Download or read book Renormalization of Operators for Excited state Hadrons in Lattice QCD written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the primary aims of lattice QCD is to accurately compute the spectrum of hadronic excitations from first principles. However, obtaining an accurate resolution of excited states using methods of lattice QCD is not a trivial problem due to faster decay of excited-states correlation functions in Euclidean space in comparison to those of ground states. To overcome this difficulty, anisotropic lattices with a finer temporal discretization are used. To go beyond the spectrum, in order to study the properties of the states, one needs to compute corresponding matrix elements. Thus, for example, the quark distribution amplitudes in mesons are given by matrix elements of quark bilinear operators, while in baryons, the corresponding quark distribution amplitudes are related to matrix elements of three-quark operators. To relate the matrix elements calculated on the lattice to those in the continuum, and hence to relate to the measured experimentally, it is necessary to evaluate matching coefficients. In this work we describe the calculation of the matching coefficients using perturbation theory for the improved anisotropic-clover fermion action used for our studies of excited states.

Download or read book Formal Developments for Lattice QCD with Applications to Hadronic Systems written by Zohreh Davoudi and published by . This book was released on 2014 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to make reliable predictions with controlled uncertainties for a wide range of nuclear phenomena, a theoretical bottom-up approach, by which hadrons emerge from the underlying theory of strong interactions, quantum chromodynamics (QCD), is desired. The strongly interacting quarks and gluons at low energies are responsible for all the dynamics of nucleons and their clusters, the nuclei. The theoretical framework and the combination of analytical and numerical tools used to carry out a rigorous non-perturbative study of these systems from QCD is called lattice QCD. The result of a lattice QCD calculation corresponds to that of nature only in the limit when the volume of the spacetime is taken to infinity and the spacing between discretized points on the lattice is taken to zero. A better understanding of these discretization and volume effects, not only provides the connection to the infinite-volume continuum observables, but also leads to optimized calculations that can be performed with available computational resources. This thesis includes various formal developments in this direction, along with proposals for novel improvements, to be used in the upcoming LQCD studies of nuclear and hadronic systems. As the space(time) is discretized on a (hyper)cubic lattice in (most of) lattice QCD calculations, the lattice correlation functions are not fully rotationally invariant. This is known to lead to mixing between operators (those interpolating the states or inserting external currents) of higher dimensions with those of lower dimensions where the coefficients of latter diverge with powers of inverse lattice spacing, a, as the continuum limit is approached. This issue has long posed computational challenges in lattice spectroscopy of higher spin states, as well as in the lattice extractions of higher moments of hadron structure functions. We have shown, through analytical perturbative investigations of field theories, including QCD, on the lattice that a novel choice of operators, smeared over several lattice sites and deduced from a continuum angular momentum, has a smooth continuum limit. The scaling of the lower dimensional operators is proven to be no worse than a squared, explaining the success of recent numerical studies of excited state spectroscopy of hadrons with similar choices of operators. These results are presented in chapter 2 of this thesis. Due to Euclidean nature of lattice correlation function, the physical scattering parameters must be obtained via an analytical continuation to Minkowski spacetime. However, this continuation is practically impossible in the infinite-volume limit of lattice correlation function except at the kinematic thresholds. A formalism due to Luscher overcomes this issue by making the connection between the finite-volume spectrum of two interacting particles and their infinite-volume scattering phase shifts. We have extended the Luscher methodology, using an effective field theory approach, to the two-nucleon systems with arbitrary spin, parity and total momentum (in the limit of exact isospin symmetry) and have studied its application to the deuteron system, the lightest bound states of the nucleons, by careful analysis of the finite-volume symmetries. A proposal is presented that enables future precision lattice QCD extraction of the small D/S ratio of the deuteron that is known to be due to the action of non-central forces. By investigating another scenario, we show how significant volume improvement can be achieved in the masses of nucleons and in the binding energy of the deuteron with certain choices of boundary conditions in a lattice QCD calculation of these quantities. These results are discussed in chapters 3, 4 and 5. In order to account for electromagnetic effects in hadronic systems, lattice QCD calculations have started to include quantum electrodynamic (QED). These effects are particularly interesting in studies of mass splittings between charged and neutral members of isospin multiplets, e.g. neutral and charged pions. Due to the infinite range of QED interactions large volume effects plaque these studies. Using a non-relativistic effective theory for electromagnetic interactions of hadrons, we analytically calculate, and numerically estimate, the first few finite-volume corrections (up to 1 over L to the 4th power where L is the spatial extent of the volume) to the masses of hadrons and nuclei at leading order in the QED coupling constant, but to all orders in the short-distance strong interaction effects. These results are presented in chapter 6.

