Download or read book Charged Pion Photoproduction And Scaling written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The gamma-n -->pi- p and gamma-p --> pi+ n reactions are essential probes of the transition from meson-nucleon degrees of freedom to quark-gluon degrees of freedom in exclusive processes. The cross sections of these processes are also advantageous, for the investigation of oscillatory behavior around the quark counting rule prediction, since they decrease relatively slower with energy compared with other photon-induced processes. In this talk, we discuss recent results on the gamma-p --> pi+ n and gamma-n -->pi- p processes from Jefferson Lab experiment E94-104. We also discuss the CLAS g10 analysis on the gamma-n -->pi- p process.

Download or read book Charged Pion Photoproduction written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We extracted the differential cross section for the gn --> pi-p process from a deuterium target using the CLAS detector at Jefferson Lab in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles (theta c.m.) between 50 deg. and 115 deg. We confirm a previous indication of a broad enhancement around a c.m. energy (sqrt s) of 2.1 GeV at theta c.m. =90 deg. in the scaled differential cross section, s^7 ds/dt and a rapid fall-off in a center-of-mass energy region of about 400 MeV following the enhancement. Our data show an angular dependence of this enhancement as the suggested scaling region is approached for theta c.m. from 70 deg. to 10 deg.

Download or read book Cross Section Measurement of Charged Pion Photoproduction from Hydrogen and Deuterium written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the differential cross section for the gamma n --> pi- p and gamma p --> pi+ n reactions at center of mass angle of 90 degree in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at photon energies greater than 3.3 GeV exhibit a global scaling behavior for both pi- and pi+ photoproduction, consistent with the constituent counting rule and the existing pi+ photoproduction data. Possible oscillations around the scaling value were observed. The cross section ratio of exclusive pi- to pi+ photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams. The data also indicate a resonance structure at a center-of-mass energy near 2.2 GeV.

Download or read book Charged Pion Photoproduction from Hydrogen and Deuterium at Jefferson Lab written by Haiyan Gao and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The {gamma}n {yields} {pi}{sup -}p and {gamma}p {yields} {pi}{sup +}n reactions are essential probes of the transition from meson-nucleon degrees of freedom to quark-gluon degrees of freedom in exclusive processes. The cross sections of these processes are also, advantageous, for the investigation of oscillatory behavior around the quark counting prediction, since they decrease relatively slower with energy compared with other photon-induced processes. Moreover, these photoreactions in nuclei can probe the QCD nuclear filtering and color transparency effects. In this talk, I discuss the preliminary results on the {gamma}p {yields} {pi}{sup +}n and {gamma}n {yields} {pi}{sup -}p processes at a center-of-mass angle of 90{sup o} from Jefferson Lab experiment E94-104. I also discuss a new experiment in which singles {gamma}p {yields} {pi}{sup +}n measurement from hydrogen, and coincidence {gamma}n {yields} {pi}{sup -}p measurements at the quasifree kinematics from deuterium and {sup 12}C for photon energies between 2.25 GeV to 5.8 GeV in fine steps at a center-of-mass angle of 90{sup o} are planned. The proposed measurement will allow a detailed investigation of the oscillatory scaling behavior in photopion production processes and the study of the nuclear dependence of rather mysterious oscillations with energy that previous experiments have indicated. The various nuclear and perturbative QCD approaches, ranging from Glauber theory, to quark-counting, to Sudakov-corrected independent scattering, make dramatically different predictions for the experimental outcomes.

Download or read book Charged Pion Photoproduction from Hydrogen and Deuterium at Jefferson Lab written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The [gamma]n [yields] [pi][sup -]p and [gamma]p [yields] [pi][sup +]n reactions are essential probes of the transition from meson-nucleon degrees of freedom to quark-gluon degrees of freedom in exclusive processes. The cross sections of these processes are also, advantageous, for the investigation of oscillatory behavior around the quark counting prediction, since they decrease relatively slower with energy compared with other photon-induced processes. Moreover, these photoreactions in nuclei can probe the QCD nuclear filtering and color transparency effects. In this talk, I discuss the preliminary results on the [gamma]p [yields] [pi][sup +]n and [gamma]n [yields] [pi][sup -]p processes at a center-of-mass angle of 90[sup o] from Jefferson Lab experiment E94-104. I also discuss a new experiment in which singles [gamma]p [yields] [pi][sup +]n measurement from hydrogen, and coincidence [gamma]n [yields] [pi][sup -]p measurements at the quasifree kinematics from deuterium and [sup 12]C for photon energies between 2.25 GeV to 5.8 GeV in fine steps at a center-of-mass angle of 90[sup o] are planned. The proposed measurement will allow a detailed investigation of the oscillatory scaling behavior in photopion production processes and the study of the nuclear dependence of rather mysterious oscillations with energy that previous experiments have indicated. The various nuclear and perturbative QCD approaches, ranging from Glauber theory, to quark-counting, to Sudakov-corrected independent scattering, make dramatically different predictions for the experimental outcomes.

