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Title: Proton-proton bremsstrahlung: Consequences of different on-shell-point conditions

Abstract

Background: Proton-proton bremsstrahlung (pp{gamma}) is investigated both theoretically and experimentally. The pp{gamma} amplitudes can be classified according to the number and location of on-shell points at which they are evaluated. Quantitative understanding of the effect on the pp{gamma} cross section of using different on-shell-point conditions is lacking, but it is essential to identifying the photon emission mechanism governing the pp{gamma} process. Method: Four different pp{gamma} amplitudes, which include four-on-shell-point amplitudes and one-on-shell-point amplitude, are generated from a realistic one-boson-exchange (ROBE) model for pp scattering. These ROBE amplitudes are used to investigate the consequence of using different on-shell-point conditions in calculating the pp{gamma} cross sections. Purpose: We verify the validity of the ROBE pp{gamma} amplitudes. We explore similarities between the four-on-shell-point ROBE and two-u-two-t special (TuTts) soft-photon pp{gamma} amplitudes and important differences with the one-on-shell-point ROBE and Low pp{gamma} amplitudes. We demonstrate that the precision Kernfysisch Versneller Instituut (KVI) data can only be described by the four-on-shell-point (ROBE or TuTts) amplitude. We use the ROBE four-on-shell-point amplitude and one-on-shell-point amplitude to investigate systematically the effect of using different on-shell-point conditions to calculate the pp{gamma} cross section. Furthermore, we identify a general principle that governs the process. This general principle is alsomore » applicable to other bremsstrahlung processes involving the scattering of two identical nucleons. Results: (i) The four-on-shell-point ROBE (or TuTts) amplitude describes the high-precision KVI data much better than does the one-on-shell-point ROBE (or Low) amplitude. Although the contribution from the anomalous magnetic moment of the proton is very significant, it does not completely dominate the KVI pp{gamma} cross sections. (ii) The four-on-shell-point ROBE (or TuTts) amplitude describes the TRIUMF data better than does the one-on-shell-point ROBE (or Low) amplitude. (iii) The effect on the pp{gamma} cross section of using different on-shell-point conditions is significant in the hard-photon region, i.e., for small proton scattering angles {theta} (={theta}{sub 3}={theta}{sub 4}, symmetric scattering angles) far from the elastic limit ({theta}{yields}45 deg.); in contrast, the effect becomes insignificant in the vicinity of the elastic limit. Near the limit as {theta} tends to 45 deg. (or as the photon energy K approaches zero), the four-on-shell-point and one-on-shell-point amplitudes approach one another, a general principle applicable to all bremsstrahlung processes because only kinematics is involved. Conclusion: The four-on-shell-point ROBE amplitude provides a quantitative description of pp{gamma} cross sections. The anomalous magnetic moment is an important component of the photon emission mechanism. The four-on-shell-point property of the full ROBE amplitude is essential to properly describing the complete range of the precision KVI data and the TRIUMF data, although the one-on-shell-point ROBE amplitude is adequate in the region near the elastic limit.« less

Authors:
; ; ;  [1];  [2];  [2];  [2]
  1. College of Physics and Technology, Guangxi University, Nanning, Guangxi 530004 (China)
  2. (United States)
Publication Date:
OSTI Identifier:
21596731
Resource Type:
Journal Article
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 84; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevC.84.034007; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2813
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ACCURACY; AMPLITUDES; BOSON-EXCHANGE MODELS; BREMSSTRAHLUNG; CROSS SECTIONS; KVI; MAGNETIC MOMENTS; PHOTON EMISSION; PHOTONS; PROTON-PROTON INTERACTIONS; PROTONS; SCATTERING; SYMMETRY; BARYON-BARYON INTERACTIONS; BARYONS; BOSONS; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; EMISSION; FERMIONS; HADRON-HADRON INTERACTIONS; HADRONS; INTERACTIONS; MASSLESS PARTICLES; MATHEMATICAL MODELS; NATIONAL ORGANIZATIONS; NETHERLANDS ORGANIZATIONS; NUCLEON-NUCLEON INTERACTIONS; NUCLEONS; PARTICLE INTERACTIONS; PARTICLE MODELS; PERIPHERAL MODELS; PROTON-NUCLEON INTERACTIONS; RADIATIONS