Download or read book Hadronic Physics from Lattice QCD written by Anthony M. Green and published by World Scientific. This book was released on 2004 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particle and nuclear physicists frequently take results from Lattice QCD at their face value without probing into their reliability or sophistication. This attitude usually stems from a lack of knowledge of the field. The aim of the present volume is to rectify this by introducing in an elementary way several topics, which we believe are appropriate for, and of possible interest to, both particle and nuclear physicists who are non-experts in the field.

Download or read book From Parity Violation to Hadronic Structure and more written by Serge Kox and published by Springer Science & Business Media. This book was released on 2007-06-07 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Almost 50 years after the proposal of Lee and Young in 1956 to test the hypothesis of parity violation in weak interactions and the subsequent experimental verification of parity violation by C. S. Wu, parity violation has today become a useful property of weak interactions. This is due to the fact that the focus nowadays has changed: parity violation in weak interactions is no more a topic of investigation but is used as a tool in many different fields ranging from nuclear physics to the search for the hidden extra dimensions requested by string theory. For our first workshop which took place June 5-8, 2002, at the Institut fiir Ke- physik of the Johannes Gutenberg-Universitat Mainz, we concentrated on the in vestigation of the strangeness contribution in the nucleon. This book contains the refereed and selected papers of the second workshop "From Parity Violation to Hadron Structure and more (Part II)", which took place June 8-11, in the Labo- toire de Physique Subatomique et de Cosmologie, in Grenoble. These papers appear in EPJAdirect, the electronic-only part of EPJA, and they are accessible without restrictions. They will also appear in printed form and can be ordered through Springer. The excellent presentations show the dramatic and steady progress in the accuracy of measured parity violating asymmetries over the last few years.

Download or read book Particle Physics Reference Library written by Herwig Schopper and published by Springer Nature. This book was released on 2020 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Exact Renormalization Group The Proceedings Of The Workshop written by Alexander Krasnitz and published by World Scientific. This book was released on 1999-08-13 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject of the exact renormalization group started from pioneering work by Wegner and Houghton in the early seventies and, a decade later, by Polchinski, who formulated the Wilson renormalization group for field theory. In the past decade considerable progress has been made in this field, which includes the development of alternative formulations of the approach and of powerful techniques for solving the exact renormalization group equations, as well as widening of the scope of the exact renormalization group method to include fermions and gauge fields. In particular, two very recent results, namely the manifestly gauge-invariant formulation of the exact renormalization group equation and the proof of the c-theorem in four dimensions, are presented in this volume.

Download or read book Perturbative Renormalization of Proton Observables in Lattice QCD Using Domain Wall Fermions written by Bojan Bistrović and published by . This book was released on 2005 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep inelastic scattering unambiguously measures hadron observables characterizing the quark-gluon structure of hadrons. The only way to calculate these observables from first principles is lattice QCD. Experiments measure matrix elements of light cone operators ... where diagonal elements specify the quark density distribution q(x), quark helicity distribution [delta] q(x) and quark transversity distribution [delta] q(x). Off-diagonal elements determine form factors and general parton distributions. Due to the Minkowskian nature of these matrix elements, they cannot be evaluated on a Euclidean lattice so one uses the operator product expansion to calculate matrix elements ... which specify moments of these distributions. In this thesis, renormalization factors have been calculated for local bilinear operators of the form ... in a given irreducible representation of hypercubic group as well as mixing coefficients of those operators for low moments of physical interest. In the past, it was only possible to calculate with quark masses such that ... Now for the first time using Ginsparg-Wilson "Domain Wall" fermions with HYP smearing and full QCD configurations on large lattices make calculations possible in the physical chiral regime.

Download or read book Theory Of Hadrons And Light Front Qcd Proceedings Of The Fourth International Workshop On Light front Quantization And Non perturbative Dynamics written by S D Glazek and published by World Scientific. This book was released on 1995-04-26 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume includes 45 talks and reports from facilitated discussions by outstanding contributors to the theory of hadrons that cover the entire spectrum of computational strategies being developed to solve QCD.A new computational strategy for solving light-front QCD, a strategy which starts with a constituent quark model that can be solved using the weak-coupling methods of QED, is extensively reviewed.

