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Insight Into Nucleon Structure From Generalized Parton Distributions
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Book Synopsis Insight Into Nucleon Structure from Generalized Parton Distributions by : R. Edwards
Download or read book Insight Into Nucleon Structure from Generalized Parton Distributions written by R. Edwards and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The lowest three moments of generalized parton distributions are calculated in full QCD and provide new insight into the behavior of nucleon electromagnetic form factors, the origin of the nucleon spin, and the transverse structure of the nucleon.
Book Synopsis Insight Into Nucleon Structure from Lattice Calculations of Moments of Parton and Generalized Parton Distributions by :
Download or read book Insight Into Nucleon Structure from Lattice Calculations of Moments of Parton and Generalized Parton Distributions written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This talk presents recent calculations in full QCD of the lowest three moments of generalized parton distributions and the insight they provide into the behavior of nucleon electromagnetic form factors, the origin of the nucleon spin, and the transverse structure of the nucleon. In addition, new exploratory calculations in the chiral regime of full QCD are discussed.
Book Synopsis Nucleon Structure and Generalized Parton Distributions by : Eric Voutier
Download or read book Nucleon Structure and Generalized Parton Distributions written by Eric Voutier and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses a selected part of the experimental program dedicated to the study of Generalized Parton Distributions, a recently introduced concept which provides a comprehensive framework for investigations of the partonic structure of the nucleon. Particular emphasis is put on the Deeply Virtual Compton Scattering program performed at the Jefferson Laboratory. The short and long term future of this program is also discussed in the context of the several experimental efforts aiming at a complete and exhaustive mapping of Generalized Parton Distributions.
Book Synopsis Generalized Parton Distributions and the Structure of the Nucleon by :
Download or read book Generalized Parton Distributions and the Structure of the Nucleon written by and published by . This book was released on 2007 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Nucleon Structure from Generalized Parton Distributions in Lattice QCD by :
Download or read book Nucleon Structure from Generalized Parton Distributions in Lattice QCD written by and published by . This book was released on 2005 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions by : Kemal Tezgin
Download or read book Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions written by Kemal Tezgin and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The understanding of the internal structure of the proton and other strongly interacting particles is at the forefront of modern nuclear physics research. Generalized Parton Distribution Functions (GPDs) are a powerful tool to advance the understanding of hadron structure. In addition to the information about the one- dimensional collinear momentum distributions of partons (quarks, anti-quarks, and gluons) known from studies of high energy deep-inelastic reactions, GPDs also carry information on the distribution of partons in the transverse plane, and allow us in this way to access the three-dimensional structure of the nucleon. GPDs can be studied in hard-exclusive reactions and contain also information on the energy-momentum tensor form factors which will allow us to gain insights on quantities like pressure or angular momentum distribution inside the nucleon. The goal of this thesis is to deepen our understanding of the three-dimensional structure of the nucleon. We investigate energy-momentum tensor form factors and densities, and all leading-twist GPDs in the bag model. This quark model provides a consistent theoretical framework to investigate many general concepts that have recently attracted interest, and allows one to study insightful limits like the large-Nc limit, heavy-quark limit or the non-relativistic limit. Another important aspect of this thesis is the discussion of the monopole and quadrupole contributions to the angular momentum density. Finally, the description of pseudoscalar meson production in exclusive processes in terms of GPDs is discussed in the Goloskokov-Kroll model and implemented in the PARTONS framework, a software development project which will provide direct support for experiments at the Jefferson National Lab and the future Electron-Ion Collider.
Book Synopsis Generalized Parton Distributions and Their Covariant Extension by : Nabil Chouika
Download or read book Generalized Parton Distributions and Their Covariant Extension written by Nabil Chouika and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Generalized Parton Distributions (GPDs) encode the correlations between longitudinal momentum and transverse position of partons inside hadrons and can give access to a picture of the nucleon structure in 2+1 dimensions. They have been studied theoretically and experimentally for almost two decades and a new experimental era is starting (at JLab and COMPASS currently, and in the future at an EIC) to extract them. The difficulty is that only an indirect experimental access is so far possible, through different exclusive channels and various observables. Therefore, one has to take into account the many theoretical constraints to be able to produce accurate models and rely on their phenomenology. Two important constraints are called the polynomiality and positivity properties. The approach of this thesis is to make use of both of them by first modeling low Fock states light-front wave-functions, which gives a GPD in the DGLAP region by a parton number conserved overlap, and then covariantly extending this GPD to the ERBL region, through an inverse radon transform. In fine, the goal is to apply this on a constituent quark-like model for valence GPDs, which would allow to produce a phenomenological output (on DVCS data for instance) from this kind of models, which was impossible before. We make use of the versatile PARTONS framework to achieve this under various perturbative QCD assumptions.
