Kaon electromagnetic form factors in dispersion theory
Abstract The electromagnetic form factors of charged and neutral kaons are strongly constrained by their low-energy singularities, in the isovector part from two-pion intermediate states and in the isoscalar contribution in terms of $$\omega $$ ω and $$\phi $$ ϕ residues. The former can be predicted...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2022-05-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | https://doi.org/10.1140/epjc/s10052-022-10348-3 |
| _version_ | 1828202664257650688 |
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| author | D. Stamen D. Hariharan M. Hoferichter B. Kubis P. Stoffer |
| author_facet | D. Stamen D. Hariharan M. Hoferichter B. Kubis P. Stoffer |
| author_sort | D. Stamen |
| collection | DOAJ |
| description | Abstract The electromagnetic form factors of charged and neutral kaons are strongly constrained by their low-energy singularities, in the isovector part from two-pion intermediate states and in the isoscalar contribution in terms of $$\omega $$ ω and $$\phi $$ ϕ residues. The former can be predicted using the respective $$\pi \pi \rightarrow {{\bar{K}}} K$$ π π → K ¯ K partial-wave amplitude and the pion electromagnetic form factor, while the latter parameters need to be determined from electromagnetic reactions involving kaons. We present a global analysis of time- and spacelike data that implements all of these constraints. The results enable manifold applications: kaon charge radii, elastic contributions to the kaon electromagnetic self energies and corrections to Dashen’s theorem, kaon boxes in hadronic light-by-light (HLbL) scattering, and the $$\phi $$ ϕ region in hadronic vacuum polarization (HVP). Our main results are: $$\langle r^2\rangle _\text {c}=0.359(3)\,\text {fm}^2$$ ⟨ r 2 ⟩ c = 0.359 ( 3 ) fm 2 , $$\langle r^2\rangle _\text {n}=-0.060(4)\,\text {fm}^2$$ ⟨ r 2 ⟩ n = - 0.060 ( 4 ) fm 2 for the charged and neutral radii, $$\epsilon =0.63(40)$$ ϵ = 0.63 ( 40 ) for the elastic contribution to the violation of Dashen’s theorem, $$a_\mu ^{K\text {-box}}=-0.48(1)\times 10^{-11}$$ a μ K -box = - 0.48 ( 1 ) × 10 - 11 for the charged kaon box in HLbL scattering, and $$a_\mu ^\text {HVP}[K^+K^-, \le 1.05\,\text {GeV}]=184.5(2.0)\times 10^{-11}$$ a μ HVP [ K + K - , ≤ 1.05 GeV ] = 184.5 ( 2.0 ) × 10 - 11 , $$a_\mu ^\text {HVP}[K_SK_L, \le 1.05\,\text {GeV}]=118.3(1.5)\times 10^{-11}$$ a μ HVP [ K S K L , ≤ 1.05 GeV ] = 118.3 ( 1.5 ) × 10 - 11 for the HVP integrals around the $$\phi $$ ϕ resonance. The global fit to $${{\bar{K}}} K$$ K ¯ K gives $${{\bar{M}}}_\phi =1019.479(5)\,\text {MeV}$$ M ¯ ϕ = 1019.479 ( 5 ) MeV , $${\bar{ \varGamma }}_\phi =4.207(8)\,\text {MeV}$$ Γ ¯ ϕ = 4.207 ( 8 ) MeV for the $$\phi $$ ϕ resonance parameters including vacuum-polarization effects. |
| first_indexed | 2024-04-12T11:52:24Z |
| format | Article |
| id | doaj.art-3da9d31044f547cda39c15c8e6033225 |
| institution | Directory Open Access Journal |
| issn | 1434-6052 |
| language | English |
| last_indexed | 2024-04-12T11:52:24Z |
| publishDate | 2022-05-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | European Physical Journal C: Particles and Fields |
