Download or read book Pion and Rho structure Functions from Lattice QCD written by and published by . This book was released on 1997 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lattice QCD at the Physical Point written by Thibaut Métivet and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The formalism of Quantum Chromodynamics on the lattice (or Lattice QCD) allows to perform ab-initio non-perturbative studies of strong-interaction driven processes, as it provides both a covariant regularisation of the theory of QCD and a natural framework for numerical computations. In this work, after a review of the main features of QCD and a step-by-step presentation of our discretization of QCD on a lattice, we undertake detailed studies of two problems of hadronic physics: the phenomenon of resonant scattering and the structure of the nucleon. The lattice calculations are performed with the Budapest-Marseille-Wuppertal Collaboration's 2+1-flavour gauge configurations, which give access to a wide range of lattice spacings, volumes and quarks masses, thereby allowing to study the sensibility of our results on these parameters, and to perform a complete continuum extrapolation. These configurations include dynamical quarks, and use a clover-improved Wilson QCD action. To investigate the scattering of particles on the lattice, we set up a Lüscher analysis for the emblematic case of pion-pion scattering in the channel of the rho meson resonance. We analyse our data with a variational generalized eigenvalue method, and give an in-depth calculation of the scattering phase-shifts and the corresponding resonance parameters, with a full control of the systematic errors. Our results provide an important step for lattice studies of scattering states, as they are the first to be performed at the physical pion mass, where one can see the actual decay of the rho into two pions. The obtained rho meson parameters are in good agreement with the experimental values, and consistent with a weak pion mass dependence of the coupling between the rho and two pions. As for our probe of the structure of the nucleon, we present a complete extraction of the electroweak isovector form factors, with a comprehensive study of the electric charge squared radius and of the axial charge. Our analysis also feature data at the physical pion mass, which turns out to be crucial in order to perform safe extrapolations to the physical point, as the chiral perturbation theory predicts violent variations of these quantities near the massless-quarks point. Our calculation includes source and sink projections onto the nucleon state, as well as a combined fit method between the two-point and three-point correlation functions to control the contamination of our data by excited states. Although one would need more data to perform a high-accuracy determination of the nucleon radius and axial charge at the physical point with a relevant estimation of the systematic errors, the results we obtain are in good agreement with the experiment and suggest that the excited-state effects are under control. Our analysis also highlights that gauge configurations ensembles near the physical pion mass and with large volumes must be used in order to extract accurate information about the nucleon structure from lattice calculations.
Download or read book Spin Structure of the Nucleon written by Erhard Steffens and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive survey of the most recent results from the field of quark-gluon structure of the nucleon, in particular how the spin of the nucleon is shared by its constituents. After very intriguing results from CERN and SLAC at the end of the 1980s, the last decade has seen a set of second-generation experiments at high energy accelerators that have yielded precise information on the solution of the 'Spin Crisis' - as well as opening up new questions. The articles are written by experts from the leading collaboration and theory groups as well as providing an expert summary of the state of the art, the book points the way to future research directions. Its main focus is on semi-inclusive and exclusive measurements of deep inelastic lepton scattering, which enables for the first time the determination of the flavor-separated quark spin distributions. Future developments on generalized parton distributions and their interpretation as well as the transverse spin structure are also covered. An indispensable volume for all working in hadronic physics.
Download or read book Lepton Scattering Hadrons And Qcd Procs Of The Workshop written by W Melnitchouk and published by World Scientific. This book was released on 2001-10-19 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is centered on recent developments in the exploration of hadronic structure through lepton scattering, in the description of hadron physics directly from lattice QCD and non-perturbative QCD models, and in efforts to strengthen the links between these activities. Specific topics that are covered include: parton distribution functions, polarized structure functions, generalized structure functions, nuclear effects, quark-hadron duality, electromagnetic form factors, structure functions and hadron properties from lattice QCD, and QCD models based on the Dyson-Schwinger equations.