Book Synopsis Spin Structure of the Nucleon by : Erhard Steffens
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.
Book Synopsis Nucleon Structure from Stochastic Estimators by : Johannes Siegfried Samir Najjar
Download or read book Nucleon Structure from Stochastic Estimators written by Johannes Siegfried Samir Najjar and published by Universitatsverlag Regensburg. This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of the proton and neutron, parameterized by moments of generalized parton distribution functions (GPDs), can be accessed from first principle through the computation of baryon three-point functions with lattice QCD. The numerical effort involved in such computations is quite high and thus an efficient algorithm that extracts most information at given cost is highly desirable. In this work we demonstrate that stochastic estimation techniques can efficiently increase the information/cost ratio. We examine the available results at $N_f=2$ for the nucleon axial coupling $g_A$ and iso-vector quark momentum fraction $\langle x \rangle _{u-d}$ from various collaborations and compare them to the experimental values. The tension between them is attributed to excited state contributions (ESC). We furthermore study the impact of this ESC in moments of GPDs through a model fit. This model also deals with the effects of the choice of parameters used in the computation, like the source-sink separation $t_{\mathrm{sink}}$. We demonstrate that the choice of $t_{\mathrm{sink}}$ by the Regensburg group in previous studies was reasonable and cannot account for discrepancies with the experiment. To reduce the excited state contributions in two-point functions, and consequently three-point functions, we suggest a non-Gaussian quark smearing. This is a linear combination of two Gaussian smearings with one free parameter, which can be tuned to an optimal choice with a fit.
Book Synopsis Structure and Spin of the Nucleon by :
Download or read book Structure and Spin of the Nucleon written by and published by . This book was released on 2014 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
Book Synopsis Generalized Parton Distributions in Nuclei by : Swadhin k Taneja
Download or read book Generalized Parton Distributions in Nuclei written by Swadhin k Taneja and published by . This book was released on 2006 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Generalized Parton Distributions and Angular Momentum Decomposition of the Nucleon by : Hikmat Bahadur BC
Download or read book Generalized Parton Distributions and Angular Momentum Decomposition of the Nucleon written by Hikmat Bahadur BC and published by . This book was released on 2010 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A COMPREHENSIVE STUDY OF THE PROTON STRUCTURE by : Shohini Bhattacharya
Download or read book A COMPREHENSIVE STUDY OF THE PROTON STRUCTURE written by Shohini Bhattacharya and published by . This book was released on 2021 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been known since the 1930's that protons and neutrons, collectively called as nucleons, are not "point-like" elementary particles, but rather have a substructure. Today, we know from Quantum Chromodynamics (QCD) that nucleons are made from quarks and gluons, with gluons being the elementary force carriers for strong interactions. Quarks and gluons are collectively called as partons. The substructure of the nucleons can be described in terms of parton correlation functions such as Form Factors, (1D) Parton Distribution Functions (PDFs) and their 3D generalizations in terms of Transverse Momentum-dependent parton Distributions (TMDs) and Generalized Parton Distributions (GPDs). All these functions can be derived from the even more general Generalized Transverse Momentum-dependent Distributions (GTMDs). This dissertation promises to provide an insight into all these functions from the point of view of their accessibility in experiments, from model calculations, and from their direct calculation within lattice formulations of QCD. In the first part of this dissertation, we identify physical processes to access GTMDs. By considering the exclusive double Drell-Yan process, we demonstrate, for the very first time, that quark GTMDs can be measured. We also show that exclusive double-quarkonium production in nucleon-nucleon collisions is a direct probe of gluon GTMDs. In the second part of this dissertation, we shift our focus to the "parton quasi-distributions". Over the last few decades, lattice QCD extraction of the full x-dependence of the parton distributions has always been prohibited by the explicit time-dependence of the correlation functions. In 2013, there was a path-breaking proposal by X. Ji to calculate instead parton quasi-distributions (quasi-PDFs). The procedure of "matching" is a crucial ingredient in the lattice QCD extraction of parton distributions from the quasi-PDF approach. We address the matching for the twist-3 PDFs gT (x), e(x), and hL(x) for the very first time. We pay special attention to the challenges involved in the calculations due to the presence of singular zero-mode contributions. We also present the first-ever lattice QCD results for gT (x) and hL(x) and we discuss the impact of these results on the phenomenology. Next, we explore the general features of quasi-GPDs and quasi-PDFs in diquark spectator models. Furthermore, we address the Burkhardt-Cottingham-type sum rules for the relevant light-cone PDFs and quasi-PDFs in a model-independent manner and also check them explicitly in perturbative model calculations. The last part of this dissertation focuses on the extraction g1T (x,~k2â„) TMD for the very first time from experimental data using Monte Carlo techniques. This dissertation therefore unravels different aspects of the distribution functions from varied perspectives.
