QPACE 2 and Domain Decomposition on the Intel Xeon Phi

We give an overview of QPACE 2, which is a custom-designed supercomputer based on Intel Xeon Phi processors, developed in a collaboration of Regensburg University and Eurotech. We give some general recommendations for how to write high-performance code for the Xeon Phi and then discuss our implementation of a domain-decomposition-based solver and present a number of benchmarks.Comment: plenary talk at Lattice 2014, to appear in the conference proceedings PoS(LATTICE2014), 15 pages, 9 figure

Introduction to QCD

These lectures were originally given at TASI and are directed at a level suitable for graduate students in High Energy Physics. They are intended to give an introduction to the theory and phenomenology of quantum chromodynamics (QCD), focusing on collider physics applications. The aim is to bring the reader to a level where informed decisions can be made concerning different approaches and their uncertainties. The material is divided into five main areas: 1) fundamentals, 2) fixed-order perturbative QCD, 3) Monte Carlo event generators and parton showers, 4) Matching at Leading and Next-to-Leading Order, and 5) Soft QCD physics.Comment: Lecture notes from a course given at TASI 2012. Last update: July 2017. 85 pages, including index at the back. arXiv admin note: text overlap with arXiv:1104.286

Proceedings, MSVSCC 2015

The Virginia Modeling, Analysis and Simulation Center (VMASC) of Old Dominion University hosted the 2015 Modeling, Simulation, & Visualization Student capstone Conference on April 16th. The Capstone Conference features students in Modeling and Simulation, undergraduates and graduate degree programs, and fields from many colleges and/or universities. Students present their research to an audience of fellow students, faculty, judges, and other distinguished guests. For the students, these presentations afford them the opportunity to impart their innovative research to members of the M&S community from academic, industry, and government backgrounds. Also participating in the conference are faculty and judges who have volunteered their time to impart direct support to their students’ research, facilitate the various conference tracks, serve as judges for each of the tracks, and provide overall assistance to this conference. 2015 marks the ninth year of the VMASC Capstone Conference for Modeling, Simulation and Visualization. This year our conference attracted a number of fine student written papers and presentations, resulting in a total of 51 research works that were presented. This year’s conference had record attendance thanks to the support from the various different departments at Old Dominion University, other local Universities, and the United States Military Academy, at West Point. We greatly appreciated all of the work and energy that has gone into this year’s conference, it truly was a highly collaborative effort that has resulted in a very successful symposium for the M&S community and all of those involved. Below you will find a brief summary of the best papers and best presentations with some simple statistics of the overall conference contribution. Followed by that is a table of contents that breaks down by conference track category with a copy of each included body of work. Thank you again for your time and your contribution as this conference is designed to continuously evolve and adapt to better suit the authors and M&S supporters. Dr.Yuzhong Shen Graduate Program Director, MSVE Capstone Conference Chair John ShullGraduate Student, MSVE Capstone Conference Student Chai

Investigation of Quark Gluon Plasma-like signals with Lund string interactions

This thesis investigates the interactions that occur in extreme densities for high-energy collisions of subatomic particles. The theoretical models developed for this purpose are based on the Lund model. The developments have been implemented as a new module called Gleipnir to the Monte-Carlo event generator, P YTHIA . The two models developed are string shoving and rope hadronization, and can now be used for proton-proton, proton-nucleus and nucleus-nucleus collisions.Paper I presents a novel method to calculate string shoving in all systems. The strings are considered as colour flux-tubes, with colour electric fields with transverse extent. The force between two colour flux tubes is calculated in a special Lorentz frame called the parallel frame. Final state collectivity reproduced by string shoving is investigated in both small and large systems. We conclude that further modifications to string shoving are required to be able to produce a better agreement with experimental data for large systems.Paper II presents the rope hadronization mechanism using the parallel frame. Rope hadronization would modify the strangeness yields, and this effect can be observed in jets as well. The system of interest is jet-triggered proton-proton collisions, where we probe the yields of strange hadrons and baryons in a jet. We find significant enhance-ment of strangeness, particularly strange baryons in the jet.Paper III shows the enhancement in strangeness yields with rope hadronization in all systems, using the tech-niques introduced in Paper I and Paper II. The formalism produces significant improvements over default Pythia and Angantyr. To be able to reproduce a better agreement to data, further modifications are necessary, such as the inclusion of string shoving mechanism.Paper IV describes the correction to production vertices of primary hadrons from string interactions for both small and large systems. The impact from string shoving is found to be higher than compared to rope hadronization. This would influence other P YTHIA processes that build on primary hadronic vertices such as hadronic rescattering