skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Exposing strangeness: Projections for kaon electromagnetic form factors

Abstract

A continuum approach to the kaon and pion bound-state problems is used to reveal their electromagnetic structure. For both systems, when used with parton distribution amplitudes appropriate to the scale of the experiment, Standard Model hard-scattering formulas are accurate to within 25% at momentum transfers Q 2 ≈ 8 GeV 2. There are measurable differences between the distribution of strange and normal matter within the kaons, e.g. the ratio of their separate contributions reaches a peak value of 1.5 at Q 2 ≈ 6 GeV 2. Its subsequent Q 2 evolution is accurately described by the hard scattering formulas. Projections for the ratio of kaon and pion form factors at timelike momenta beyond the resonance region are also presented. In conclusion, these results and projections should prove useful in planning next-generation experiments.

Authors:
 [1];  [2];  [1];  [3];  [4]
  1. Peking Univ., Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
  2. Nankai Univ., Tianjin (China)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Kent State Univ., Kent, OH (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Natural Science Foundation of China (NNSFC); National Key Basic Research Program of China; USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1389615
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 96; Journal Issue: 3; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS

Citation Formats

Gao, Fei, Chang, Lei, Liu, Yu -Xin, Roberts, Craig D., and Tandy, Peter C.. Exposing strangeness: Projections for kaon electromagnetic form factors. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.96.034024.
Gao, Fei, Chang, Lei, Liu, Yu -Xin, Roberts, Craig D., & Tandy, Peter C.. Exposing strangeness: Projections for kaon electromagnetic form factors. United States. doi:10.1103/PhysRevD.96.034024.
Gao, Fei, Chang, Lei, Liu, Yu -Xin, Roberts, Craig D., and Tandy, Peter C.. 2017. "Exposing strangeness: Projections for kaon electromagnetic form factors". United States. doi:10.1103/PhysRevD.96.034024.
@article{osti_1389615,
title = {Exposing strangeness: Projections for kaon electromagnetic form factors},
author = {Gao, Fei and Chang, Lei and Liu, Yu -Xin and Roberts, Craig D. and Tandy, Peter C.},
abstractNote = {A continuum approach to the kaon and pion bound-state problems is used to reveal their electromagnetic structure. For both systems, when used with parton distribution amplitudes appropriate to the scale of the experiment, Standard Model hard-scattering formulas are accurate to within 25% at momentum transfers Q2 ≈ 8 GeV2. There are measurable differences between the distribution of strange and normal matter within the kaons, e.g. the ratio of their separate contributions reaches a peak value of 1.5 at Q2 ≈ 6 GeV2. Its subsequent Q2 evolution is accurately described by the hard scattering formulas. Projections for the ratio of kaon and pion form factors at timelike momenta beyond the resonance region are also presented. In conclusion, these results and projections should prove useful in planning next-generation experiments.},
doi = {10.1103/PhysRevD.96.034024},
journal = {Physical Review D},
number = 3,
volume = 96,
place = {United States},
year = 2017,
month = 8
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on August 28, 2018
Publisher's Version of Record

Save / Share:
  • Using 20.7 pb{sup -1} of e{sup +}e{sup -} annihilation data taken at {radical}(s)=3.671 GeV with the CLEO-c detector, precision measurements of the electromagnetic form factors of the charged pion, charged kaon, and proton have been made for timelike momentum transfer of |Q{sup 2}|=13.48 GeV{sup 2} by the reaction e{sup +}e{sup -}{yields}h{sup +}h{sup -}. The measurements are the first ever with identified pions and kaons of vertical bar Q{sup 2} vertical bar>4 GeV{sup 2}, with the results F{sub {pi}}(13.48 GeV{sup 2})=0.075{+-}0.008(stat){+-}0.005(syst) and F{sub K}(13.48 GeV{sup 2})=0.063{+-}0.004(stat){+-}0.001(syst). The result for the proton, assuming G{sub E}{sup p}=G{sub M}{sup p}, is G{sub M}{sup p}(13.48more » GeV{sup 2})=0.014{+-}0.002(stat){+-}0.001(syst), which is in agreement with earlier results.« less
  • Using 20.7 pb-1 of e+e- annihilation data taken at {radical}(s) = 3.671 GeV with the CLEO-c detector, precision measurements of the electromagnetic form factors of the charged pion, charged kaon, and proton have been made for timelike momentum transfer of Q2= 13.48 GeV2 by the reaction e+e- {yields} h+h-. The measurements are the first ever with identified pions and kaons of 2 > 4 GeV2, with the results F{pi}(13.48 GeV2) = 0.075 {+-} 0.008(stat) {+-} 0.005(syst) and FK( 13.48 GeV2) =s 0.063 {+-} 0.004(stat) {+-} 0.001(syst). The result for the proton, assuming G{sub E}{sup p} = G{sub M}{sup p}, ismore » G{sub M}{sup p}(13.48 GeV{sup 2}) 0.014 {+-} 0.002(stat) {+-} 0.001(syst), which is in agreement with earlier results.« less
  • We investigate the pion and kaon ({pi}{sup +}, K{sup +}, K{sup 0}) electromagnetic form factors in the spacelike region: Q{sup 2} < or approx. 1 GeV, based on the gauged low-energy effective chiral action from the instanton vacuum in the large N{sub c} limit. Explicit flavor SU(3) symmetry breaking is taken into account. The nonlocal contributions turn out to be crucial to reproduce the experimental data. While the pion electromagnetic form factor is in good agreement with the data, the kaon one seems underestimated. We also calculate the electromagnetic charge radii for the pion and kaon: <r{sup 2}>{sub {pi}{sup +}}=0.455more » fm{sup 2}, <r{sup 2}>{sub K{sup +}}=0.534 fm{sup 2}, and <r{sup 2}>{sub K{sup 0}}=-0.060 fm{sup 2} without any adjustable free parameter except for the average instanton size and interinstanton distance, and they are compatible with the experimental data. The low-energy constant L{sub 9} in the large N{sub c} limit is estimated to be 8.42x10{sup -3} from the pion charge radius.« less
  • We analyze the electromagnetic pion and kaon form factor by including radiative and higher-twist effects within the framework of resummed perturbative QCD in the spacelike region. We focus on the transition from the perturbative to nonperturbative behavior in the phenomenological intermediate-energy regime. Using a modified ''k{sub T}'' factorization scheme with transverse degrees of freedom, we evaluate the nonperturbative soft contributions as distinct from the hard contributions, ensuring no double counting via the Ward identity at Q{sup 2}=0. The soft contributions are obtained via local quark-hadron duality, while the hard contributions rest on the well-known collinear factorization theorem using model wavemore » functions with modified Brodsky-Huang-Lepage-type ansatz and distribution amplitudes derived from light-cone QCD sum rules. Our analysis shows that the perturbative hard part prevails for large Q{sup 2} beyond 50-100 GeV{sup 2}, while for low and moderate momentum transfers below 10-16 GeV{sup 2}, the soft contributions dominate over the hard part. Thus, we demonstrate the importance of including the soft contributions for explaining the experimental form-factor data.« less