Download or read book Pion Structure Form Lattice QCD written by and published by . This book was released on 2015 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structure of the Pion from Full Lattice QCD written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pion Parton Distribution Functions from Lattice QCD written by and published by . This book was released on 2003 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Lattice QCD Study of the Rho Resonance and the Timelike Pion Form Factor written by Felix Benjamin Erben and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hadron Physics written by I.J. Douglas MacGregor and published by CRC Press. This book was released on 2006-07-07 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Straddling the traditional disciplines of nuclear and particle physics, hadron physics is a vital and extremely active research area, as evidenced by a 2004 Nobel prize and new research facilities, such as that scheduled to open at CERN. Scientifically it is of vital importance in extrapolating our knowledge of quark-gluon physics at the sub-nucleon level to provide a wider perspective of strongly interacting hadrons, which make up the vast bulk of known matter in the Universe. Through detailed, pedagogical chapters contributed by key international experts, Hadron Physics maps out our contemporary knowledge of the subject. It covers both the theoretical and experimental aspects of hadron structure and properties along with a wide range of specific research topics, results, and applications. Providing a full picture of activity in the field, the book highlights three particular areas of current research: computational lattice hadron physics, the structure and dynamics of hadrons, and generalized parton distributions. It provides a solid introduction, includes background theory, and presents the current state of understanding of the subject.
Download or read book Lattice written by and published by . This book was released on 2003 with total page 1134 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Pion Form Factor in Lattice QCD written by Draper, Terrence and published by . This book was released on 1988 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pion Spectral Properties Above the Chiral Crossover of QCD written by Peter Lowdon and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectral functions encode a wealth of information about the dynamics of any given system, and the determination of their non-perturbative characteristics is a long-standing problem in quantum field theory. Whilst numerical simulations of lattice QCD provide ample data for various Euclidean correlation functions, the inversion required to extract spectral functions is an ill-posed problem. In this work, we pursue previously established constraints imposed by field locality at finite temperature T, namely that spectral functions possess a non-perturbative representation which generalises the well-known Källén-Lehmann spectral form to T > 0. Using this representation, we analyse lattice QCD data of the spatial pseudo-scalar correlator in the temperature range 220-960 MeV, and obtain an analytic expression for the corresponding spectral function, with parameters fixed by the data. From the structure of this spectral function we find evidence for the existence of a distinct pion state above the chiral pseudo-critical temperature Tpc, and contributions from its first excitation, which gradually melt as the temperature increases. As a non-trivial test, we find that the extracted spectral function reproduces the corresponding temporal lattice correlator data for T = 220 MeV.
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 Generalized Parton Distributions and Structure Functions from Full Lattice QCD written by and published by . This book was released on 2004 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Improved Pion Correlation Functions Under Lattice Action written by Daniel Hoying and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the first calculation of pion-pion ($\pi\pi$) scattering at physical quark mass from lattice QCD. We simulate QCD in a periodic $\sim 5$ fm box at inverse lattice spacing $a^{-1}=1.015,1.3784$ GeV using zM\"obius/M\"obius Domain Wall Fermions and Iwasaki Gauge Action. We form operators composed of localized hydrogen-like wave functions for scalar ($\overline{\psi}\psi$), pseudoscalar ($\overline{\psi}\gamma_5\psi$), and vector bilinears ($\overline{\psi}\gamma_\mu\psi$) We then calculate all-to-all (A2A) meson field propagators for up to three units of individual particle momenta as well as isospin $I=0,1,2$, with up to (in the $I=0,2$) three units of center of mass momentum. This allows us to project the resulting $O(10000)$ correlation functions onto definite isospin and irreducible representation (which allows us to project onto the lowest bose-symmetry allowed angular momenta of each of our operators). These projections form correlation function matrices of definite time separation, which then naturally define a generalized eigenvalue problem (GEVP) we can solve for the desired spectra. We then apply the L\"uscher method to obtain from our lattice energies continuum scattering phase shifts. After partially accounting for some of our systematic errors, we obtain fair to good agreement with phenomenological predictions for the phase shifts as derived from Roy equations and chiral perturbation theory. These results can help serve as a foundation on which to build a fully periodic calculation of a kaon decaying into two pions ($K\to\pi\pi)$, a very important decay related to the study of baryogenesis in the Standard Model. This work also contains algorithmic and mathematical developments which, while not used directly in the $\pi\pi$ scattering study, are likely to be useful in the study of $K\to\pi\pi$ (and might also be useful to interaction physics generally). These developments are highlighted briefly in the introduction.
Download or read book Higher Twist Corrections to Nucleon Structure Functions from Lattice QCD written by and published by . This book was released on 1999 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
