arXiv subjects

Tim Stelzer

Publications and source records attributed to Tim Stelzer.

11 recordsLinked to original sources

arXiv2026

Teacher Leader Identity Development in a Physics Teaching Community of Practice: A Narrative Case Study

This longitudinal narrative case study examines the leadership identity development of Kayla, a female high school physics teacher, across five years of participation in a community of practice (CoP). Drawing on multiple data sources, we trace how her participation evolved from classroom-level practice to broader institutional influence. Four interconnected dimensions of leadership identity development were identified: personal, social, practice, and institutional culture change. Findings show how CoP membership provided collective legitimacy and relational support that enabled Kayla to move beyond identity negotiation toward transformation , successfully advocating for an AP Physics course and increasing female student participation. This study contributes to teacher professional learning literature by demonstrating the value of an identity lens for understanding teacher leadership as a gradual, socially enabled process. The longitudinal design reveals transformative conditions that cross-sectional studies often obscure, highlighting narrative case study as a productive methodology for capturing teacher leadership identity development over time.

physics.ed-ph↗

arXiv2024

Teachers' Experiences with Implementing Open-ended Labs in High School Physics Classe

Although most teachers acknowledge the importance of taking investigative approached in students' science learning experiences, implementing them in high-school classes can be challenging for teachers. In this work, we analyzed data from multiple sources from a teaching Community of Practice (CoP) to investigate (a) barriers to using open-ended labs in physics classes, (b) shifts in teachers' beliefs about the use of open-ended labs in their classes during teachers' engagement in a physics teacher CoP in a partnership program, and (c) a case study of one teachers whose shifts in perceptions about open-ended labs led to her successful implementation of an open-ended lab in her class. The findings confirm the existence of well-known psychological and structural barriers that can prevent teachers from adopting investigative approaches in teaching physics labs. Moreover, we learned how the interaction of these barriers further complicates the adoption of open-ended approaches in physics classes. The study also revealed a significant gap between teachers' current practices and their desired method for conducting labs, particularly in terms of structured versus open-ended approaches. The case study offered deeper insights into how shifts in teaching practices occur through changes in perceptions within a supportive CoP.

physics.ed-ph↗

arXiv2023

Navigating Socio-Emotional Risk through Comfort-Building in a Physics Teaching Community of Practice: A Case Study

In teacher professional development (PD), grouping teachers with varying levels of experience can be a productive and empowering way to stimulate the exchange and co-generation of content and pedagogical knowledge. However, less experienced teachers can face socio-emotional risks when engaging in collaborative science content reasoning tasks with more experienced colleagues (Finkelstein, Jaber, & Dini, 2018), and these risks may impact the collaborative experience of both parties and the learning environment in teacher PD. This descriptive case study examines the process of productively navigating socio-emotional risks and interpersonal tensions encountered by a veteran and pre-service physics teacher during one episode of discussing physics content. We use a single term, comfort-building, to encapsulate discursive moves that result in increased feelings of comfort and safety by the participants. Comfort-building includes moves that serve to mitigate social risk, ease tension, and avoid discomfort, as well as those geared toward finding common ground and co-navigating challenges. These moves can carve out conversational space for teachers to more confidently face risks associated with being accountable to the physics content knowledge and engage in discipline-based conversations more deeply. The presented episode in this study was followed by video-stimulated individual interviews to determine how consciously the teachers connected their participation to explicit risk and comfort. This case study highlights an affective dimension for consideration in the continued study and facilitation of science teaching communities of practice, especially ones that bring together teachers with a variety of backgrounds and skill sets.

physics.ed-ph↗

arXiv2023

Responsive Professional Development: A Facilitation Approach for Teachers' Development in a Physics Teaching Community of Practice

Creating learning environments that can accommodate teachers' diverse needs is challenging because responsive elements are not clearly defined or identified. This study identified responsive teacher professional development (PD) elements by taking a phenomenological approach. Using surveys and interviews with 13 high school physics teachers in a PD program at a Midwestern university, we identified responsive features such as practicality, flexibility, and accessibility core to the enactment of a responsive PD. Other features were opportunities for community engagement, pedagogical support, and professional growth, which were aligned with the benefits of engagement in a Community of Practice model incorporated in this work.

physics.ed-ph↗

arXiv2012

Effective Field Theory: A Modern Approach to Anomalous Couplings

We advocate an effective field theory approach to anomalous couplings. The effective field theory approach is the natural way to extend the standard model such that the gauge symmetries are respected. It is general enough to capture any physics beyond the standard model, yet also provides guidance as to the most likely place to see the effects of new physics. The effective field theory approach also clarifies that one need not be concerned with the violation of unitarity in scattering processes at high energy. We apply these ideas to pair production of electroweak vector bosons.

