processing. It is suggested that some kind of on-line planning would be useful for developing learners' abilities of syntactic formulation

Understanding motivation-in-action from a Dynamic Systems Approach

We report on part of an ongoing longitudinal study on students\u27 motivational changes in EFL classrooms. Research on second language (L2) motivation has traditionally focused on a static state, or what type of motivation contributes to successful L2 learning, but such choice motivation is different from executive motivation needed for sustaining a long period of learning. Drawing on a process model of L2 motivation (Dornyei & Otto, 1998), this study examines how first year university students\u27 executive motivation changes from the beginning to the end of EFL courses over one year (n=164). In addition to pre-course and post-course questionnaires, short weekly questionnaires are provided at the end of every class for self-assessing students\u27 own motivation towards the class. Together with qualitative analysis of teacher reflection, the findings uncover underlying reasons for motivational fluctuation and evolution in EFL classrooms

Form-focused tasks in ELT coursebooks: A framework for analysis

Current grammar pedagogies tend to reflect the influence of recent SLA research in favour of input-processing rather than skill-building models. The detailed impact of these pedagogies and research on contemporary teaching materials, however, is less clear. This paper proposes a framework of criterial features of consciousness-raising (C-R) and practice tasks which is then used to explore the relationships between the features, and to investigate the nature and sequencing of form-focused tasks in ELT coursebooks. This research reveals an incremental shift from less interactional, input-based tasks to more interactional, production-based tasks through the teaching stages. More importantly, most materials use several types of form-focused tasks in rather fixed sequential patterns of interpretation tasks to grammar consciousness raising tasks to grammar exercises to grammar practice activities which follow a meaning → meaning>form → form/meaning → meaning progression. Theoretical explanations are offered in support of this data-driven model