Download or read book New Results on Nucleon Resonance Transition Form Factors written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent measurements with CLAS at Jefferson Lab of nucleon resonance transition form factors for several lower mass states are discussed.
Download or read book Nucleon Resonance Transition Form Factors written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We discuss recent results from CLAS on electromagnetic resonance transition amplitudes and their dependence on the distance scale (Q2). From the comparison of these results with most advanced theoretical calculations within QCD-based approaches there is clear evidence that meson-baryon contributions are present and important at large distances, i.e. small Q2, and that quark core contributions dominate the short distance behavior.
Download or read book Electromagnetic Transition Form Factors of Nucleon Resonances written by and published by . This book was released on 2008 with total page 90701 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are discussed. The new data resolve a long-standing puzzle of the nature of the Roper resonance, and confirm the assertion of the symmetric constituent quark model of the Roper as the first radial excitation of the nucleon. The data on $n\pi^+$ production at high $Q^2$ confirm the slow fall off of the $S_{11}(1535)$ transition form factor with $Q^2$, and better constrain the branching ratios $\beta_{N\pi}=0.50$ and $\beta_{N\eta}=0.45$. Also, new results on the transition amplitudes for the $D_{13}(1520)$ resonance are presented showing a rapid change from helicity 3/2 dominance seen at the real photon point to helicty 1/2 dominance at higher $Q^2$.
Download or read book Nucleon Transition Form Factors and New Perspectives written by and published by . This book was released on 2007 with total page 12012 pages. Available in PDF, EPUB and Kindle. Book excerpt: The status of the electro-excitation program to study baryon resonances at Jefferson Lab will be exemplified by the most recent results on resonance parameters and transition form factors in single and double-pion production. These results demonstrate that the separation of resonance and background contributions and therefore the extraction of the electro-coupling amplitudes of resonances become easier and cleaner at higher four-momentum transfers (Q2). Furthermore, the double-pion in comparison to the single-pion channel shows a higher sensitivity to higher excited resonances and a distinctly different Q2 dependence of the background amplitudes. The combined analysis of the single- and double-pion data reduces model dependent uncertainties significantly, which allows us to extract the resonant electrocoupling amplitudes with an unprecedented quality.
Download or read book New Aspects of Nuclear Dynamics written by J.H. Koch and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 1988 Summer School on New Aspects of Nuclear Dynamics took place in the style that by now has become a tradition: a series of lectures by well known scientists on modem topics of nuclear physics, where special emphasis is placed on the didactic aspects of the lectures. In the past few years, we have witnessed a rapid evolution of the field of nuclear physics towards novel directions of research. This development is accompanied by the construction of some of the largest experimental facilities ever built for nuclear research. The subjects covered by the Summer School focussed on two main issues currently under active investigation and which will be pursued with the new facilities: the transition from nucleonic to quark degrees of freedom in the decription of nuclear reactions, and the behavior of nuclear matter as one approaches extreme densities and temperatures. These topics in many respects go beyond traditional nuclear physics and the speakers therefore also included high energy physicists. From the response of the participants it was clear that the program of the school filled a gap in the curriculum of many students. We wish to thank all the speakers for their well organized lectures, which were nicely geared to the level of the school, and for spending extra time on problem sessions and extensive discussions. The organization of this Summer School was made possible by substantial support from the Science Committee of the North Atlantic Treaty Organization.
Download or read book Baryon Transition Form Factors at JLab written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The measurements of exclusive single-meson and double-pion electro-production cross sections off the proton to study nucleon resonances will be extended to higher momentum transfers with the CLAS12 detector and the energy upgraded CEBAF beam. Based on new theoretical developments to extract and interpret the electromagnetic transition form factors and on the experience gained from the most recent results, the newly formed collaboration of experimentalists and theorists shall enable us to provide unprecedented high-precision data, high-quality analyses, and state-of-the-art model and QCD based calculations in a Q domain up to 10 GeV2. For the first time nucleon resonance structures will be studied at still unexplored distance scales, where the dressed quark contributions are the dominating degrees of freedom and their strong interaction is responsible for the ground and excited nucleon state formation. These studies also open up a promising opportunity to understand the origin of more than 98% of the nucleon mass that is created by strong fields predominantly at these distance scales by dressing the current quarks.