hep-ph↗

arXiv2011

ALOHA: Automatic Libraries Of Helicity Amplitudes for Feynman diagram computations

We present an application that automatically writes the Helas library corresponding to the Feynman rules of any Lagrangian, renormalizable or not, in quantum field theory. The code, written in Python, takes the Universal FeynRules Output as an input and produces the complete set of routines (wave-functions and amplitudes) that are needed for the computation of Feynman diagrams at leading as well as at higher orders. The representation is language independent and outputs in Fortran, C++, Python are currently available. A few key sample applications implemented in the MadGraph5 framework are presented.

hep-ph↗

arXiv2011

MadGraph 5 : Going Beyond

MadGraph 5 is the new version of the MadGraph matrix element generator, written in the Python programming language. It implements a number of new, efficient algorithms that provide improved performance and functionality in all aspects of the program. It features a new user interface, several new output formats including C++ process libraries for Pythia 8, and full compatibility with FeynRules for new physics models implementation, allowing for event generation for any model that can be written in the form of a Lagrangian. MadGraph 5 builds on the same philosophy as the previous versions, and its design allows it to be used as a collaborative platform where theoretical, phenomenological and simulation projects can be developed and then distributed to the high-energy community. We describe the ideas and the most important developments of the code and illustrate its capabilities through a few simple phenomenological examples.

hep-ph↗

arXiv2009

Automation of next-to-leading order computations in QCD: the FKS subtraction

We present the complete automation of the universal subtraction formalism proposed by Frixione, Kunszt, and Signer for the computation of any cross section at the next-to-leading order in QCD. Given a process, the only ingredient to be provided externally is the infrared- and ultraviolet-finite contribution of virtual origin. Our implementation, currently restricted to the case of e+e- collisions, is built upon and works in the same way as MadGraph. It is particularly suited to parallel computation, and it can deal with any physical process resulting from a theory implemented in MadGraph, thus including the Standard Model as well as Beyond the Standard Model theories. We give results for some sample processes that document the performances of the implementation, and show in particular how the number of subtraction terms has an extremely mild growth with final-state multiplicity.

hep-ph↗

arXiv2007

MadGraph/MadEvent v4: The New Web Generation

We present the latest developments of the MadGraph/MadEvent Monte Carlo event generator and several applications to hadron collider physics. In the current version events at the parton, hadron and detector level can be generated directly from a web interface, for arbitrary processes in the Standard Model and in several physics scenarios beyond it (HEFT, MSSM, 2HDM). The most important additions are: a new framework for implementing user-defined new physics models; a standalone running mode for creating and testing matrix elements; generation of events corresponding to different processes, such as signal(s) and backgrounds, in the same run; two platforms for data analysis, where events are accessible at the parton, hadron and detector level; and the generation of inclusive multi-jet samples by combining parton-level events with parton showers. To illustrate the new capabilities of the package some applications to hadron collider physics are presented: 1) Higgs search in pp \to H \to W^+W^-: signal and backgrounds. 2) Higgs CP properties: pp \to H jj$in the HEFT. 3) Spin of a new resonance from lepton angular distributions. 4) Single-top and Higgs associated production in a generic 2HDM. 5) Comparison of strong SUSY pair production at the SPS points. 6) Inclusive W+jets matched samples: comparison with the Tevatron data.

hep-ph↗

arXiv2006

Higgs at the Tevatron in Extended Supersymmetric Models

Supersymmetric models with an additional singlet field offer the Higgs boson the possibility to decay to two pseudoscalars, a. If the mass of these pseudoscalars is above the b bbar threshold, a -> b bbar is generically the dominant decay mode. The decay h -> a a -> b bbar b bbar may be seen above backgrounds at the Tevatron if the Higgs production cross section is enhanced relative to that of the standard model.

hep-ph↗

arXiv2002

MadEvent: Automatic Event Generation with MadGraph

We present a new multi-channel integration method and its implementation in the multi-purpose event generator MadEvent, which is based on MadGraph. Given a process, MadGraph automatically identifies all the relevant subprocesses, generates both the amplitudes and the mappings needed for an efficient integration over the phase space, and passes them to MadEvent. As a result, a process-specific, stand-alone code is produced that allows the user to calculate cross sections and produce unweighted events in a standard output format. Several examples are given for processes that are relevant for physics studies at present and forthcoming colliders.

hep-ph↗