Citation Formats

Li, Yi, Liou, M. K., Schreiber, W. M., Gibson, B. F., Department of Physics and Institute for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210, Department of Physics, College of Staten Island of the City University of New York, Staten Island, New York 10314, and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Proton-proton bremsstrahlung: Consequences of different on-shell-point conditions. United States: N. p., 2011. Web. doi:10.1103/PHYSREVC.84.034007.
Li, Yi, Liou, M. K., Schreiber, W. M., Gibson, B. F., Department of Physics and Institute for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210, Department of Physics, College of Staten Island of the City University of New York, Staten Island, New York 10314, & Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Proton-proton bremsstrahlung: Consequences of different on-shell-point conditions. United States. doi:10.1103/PHYSREVC.84.034007.
Li, Yi, Liou, M. K., Schreiber, W. M., Gibson, B. F., Department of Physics and Institute for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210, Department of Physics, College of Staten Island of the City University of New York, Staten Island, New York 10314, and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Thu . "Proton-proton bremsstrahlung: Consequences of different on-shell-point conditions". United States. doi:10.1103/PHYSREVC.84.034007.
@article{osti_21596731,
title = {Proton-proton bremsstrahlung: Consequences of different on-shell-point conditions},
author = {Li, Yi and Liou, M. K. and Schreiber, W. M. and Gibson, B. F. and Department of Physics and Institute for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210 and Department of Physics, College of Staten Island of the City University of New York, Staten Island, New York 10314 and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545},
abstractNote = {Background: Proton-proton bremsstrahlung (pp{gamma}) is investigated both theoretically and experimentally. The pp{gamma} amplitudes can be classified according to the number and location of on-shell points at which they are evaluated. Quantitative understanding of the effect on the pp{gamma} cross section of using different on-shell-point conditions is lacking, but it is essential to identifying the photon emission mechanism governing the pp{gamma} process. Method: Four different pp{gamma} amplitudes, which include four-on-shell-point amplitudes and one-on-shell-point amplitude, are generated from a realistic one-boson-exchange (ROBE) model for pp scattering. These ROBE amplitudes are used to investigate the consequence of using different on-shell-point conditions in calculating the pp{gamma} cross sections. Purpose: We verify the validity of the ROBE pp{gamma} amplitudes. We explore similarities between the four-on-shell-point ROBE and two-u-two-t special (TuTts) soft-photon pp{gamma} amplitudes and important differences with the one-on-shell-point ROBE and Low pp{gamma} amplitudes. We demonstrate that the precision Kernfysisch Versneller Instituut (KVI) data can only be described by the four-on-shell-point (ROBE or TuTts) amplitude. We use the ROBE four-on-shell-point amplitude and one-on-shell-point amplitude to investigate systematically the effect of using different on-shell-point conditions to calculate the pp{gamma} cross section. Furthermore, we identify a general principle that governs the process. This general principle is also applicable to other bremsstrahlung processes involving the scattering of two identical nucleons. Results: (i) The four-on-shell-point ROBE (or TuTts) amplitude describes the high-precision KVI data much better than does the one-on-shell-point ROBE (or Low) amplitude. Although the contribution from the anomalous magnetic moment of the proton is very significant, it does not completely dominate the KVI pp{gamma} cross sections. (ii) The four-on-shell-point ROBE (or TuTts) amplitude describes the TRIUMF data better than does the one-on-shell-point ROBE (or Low) amplitude. (iii) The effect on the pp{gamma} cross section of using different on-shell-point conditions is significant in the hard-photon region, i.e., for small proton scattering angles {theta} (={theta}{sub 3}={theta}{sub 4}, symmetric scattering angles) far from the elastic limit ({theta}{yields}45 deg.); in contrast, the effect becomes insignificant in the vicinity of the elastic limit. Near the limit as {theta} tends to 45 deg. (or as the photon energy K approaches zero), the four-on-shell-point and one-on-shell-point amplitudes approach one another, a general principle applicable to all bremsstrahlung processes because only kinematics is involved. Conclusion: The four-on-shell-point ROBE amplitude provides a quantitative description of pp{gamma} cross sections. The anomalous magnetic moment is an important component of the photon emission mechanism. The four-on-shell-point property of the full ROBE amplitude is essential to properly describing the complete range of the precision KVI data and the TRIUMF data, although the one-on-shell-point ROBE amplitude is adequate in the region near the elastic limit.},
doi = {10.1103/PHYSREVC.84.034007},
journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 3,
volume = 84,
place = {United States},
year = {2011},
month = {9}
}