Author: Cornelis Pieter LouwersePublisher:
ISBN:
Category :
Languages : en
Pages : 145
Book Description
Dispersion Relation Calculations for Pion Electroproduction and Compton Scattering
Author: Cornelis Pieter LouwersePublisher:
ISBN:
Category :
Languages : en
Pages : 145
Book Description
Dispersion relation calculations for pion electroproduction and...
Author: Cornelis Pieter LouwersePublisher:
ISBN:
Category :
Languages : en
Pages : 158
Book Description
Dispersion Relation Calculations for Pion Elektroproduction and Compton Scattering
Author: Cornelis Pieter LouwersePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Low Momentum Transfer Measurements of Pion Electroproduction and Virtual Compton Scattering at the Delta Resonance
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 123
Book Description
Non-spherical components of the nucleon wave function are measured through p(e, e'p)[pi]0 experiment at the [Delta]+(1232) resonance for Q2 = 0.04, 0.09, and 0.13 (GeV=c)2 utilizing the Jefferson National Accelerator Facility (JLab) pulsed beam and Hall A spectrometers. The new data extend the measurements of the Coulomb quadrupole amplitude to the lowest momentum transfer ever reached. The results disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The reported measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements. The Coulomb to magnetic multipole ratio (CMR) and generalized polarizability (GP) of the nucleon are also measured through virtual Compton scattering (VCS) for Q2 = 0.2(GeV=c)2 utilizing the Mainz Microtron (MAMI) continuous beam and A1 spectrometers. This data represents the first low Q2 GP measurement at the [Delta]+(1232) resonance. The GP measurement explores a region where previous data and theoretical calculations disagree. The CMR measurement will be the first VCS extraction to compare with world data generated through pion electroproduction. The Dispersion Relation (DR) model used for the VCS extraction provides a new theoretical framework for the data signal and backgrounds that is largely independent from the pion electroproduction models. The independence of the DR from the traditional models provides a strong crosscheck on the ability of the models to isolate the data signal.
Nuclear Science Abstracts
Author: Dispersion Approach to Real and Virtual Compton Scattering
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In recent years, new precision experiments have become possible withthe high luminosity accelerator facilities at MAMIand JLab, supplyingphysicists with precision data sets for different hadronic reactions inthe intermediate energy region, such as pion photo- andelectroproduction and real and virtual Compton scattering. By means of the low energy theorem (LET), the global properties of thenucleon (its mass, charge, and magnetic moment) can be separated fromthe effects of the internal structure of the nucleon, which areeffectively described by polarizabilities. Thepolarizabilities quantify the deformation of the charge andmagnetization densities inside the nucleon in an applied quasistaticelectromagnetic field. The present work is dedicated to develop atool for theextraction of the polarizabilities from these precise Compton data withminimum model dependence, making use of the detailed knowledge of pionphotoproduction by means of dispersion relations (DR). Due to thepresence of t-channel poles, the dispersion integrals for two ofthe six Compton amplitudes diverge. Therefore, we have suggested to subtract the s-channel dispersion integrals at zero photon energy($nu=0$). The subtraction functions at $nu=0$ are calculated through DRin the momentum transfer t at fixed $nu=0$, subtracted at t=0. For this calculation, we use the information about the t-channel process, $gammagammatopipito Nbar{N}$. In this way, four of thepolarizabilities can be predicted using the unsubtracted DR in the $s$-channel. The other two, $alpha-beta$ and $gamma_pi$, are free parameters in ourformalism and can be obtained from a fit to the Compton data. We present the results for unpolarized and polarized RCS observables, %in the kinematics of the most recent experiments, and indicate anenhanced sensitivity to the nucleon polarizabilities in theenergy range between pion production threshold and the $Delta(1232)$-resonance.newlineindentFurthermore, we extend the DR formalism to virtual Compton scatter.
Dispersion Relations for Compton Scattering
Author: Richard Edwin PrangePublisher:
ISBN:
Category : Dispersion
Languages : en
Pages : 13
Book Description
Many Body Structure of Strongly Interacting Systems
Author: Hartmuth ArenhövelPublisher: Springer Science & Business Media
ISBN: 3540367543
Category : Science
Languages : en
Pages : 218
Book Description
This carefully edited proceedings volume provides an extensive review and analysis of the work carried out over the past 20 years at the Mainz Microtron (MAMI). This research is centered on the application of Quantum Chromodynamics in the strictly nonperturbative regime at hadronic scales of about 1 fm. The book goes further to offer an outlook on the next wave research, with the forthcoming upgrade of MAMI.
Nuclear Science Abstracts
Author: A Study of the Partial Wave Dispersion Relations for Pion-nucleon Scattering
Author: Leonard Micajah SimmonsPublisher:
ISBN:
Category : Mesons
Languages : en
Pages : 154
Book Description