| spelling | doaj.art-3da9d31044f547cda39c15c8e60332252022-12-22T03:34:08ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522022-05-0182511810.1140/epjc/s10052-022-10348-3Kaon electromagnetic form factors in dispersion theoryD. Stamen0D. Hariharan1M. Hoferichter2B. Kubis3P. Stoffer4Helmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universität BonnHelmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universität BonnAlbert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of BernHelmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universität BonnPhysik-Institut, Universität ZürichAbstract The electromagnetic form factors of charged and neutral kaons are strongly constrained by their low-energy singularities, in the isovector part from two-pion intermediate states and in the isoscalar contribution in terms of $$\omega $$ ω and $$\phi $$ ϕ residues. The former can be predicted using the respective $$\pi \pi \rightarrow {{\bar{K}}} K$$ π π → K ¯ K partial-wave amplitude and the pion electromagnetic form factor, while the latter parameters need to be determined from electromagnetic reactions involving kaons. We present a global analysis of time- and spacelike data that implements all of these constraints. The results enable manifold applications: kaon charge radii, elastic contributions to the kaon electromagnetic self energies and corrections to Dashen’s theorem, kaon boxes in hadronic light-by-light (HLbL) scattering, and the $$\phi $$ ϕ region in hadronic vacuum polarization (HVP). Our main results are: $$\langle r^2\rangle _\text {c}=0.359(3)\,\text {fm}^2$$ ⟨ r 2 ⟩ c = 0.359 ( 3 ) fm 2 , $$\langle r^2\rangle _\text {n}=-0.060(4)\,\text {fm}^2$$ ⟨ r 2 ⟩ n = - 0.060 ( 4 ) fm 2 for the charged and neutral radii, $$\epsilon =0.63(40)$$ ϵ = 0.63 ( 40 ) for the elastic contribution to the violation of Dashen’s theorem, $$a_\mu ^{K\text {-box}}=-0.48(1)\times 10^{-11}$$ a μ K -box = - 0.48 ( 1 ) × 10 - 11 for the charged kaon box in HLbL scattering, and $$a_\mu ^\text {HVP}[K^+K^-, \le 1.05\,\text {GeV}]=184.5(2.0)\times 10^{-11}$$ a μ HVP [ K + K - , ≤ 1.05 GeV ] = 184.5 ( 2.0 ) × 10 - 11 , $$a_\mu ^\text {HVP}[K_SK_L, \le 1.05\,\text {GeV}]=118.3(1.5)\times 10^{-11}$$ a μ HVP [ K S K L , ≤ 1.05 GeV ] = 118.3 ( 1.5 ) × 10 - 11 for the HVP integrals around the $$\phi $$ ϕ resonance. The global fit to $${{\bar{K}}} K$$ K ¯ K gives $${{\bar{M}}}_\phi =1019.479(5)\,\text {MeV}$$ M ¯ ϕ = 1019.479 ( 5 ) MeV , $${\bar{ \varGamma }}_\phi =4.207(8)\,\text {MeV}$$ Γ ¯ ϕ = 4.207 ( 8 ) MeV for the $$\phi $$ ϕ resonance parameters including vacuum-polarization effects.https://doi.org/10.1140/epjc/s10052-022-10348-3 |
| spellingShingle | D. Stamen D. Hariharan M. Hoferichter B. Kubis P. Stoffer Kaon electromagnetic form factors in dispersion theory European Physical Journal C: Particles and Fields |
| title | Kaon electromagnetic form factors in dispersion theory |
| title_full | Kaon electromagnetic form factors in dispersion theory |
| title_fullStr | Kaon electromagnetic form factors in dispersion theory |
| title_full_unstemmed | Kaon electromagnetic form factors in dispersion theory |
| title_short | Kaon electromagnetic form factors in dispersion theory |
| title_sort | kaon electromagnetic form factors in dispersion theory |
| url | https://doi.org/10.1140/epjc/s10052-022-10348-3 |
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