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A study of some rare eta-meson decays Peters, Daniel J.
Abstract
Previous calculations of the rate of the decay η → π⁰ γγ have fallen short of the experimental result, 0.84 ± 0.18 eV. One such calculation, that of vector meson dominance (VMD), is included herein (giving 0.29₋₀.₁₂⁺⁰¹⁶ eV), and moreover is modified by the inclusion of an added ingredient, the scalar meson α₀. The added mechanism does not adequately fix the result; assuming constructive interference the calculated rate becomes 0.37₋₀.₁₅⁺⁰²⁰ eV. The rate is then calculated according to a quark-box mechanism, where the ηqq and πqq couplings are fixed by the rates of the η→γγ and π⁰→ γγ decays. With constituent quark masses of 300 MeV for u and d quarks the calculated rate is 0.70±0.12 eV, which is in good agreement with experiment. Lower bounds (the unitarity limits) for the decays η → π⁰ e⁺e⁻ and η → π⁰ μ⁺ μ⁻ are calculated, using the intermediate state π⁰ γγ. The available experimental information is inadequate for purposes of a model-free calculation of these unitarity limits; therefore, the models considered for η → π⁰ γγ are used in these calculations. Using the quark box mechanism as above, the unitarity limits are 2.9 ± 0.5 μeV and 4.3 ± 0.7 μeV, for η → π⁰e⁺e⁻ and η → π⁰ μ⁺ μ⁻ respectively. These results show that the measurement of these (as yet unseen) modes at η factories such as that of Saturne can be expected.
Item Metadata
Title |
A study of some rare eta-meson decays
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1993
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Description |
Previous calculations of the rate of the decay η → π⁰ γγ have fallen short of the experimental result, 0.84 ± 0.18 eV. One such calculation, that of vector meson dominance
(VMD), is included herein (giving 0.29₋₀.₁₂⁺⁰¹⁶ eV), and moreover is modified by the inclusion of an added ingredient, the scalar meson α₀. The added mechanism does not
adequately fix the result; assuming constructive interference the calculated rate becomes
0.37₋₀.₁₅⁺⁰²⁰ eV. The rate is then calculated according to a quark-box mechanism, where the
ηqq and πqq couplings are fixed by the rates of the η→γγ and π⁰→ γγ decays. With
constituent quark masses of 300 MeV for u and d quarks the calculated rate is 0.70±0.12
eV, which is in good agreement with experiment.
Lower bounds (the unitarity limits) for the decays η → π⁰ e⁺e⁻ and η → π⁰ μ⁺ μ⁻ are
calculated, using the intermediate state π⁰ γγ. The available experimental information is
inadequate for purposes of a model-free calculation of these unitarity limits; therefore,
the models considered for η → π⁰ γγ are used in these calculations. Using the quark
box mechanism as above, the unitarity limits are 2.9 ± 0.5 μeV and 4.3 ± 0.7 μeV, for
η → π⁰e⁺e⁻ and η → π⁰ μ⁺ μ⁻ respectively. These results show that the measurement
of these (as yet unseen) modes at η factories such as that of Saturne can be expected.
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Extent |
1166084 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-04-10
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0085654
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.