Book Synopsis Transverse Parton Structure of the Nucleon and the Black-disk Limit in High-energy Scattering by :
Download or read book Transverse Parton Structure of the Nucleon and the Black-disk Limit in High-energy Scattering written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The transverse spatial distribution of partons in the nucleon (generalized parton distributions) is a crucial ingredient in the description of high-energy ep and pp scattering with hard QCD processes. Experimental information about the transverse spatial distribution of gluons comes from measurements of the t-dependence of J/psi production at HERA and other processes. We discuss the physical mechanisms leading to a growth of the nucleon's transverse size at small x. Based on this information, we study the interaction of small-size color dipoles with the proton in the leading log Q2 approximation. We find that at small x and central impact parameters the dipole-nucleon interaction approaches the unitarity, or black-disk (BDL) limit. We argue that this new regime of strong interactions can be probed in central pp collisions at LHC.
Book Synopsis Nucleon Structure from Lattice QCD. by :
Download or read book Nucleon Structure from Lattice QCD. written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent advances in lattice field theory, in computer technology and in chiral perturbation theory have enabled lattice QCD to emerge as a powerful quantitative tool in understanding hadron structure. I describe recent progress in the computation of the nucleon form factors and moments of parton distribution functions, before proceeding to describe lattice studies of the Generalized Parton Distributions (GPDs). In particular, I show how lattice studies of GPDs contribute to building a three-dimensional picture of the proton, I conclude by describing the prospects for studying the structure of resonances from lattice QCD.
Book Synopsis Nucleon Form Factors from Generalized Parton Distributions by :
Download or read book Nucleon Form Factors from Generalized Parton Distributions written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We discuss the links between Generalized Parton Distributions (GPDs) and elastic nucleon form factors. These links, in the form of sum rules, represent powerful constraints on parameterizations of GPDs. A Regge parameterization for GPDs at small momentum transfer, is extended to the large momentum transfer region and it is found to describe the basic features of proton and neutron electromagnetic form factor data. This parameterization is used to estimate the quark contribution to the nucleon spin.
Book Synopsis Exploring Proton Structure Using Lattice QCD by : Dru Bryant Renner
Download or read book Exploring Proton Structure Using Lattice QCD written by Dru Bryant Renner and published by . This book was released on 2004 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: We calculate moments of the generalized parton distributions of the nucleon using lattice QCD. The generalized parton distributions determine the angular momentum decomposition of the nucleon and the transverse distributions of partons within the nucleon. Additionally, the generalized parton distributions reduce to the elastic form factors and ordinary parton distributions in particular kinematic limits. Thus by calculating moments of the generalized parton distributions in lattice QCD we can explore many facets of the structure of the nucleon. In this effort, we have developed the building block method to determine all the lattice correlation functions which con- tribute to the off forward matrix elements of the twist two operators. These matrix elements determine the generalized form factors of the nucleon which in turn give the moments of the generalized parton distributions. Thus we use our building block method to calculate all the matrix elements of the lowest twist two operators. Fur- thermore, we use our method to construct an overdetermined set of matrix elements allowing a more accurate calculation of the generalized form factors.
