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Title: Flavor dependence of the pion and kaon form factors and parton distribution functions

Abstract

The separate quark flavor contributions to the pion and kaon valence quark distribution functions are studied, along with the corresponding electromagnetic form factors in the space-like region. The calculations are made using the solution of the Bethe-Salpeter equation for the model of Nambu and Jona-Lasinio with proper-time regularization. Both the pion and kaon form factors and the valence quark distribution functions reproduce many features of the available empirical data. The larger mass of the strange quark naturally explains the empirical fact that the ratio u(K) + (x)/u(pi) + (x) drops below unity at large x, with a value of approximately M$$2\atop{u}$$/Ms$$2\atop{s}$$ as x → 1. With regard to the elastic form factors we report a large flavor dependence, with the u-quark contribution to the kaon form factor being an order of magnitude smaller than that of the s-quark at large Q 2, which may be a sensitive measure of confinement effects in QCD. Surprisingly though, the total K + and π + form factors differ by only 10%. Lastly, in general we find that flavor breaking effects are typically around 20%.

Authors:
 [1];  [2];  [1]
  1. Univ. of Adelaide, SA (Australia). CSSM and ARC Centre of Excellence for Particle Physics at the Terascale, Dept. of Physics
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Physics Division
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); Australian Research Council (ARC)
OSTI Identifier:
1374563
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 94; Journal Issue: 3; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; elastic form factors; NJL model; parton distribution functions

Citation Formats

Hutauruk, Parada T. P., Cloët, Ian C., and Thomas, Anthony W. Flavor dependence of the pion and kaon form factors and parton distribution functions. United States: N. p., 2016. Web. doi:10.1103/PhysRevC.94.035201.
Hutauruk, Parada T. P., Cloët, Ian C., & Thomas, Anthony W. Flavor dependence of the pion and kaon form factors and parton distribution functions. United States. doi:10.1103/PhysRevC.94.035201.
Hutauruk, Parada T. P., Cloët, Ian C., and Thomas, Anthony W. 2016. "Flavor dependence of the pion and kaon form factors and parton distribution functions". United States. doi:10.1103/PhysRevC.94.035201. https://www.osti.gov/servlets/purl/1374563.
@article{osti_1374563,
title = {Flavor dependence of the pion and kaon form factors and parton distribution functions},
author = {Hutauruk, Parada T. P. and Cloët, Ian C. and Thomas, Anthony W.},
abstractNote = {The separate quark flavor contributions to the pion and kaon valence quark distribution functions are studied, along with the corresponding electromagnetic form factors in the space-like region. The calculations are made using the solution of the Bethe-Salpeter equation for the model of Nambu and Jona-Lasinio with proper-time regularization. Both the pion and kaon form factors and the valence quark distribution functions reproduce many features of the available empirical data. The larger mass of the strange quark naturally explains the empirical fact that the ratio u(K) + (x)/u(pi) + (x) drops below unity at large x, with a value of approximately M$2\atop{u}$/Ms$2\atop{s}$ as x → 1. With regard to the elastic form factors we report a large flavor dependence, with the u-quark contribution to the kaon form factor being an order of magnitude smaller than that of the s-quark at large Q2, which may be a sensitive measure of confinement effects in QCD. Surprisingly though, the total K+ and π+ form factors differ by only 10%. Lastly, in general we find that flavor breaking effects are typically around 20%.},
doi = {10.1103/PhysRevC.94.035201},
journal = {Physical Review C},
number = 3,
volume = 94,
place = {United States},
year = 2016,
month = 9
}

Journal Article:
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  • Cited by 1
  • A rainbow-ladder truncation of QCD's Dyson-Schwinger equations, constrained by existing applications to hadron physics, is employed to compute the valence-quark parton distribution functions of the pion and kaon. Comparison is made to {pi}-N Drell-Yan data for the pion's u-quark distribution and to Drell-Yan data for the ratio u{sub K}(x)/u{sub {pi}}(x): the environmental influence of this quantity is a parameter-free prediction, which agrees well with existing data. Our analysis unifies the computation of distribution functions with that of numerous other properties of pseudoscalar mesons.
  • A rainbow-ladder truncation of QCD's Dyson-Schwinger equations, constrained by existing applications to hadron physics, is employed to compute the valence-quark parton distribution functions of the pion and kaon. Comparison is made to {pi}-N Drell-Yan data for the pion's u-quark distribution and to Drell-Yan data for the ratio u{sub K}(x)/u{sub {pi}}(x): the environmental influence of this quantity is a parameter-free prediction, which agrees well with existing data. Our analysis unifies the computation of distribution functions with that of numerous other properties of pseudoscalar mesons.
  • Cited by 5
  • The structure of hadrons is described well by the Nambu-Jona-Lasinio (NJL) model, which is a chiral effective quark theory of QCD. In this work we explore the electromagnetic structure of the pion and kaon using the three-flavor NJL model in the proper-time regularization scheme, including effects of the pion cloud at the quark level. In the calculation there is only one free parameter, which we take as the dressed light quark (u and d) mass. In the regime where the dressed light quark mass is approximately 0.25 GeV we find that the calculated values of the kaon decay constant, currentmore » quark masses, and quark condensates are consistent with experiment- and QCD-based analyses. We also investigate the dressed light quark mass dependence of the pion and kaon electromagnetic form factors, where comparison with empirical data and QCD predictions also favors a dressed light quark mass near 0.25 GeV.« less