Download or read book Exclusive Photoproduction of Charged Pions in Hydrogen and Deuterium from 1 to 6 GeV written by and published by . This book was released on 2004 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of the transition region in the description of exclusive processes and hadron structure, from the nucleon-meson degrees of freedom in meson-exchange models at low energy to the quark-gluon degrees of freedom in pQCD at high energy, is essential for us to understand the strong interaction. The differential cross section measurements for exclusive reactions at fixed center-of-mass angles enable us to investigate the constituent counting rule, which explicitly connects the quark-gluon degrees of freedom to the energy dependence of differential cross sections. JLab Experiment E94-104 was carried out in Hall A with two high resolution spectrometers. It included the coincidence cross section measurement for the ?n --> ?-[p] process with a deuterium target and the singles measurement for the ?p --> ?+[n] process with a hydrogen target. The untagged real photons were generated by the electron beam impinging on a copper radiator. The photon energies ranged from 1.1 to 5.5 GeV, corresponding to the center-of-mass energies from 1.7 to 3.4 GeV. The pion center-of-mass angles were fixed at 50 deg, 70 deg, 90 deg, and also 100 deg, 110 deg at a few energies. The JLab E94-104 data presented in this thesis contain four interesting features. The data exhibit a global scaling behavior for both ?- and ?+ photoproduction at high energies and high transverse momenta, consistent with the constituent counting rule and the existing ?+ photoproduction data. This implies that the quark-gluon degrees of freedom start to play a role at this energy scale. The data suggests possible substructure of the scaling behavior, which might be oscillations around the scaling value. There are several possible mechanisms that can cause oscillations, for example the one associated with the generalized constituent counting rule involving quark orbital angular momentum. The data show an enhancement in the scaled cross section at center-of-mass energy near 2.2 GeV, where baryon resonances are not as well known as those at low energies. The differential cross section ratios for exclusive ?n --> ?-[p] to ?p --> ?+[n] process at ?cm = 90 deg start to show consistency with the prediction based on one-hard-gluon-exchange diagrams at high energies.

Download or read book Charged Pion Photoproduction from 10B written by John Alexander Nelson and published by . This book was released on 1990 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Charged Pion Photoproduction from Light Nuclei written by Manohar Kularatnam Singham and published by . This book was released on 1980 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inclusive charged pion photoproduction on 1hn1 1hn2C C using tagged photons in the energy range 200 390 MeV written by and published by . This book was released on 1981 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book CHARGED PION PHOTOPRODUCTION RATIOS AND THE QUARK MODEL written by I. Barbour and published by . This book was released on with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Near threshold Charged Pion Photoproduction from sup 13 C written by John J. LeRose and published by . This book was released on 1981 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inclusive Charged Pion Photoproduction on 12 C Using Tagged Photons in the Energy Range 200 390 MeV written by Jürgen Arends and published by . This book was released on 1981 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Near threshold Charged Pion Photoproduction from sup10 B and sup11 B written by Dana P. Rowley and published by . This book was released on 1981 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1979 with total page 1180 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976-05 with total page 912 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quark hadron Duality And The Transition To Pqcd Proceedings Of The First Workshop written by Simonetta Liuti and published by World Scientific. This book was released on 2006-02-06 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: While perturbative QCD methods fully describe experimental results at high energies, and chiral perturbation theory is the low energy effective theory of the strong interactions, a form of duality is observed connecting these two regimes. In these intermediate kinematics, a wide variety of reactions are observed which can be described simultaneously by single particle (quark) scattering, and by exclusive resonance (hadron) scattering.The contributions in this proceedings volume discuss recent and existing results, and aim to foster current and future research, investigating the phenomenon of quark-hadron duality.This unique volume contains research work by scientists from different arenas of hadronic physics, dealing with different manifestations of quark-hadron duality.

Download or read book 10th Conference on the Intersections of Particle and Nuclear Physics written by Marvin L. Marshak and published by American Institute of Physics. This book was released on 2010-01-11 with total page 1010 pages. Available in PDF, EPUB and Kindle. Book excerpt: CIPANP 2009 explores areas of common interest between nuclear physicists, high energy (particle) physicists and astrophysicists. These areas range from studies of the strong interactions that bind nuclei together to physics of the very early Universe and include such topics as neutrinos, hadron physics, spin physics, heavy ion physics, QCD and heavy flavor physics. The Conference papers include descriptions of searches for "new physics", phenomena that cannot be accounted for by current theories.