Download or read book Extraction of Electromagnetic Transition Form Factors for Nucleon Resonances Within a Dynamical Coupled Channels Model written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We explain the application of a recently developed analytic continuation method to extract the electromagnetic transition form factors for the nucleon resonances ($N^*$) within a dynamical coupled-channel model of meson-baryon reactions. Illustrative results of the obtained $N^*\rightarrow \gamma N$ transition form factors, defined at the resonance pole positions on the complex energy plane, for the well isolated $P_{33}$ and $D_{13}$, and the complicated $P_{11}$ resonances are presented. A formula has been developed to give an unified representation of the effects due to the first two $P_{11}$ poles, which are near the $\pi\Delta$ threshold, but are on different Riemann sheets. We also find that a simple formula, with its parameters determined in the Laurent expansions of $\pi N \rightarrow \pi N$ and $\gamma N \rightarrow\pi N$ amplitudes, can reproduce to a very large extent the exact solutions of the considered model at energies near the real parts of the extracted resonance positions. We indicate the differences between our results and those extracted from the approaches using the Breit-Wigner parametrization of resonant amplitudes to fit the data.
Download or read book Recent Results on the Nucleon Resonance Spectrum and Structure from the CLAS Detector written by and published by . This book was released on 2016 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\gamma_{v}pN^*$ transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and $N \rightarrow N^*$ transition form factors. We will also discuss further convincing evidences for a new baryon state $N^{\, '}(1720)3/2^+$ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
Download or read book Three dimensional Partonic Structure of the Nucleon written by Mauro Anselmino and published by IOS Press. This book was released on 2012 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: The three-dimensional nucleon structure is central to many theoretical and experimental activities, and research in this field has seen many advances in the last two decades, addressing fundamental questions such as the orbital motion of quarks and gluons inside the nucleons, their spatial distribution, and the correlation between spin and intrinsic motion. A real three-dimensional imaging of the nucleon as a composite object, both in momentum and coordinate space, is slowly emerging.This book presents lectures and seminars from the Enrico Fermi School Three-Dimensional Partonic Structure of the Nucleon, held in Varenna,
Download or read book Nstar 2001 Proceedings Of The Workshop On The Physics Of Excited Nucleons written by Dieter Drechsel and published by World Scientific. This book was released on 2001-08-28 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of N∗s can provide us with critical insights into the nature of QCD in the confinement domain. The keys to progress in this domain are the identification of its important degrees of freedom and the effective forces between them. The nucleon is the simplest system in which the nonabelian character of QCD is manifest. There are Nc quarks in a baryon because there are Nc colors, and as a consequence Gell-Mann and Zweig were forced to introduce the quarks in order to describe the octet and decuplet baryons.This volume gives a status report on the recent experimental and theoretical results in the field of nucleon resonance physics. A wealth of new high precision data was presented from facilities around the world, such as BES, BNL, ELSA, GRAAL, JLab, MAMI, MIT/Bates, SPring8, and Yerevan. Particular emphasis was laid on polarization degrees of freedom and large acceptance detectors as precision tools for studying small but important transition amplitudes, and the helicity (spin) structure of the nucleon. There were new results describing the nucleon resonance structure on the basis of quantum chromodynamics, either directly in terms of quarks and gluons by means of lattice gauge theory, or in terms of hadrons in the framework of chiral field theories. A status report on duality showed the surprising connections between the physics of the low energy nucleon resonance region and the realm of quark structure functions in deep inelastic scattering. Finally, this volume contains a summary report of the BRAG workshop, devoted to the analysis of baryon resonances.
