Wilson Twisted Mass Fermions: Towards Realistic Simulations of Lattice QCD PDF Download

Author: Carsten Urbach
Publisher:
ISBN:
Category :
Languages : en
Pages : 132

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Author: Jackson M. S. Wu
Publisher:
ISBN:
Category : Lattice field theory
Languages : en
Pages : 182

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Author: Thomas DeGrand
Publisher: World Scientific
ISBN: 9812773983
Category : Science
Languages : en
Pages : 363

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Book Description
At a time of robust worldwide debates on globalization, this compact volume shows: how successful each of the East Asian economies have been in harnessing globalization by appropriate and alternative means to catch up with the advanced economies; and what implications can be drawn to assess Chinese economic growth in context. The essays in this book include supporting notes to review effectively the highlights of the development of East Asia, over the six decades after World War II: why the region has performed so well economically relative to the rest of the developing world; which are the most challenging limitations to be addressed; and several sensational controversies in the development economics literature to be sensibly resolved.

Author: Derek P. Horkel
Publisher:
ISBN:
Category : Lattice gauge theories
Languages : en
Pages : 141

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Book Description
In this thesis we describe two studies concerting lattice quantum chromodynamics (LQCD): first, an analysis of the phase structure of Wilson and twisted-mass fermions with isospin breaking effects, second a computational study measuring non-perturbative Greens functions. We open with a brief overview of the formalism of QCD and LQCD, focusing on the aspects necessary for understanding how a lattice computation is performed and how discretization effects can be understood. Our work in Wilson and twisted-mass fermions investigates an increasingly relevant regime where lattice simulations are performed with quarks at or near their physical masses and both the mass difference of the up and down quarks and their dif- fering electric charges are included. Our computation of a non-perturbative Greens functions on the lattice serves as a first attempt to validate recent work by Dine et. al. [24] in which they calculate Greens functions which vanish in perturbation theory, yet have a contribution from the one instanton background. In chapter 2, we determine the phase diagram and pion spectrum for Wilson and twisted- mass fermions in the presence of non-degeneracy between the up and down quark and dis- cretization errors, using Wilson and twisted-mass chiral perturbation theory. We find that the CP-violating phase of the continuum theory (which occurs for sufficiently large non- degeneracy) is continuously connected to the Aoki phase of the lattice theory with degen- erate quarks. We show that discretization effects can, in some cases, push simulations with physical masses closer to either the CP-violating phase or another phase not present in the continuum, so that at sufficiently large lattice spacings physical-point simulations could lie in one of these phases. In chapter 3, we extend the work in chapter 2 to include the effects of electromag- netism, so that it is applicable to recent simulations incorporating all sources of isospin breaking. For Wilson fermions, we find that the phase diagram is unaffected by the inclu- sion of electromagnetism--the only effect is to raise the charged pion masses. For maximally twisted fermions, we previously took the twist and isospin-breaking directions to be different, in order that the fermion determinant is real and positive. However, this is incompatible with electromagnetic gauge invariance, and so here we take the twist to be in the isospin-breaking direction, following the RM123 collaboration. We map out the phase diagram in this case, which has not previously been studied. The results differ from those obtained with different twist and isospin directions. One practical issue when including electromagnetism is that the critical masses for up and down quarks differ. We show that one of the criteria suggested to determine these critical masses does not work, and propose an alternative. In chapter 4, we delve deeper into the technical details of the analysis in chapter 3. We determine the phase diagram and chiral condensate for lattice QCD with two flavors of twisted-mass fermions in the presence of nondegenerate up and down quarks, discretization errors and a nonzero value of [Theta]QCD. We find that, in general, the only phase structure is a first-order transition of finite length. Pion masses are nonvanishing throughout the phase plane except at the endpoints of the first-order line. Only for extremal values of the twist angle and [Theta]QCD ([omega] = 0 or [pi]/2 and [Theta]QCD = 0 or [pi]) are there second-order transitions. In chapter 5 we move on to a new topic, working to make a first measurement of non- perturbative Greens functions which vanish in perturbation theory but have a non-vanishing one-instanton contribution, as suggested in recent work by Dine et. al. [24] using a semi- classical approach. This measurement was done using 163 × 48 configurations generated by the MILC collaboration, with coupling [Beta] = 6.572, light quark mass mla = 0.0097, strange quark mass msa = 0.0484, lattice spacing a ≈ 0.14 fm and pion mass m[pi]a = 0.2456. The analysis was done by separating the Green function of interest into pseudoscalar and scalar components. These are separately calculated on 440 configurations, using the Chroma software package. To improve statistics, we used the various reduction technique suggested in Ref. [13]. We subtracted out the long distance contributions from the pion, excited pion and a0 from the Green function, in the hope of obtaining the short distance form predicted by Ref. [24]. Unfortunately, after subtraction of the a0 and pion states only noise remained. While the results are not in themselves useful, we believe this approach will be worth repeating in the future with finer lattices with a fermion action with better chiral symmetry.

Author: Laurent Lellouch
Publisher: Oxford University Press
ISBN: 0199691606
Category : Mathematics
Languages : en
Pages : 756

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Book Description
The aim of the book is to familiarize the new generation of PhD students and postdoctoral fellows with the principles and methods of modern lattice field theory, which aims to resolve fundamental, non-perturbative questions about QCD without uncontrolled approximations.

Author: Christof Gattringer
Publisher: Springer
ISBN: 3642018505
Category : Science
Languages : en
Pages : 352

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Book Description
This introduction to quantum chromodynamics presents the basic concepts and calculations in a clear and didactic style accessible to those new to the field. Readers will find useful methods for obtaining numerical results, including pure gauge theory and quenched spectroscopy.

Author: Ernst-Michael Ilgenfritz
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Herwig Schopper
Publisher: Springer Nature
ISBN: 3030382079
Category : Heavy ions
Languages : en
Pages : 632

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Book Description
This first open access volume of the handbook series contains articles on the standard model of particle physics, both from the theoretical and experimental perspective. It also covers related topics, such as heavy-ion physics, neutrino physics and searches for new physics beyond the standard model. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access

Author: Antonio Dobado
Publisher: Springer Science & Business Media
ISBN: 3540725164
Category : Science
Languages : en
Pages : 615

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Book Description
The QNP series of international conferences on Quarks and Nuclear Physics is by now a well established and highly respected forum where the most recent developments in the field are discussed and communicated. QNP 2006 is the forth edition of this biennial meeting. Selected and refereed original contributions of QNP 2006 have been published in The European Physical Journal A - Hadrons and Nuclei (EPJ A), while the present proceedings book, in addition to reprinting the articles published in EPJ A, further includes all other contributions selected and accepted by the organizing committee for publication and archiving.

Author: Koichi Yamawaki
Publisher: World Scientific
ISBN: 9814475475
Category : Science
Languages : en
Pages : 439

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Book Description
This volume includes discussion on new dynamical features in the light of (deconstruted/latticized) extra dimensions, holographic QCD, Moose/hidden local symmetry, and so on. New insights into the QCD as a prototype of strong coupling gauge theories as well as in its own right, particularly in hot and dense matter are included.