Download or read book Perturbative Renormalization of Proton Observables in Lattice QCD Using Domain Wall Fermions written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep inelastic scattering unambiguously measures hadron observables characterizing the quark-gluon structure of hadrons. The only way to calculate these observables from first principles is lattice QCD. Experiments measure matrix elements of light cone operators ... where diagonal elements specify the quark density distribution q(x), quark helicity distribution [delta] q(x) and quark transversity distribution [delta] q(x). Off-diagonal elements determine form factors and general parton distributions. Due to the Minkowskian nature of these matrix elements, they cannot be evaluated on a Euclidean lattice so one uses the operator product expansion to calculate matrix elements ... which specify moments of these distributions. In this thesis, renormalization factors have been calculated for local bilinear operators of the form ... in a given irreducible representation of hypercubic group as well as mixing coefficients of those operators for low moments of physical interest. In the past, it was only possible to calculate with quark masses such that ... Now for the first time using Ginsparg-Wilson "Domain Wall" fermions with HYP smearing and full QCD configurations on large lattices make calculations possible in the physical chiral regime.

Download or read book On the Renormalization and Short Distance Properties of Hadronic Operators in QCD written by N. S. Craigie and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics in Collision 14 written by Stephen Keller and published by Atlantica Séguier Frontières. This book was released on 1995 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Composite Operators in Lattice QCD written by and published by . This book was released on 1998 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1992 with total page 710 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heavy Quark Physics written by Aneesh V. Manohar and published by Cambridge University Press. This book was released on 2023-07-31 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quantum Chromodynamics written by Walter Greiner and published by Springer Science & Business Media. This book was released on 2011-06-28 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum Chromodynamics is a thorough introduction for students in theoretical physics and scientists needing a reference and exercise book in this field. The book presents the necessary mathematical tools together with many examples and worked problems. In introductory chapters the reader becomes familiar with the hadron spectrum, while the SU(N) symmetry groups and the relativistic field theory are briefly recapitulated; then a discussion of scalar quantum electrodynamics and scattering reactions follow before gauge quark-quark interactions, perturbational QCD, renormalization groups, and tests of pertubational QCD are all treated in detail. Chapters on non-perturbational QCD and quasi-phenomenological applications conclude the text.

Download or read book Unfolding the Matter of Nuclei written by Società italiana di fisica and published by IOS Press. This book was released on 1998 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nucleus and its constituents are a challenging problem. The lectures collected in this book present a broad and comprehensive review of the current knowledge about nuclei.They cover topics such as searching for signatures of the quarks in nuclei with electromagnetic probes and, at much higher energies, for signatures of the quark-gluon plasma in ultrarelativistic nuclear collisions. The attempts to obtain new nuclei in the laboratory are also discussed, as well as the central role played by nuclear physics in the development of weak interactions. Progress in all these areas rests on a deeper theoretical handling of the nuclear and nucleon’s structure. The latter can also be addressed by relying on numerical solutions of QCD on a discrete space-time lattice. The advancement of computational capabilities has spurred a growing interest in this approach. Finally, the book deals with different paths toward solving non-perturbative QCD.

Download or read book Studies in Hadron Structure Using Lattice QCD with Quark Masses that Almost Reach the Physical Point written by Jeremy Russell Green and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lattice QCD allows us to study the structure of hadrons from first-principles calculations of quantum chromodynamics. We present calculations that shed light on the behavior of quarks inside hadrons in both qualitative and quantitative ways. The first is a study of diquarks. We bind two quarks in a baryon with a static quark and compute the simultaneous two-quark density, including corrections for periodic boundary conditions. Defining a correlation function to isolate the intrinsic correlations of the diquark, we find that away from the immediate vicinity of the static quark, the diquark has a consistent shape, with much stronger correlations seen in the scalar diquark than in the axial-vector diquark. We present results at pion masses 293 and 940 MeV and discuss the dependence on the pion mass. The second set of calculations is a more quantitative study that covers a wide range of (mainly isovector) nucleon observables, including the Dirac and Pauli radii, the magnetic moment, the axial charge, and the average quark momentum fraction. Two major advances over previous calculations are the use of a near-physical pion mass, which nearly eliminates the uncertainty associated with extrapolation to the physical point, and the control over systematic errors caused by excited states, which is a significant focus of this thesis. Using pion masses as low as 149 MeV and spatial box sizes as large as 5.6 fm, we show the importance of good control over excited states for obtaining successful postdictions -- which we achieve for several quantities -- and we identify a remaining source of systematic error that is likely responsible for disagreement with experiment in the axial sector. We then use this understanding of systematics to make predictions for observables that have not been measured experimentally.