Download or read book Excited Nucleons And Hadron Structure Proceedings Of The Nstar 2000 Conference written by Volker Burkert and published by World Scientific. This book was released on 2001-02-28 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: The conference NSTAR 2000 was part of a series of conferences and workshops that began in New York in 1988. Since then, the field of excited nucleons and hadron structure has developed enormously, and the scope has broadened. Most significantly, new experimental facilities have come into operation, allowing precise measurements of resonance couplings and transition form factors. The search for “missing” quark model states and gluonic excitations in complex hadronic channels is now possible.On the theory side, new and promising developments have emerged: quark models with meson degrees of freedom, hybrid baryon models, and studies of baryons in the limit of many colors. For the first time, lattice QCD has been employed to calculate masses of excited nucleons. Nucleon resonances are now recognized as providing significant contributions to the nucleon spin sum rules, as well as the Gerasimov-Drell-Hearn and Bjorken integrals, at finite momentum transfer.
Download or read book Excited Nucleons and Hadronic Structure written by V. Burkert and published by World Scientific. This book was released on 2001 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: The conference NSTAR 2000 was part of a series of conferences and workshops that began in New York in 1988. Since then, the field of excited nucleons and hadron structure has developed enormously, and the scope has broadened. Most significantly, new experimental facilities have come into operation, allowing precise measurements of resonance couplings and transition form factors. The search for ?missing? quark model states and gluonic excitations in complex hadronic channels is now possible.On the theory side, new and promising developments have emerged: quark models with meson degrees of freedom, hybrid baryon models, and studies of baryons in the limit of many colors. For the first time, lattice QCD has been employed to calculate masses of excited nucleons. Nucleon resonances are now recognized as providing significant contributions to the nucleon spin sum rules, as well as the Gerasimov-Drell-Hearn and Bjorken integrals, at finite momentum transfer.
Download or read book The Nucleon Resonance Program at Jlab written by Ralf W. Gothe and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The status of the program to study baryon resonances at Jefferson Lab will be exemplified by the latest results on resonance parameters and transition form factors in single and double-pion production as well as kaon-hyperon decays.
Download or read book Nucleon Form Factors from High Statistics Mixed action Calculations with 2 1 Flavors written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present new high-statistics results for nucleon form factors at pion masses of approximately 290, 350, 500, and 600 MeV using a mixed action of domain wall valence quarks on an improved staggered sea. We perform chiral fits to both vector and axial form factors and compare our results to experiment.
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 Theoretical Nuclear Physics in Italy written by G. Pisent and published by World Scientific. This book was released on 2001 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cortona Conference is a biennial meeting of all Italian groups from about 20 universities who are active in theoretical nuclear physics.This volume presents the main achievements and perspectives of Italian theoretical nuclear physics, with particular reference to the last two years.The first part contains the invited talks on: (1) Nuclear structure, (2) Light nuclei physics, (3) Hadronic degrees of freedom, (4) Nuclear physics with electroweak probes, (5) Nuclear dynamics and nuclear matter, and (6) First results about the AIACE experiment. Furthermore it includes two longer communications on: (7) Nuclear physics with exotic beams, and (8) Solution of the folding problem in protein models. The second part contains contributed papers.
Download or read book Nucleon Resonances And Nucleon Structure Proceedings Of The Institute For Nuclear Theory First Summer School written by Miller Gerald A and published by World Scientific. This book was released on 1992-08-07 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent experimental investigations of deep inelastic scattering, baryon form factors and high momentum transfer nuclear reactions have revealed many unexpected phenomena that suggest deep relationships between nucleon structure, hadronic spectroscopy and quantum chromodynamics. The proceedings of this summer school will help young researchers understand these topics and appreciate the importance of existing and expected data.This volume is the first of a series on the summer schools and workshops at the Institute for Nuclear Theory, which was opened at the University of Washington following the recommendation of the Nuclear Science Advisory Committee. The formation of this national institute was a response by the nuclear physics comunity to the shortage of nuclear theorists vis-a-vis experimentalists.
