Long-distance contribution to {ital s}{r_arrow}{ital d}{gamma} and implications for {Omega}{sup {minus}}{r_arrow}{Xi}{sup {minus}}{gamma}, {ital B}{sub {ital s}}{r_arrow}{ital B}{sub {ital d}}{sup {asterisk}}{gamma}, and {ital b}{r_arrow}{ital s}{gamma}
- Department of Physics, Technion -- Israel Institute of Technology, Haifa 32000 (Israel)
We estimate the long-distance (LD) contribution to the magnetic part of the {ital s}{r_arrow}{ital d}{gamma} transition using the vector meson dominance approximation ({ital V}={rho},{omega},{psi}{sub {ital i}}). We find that this contribution may be significantly larger than the short-distance (SD) contribution to {ital s}{r_arrow}{ital d}{gamma} and could possibly saturate the present experimental upper bound on the {Omega}{sup {minus}}{r_arrow}{Xi}{sup {minus}}{gamma} decay rate, {Gamma}{sub {Omega}{sup {minus}}{r_arrow}{Xi}{sup {minus}}{gamma}}{sup max}{approx_equal}3.7{times}10{sup {minus}9} eV. For the decay {ital B}{sub {ital s}}{r_arrow}{ital B}{sub {ital d}}{sup {asterisk}}{gamma}, which is driven by {ital s}{r_arrow}{ital d}{gamma} as well, we obtain an upper bound on the branching ratio {ital B}({ital B}{sub {ital s}}{r_arrow}{ital B}{sub {ital d}}{sup {asterisk}}{gamma}){lt}3{times}10{sup {minus}8} from {Gamma}{sub {Omega}{sup {minus}}{r_arrow}{Xi}{sup {minus}}{gamma}}{sup max}. Barring the possibility that the quantum chromodynamics coefficient {ital a}{sub 2}({ital m}{sup 2}{sub {ital s}}) is much smaller than 1, {Gamma}{sub {Omega}{sup {minus}}{r_arrow}{Xi}{sup {minus}}{gamma}}{sup max} also implies the approximate relation 2/3{summation}{sub {ital ig}}{sub {psi}{sub {ital i}}}{sup 2}(0)/{ital m}{sub {psi}{sub {ital i}}}{sup 2}{approx_equal}1/2{ital g}{sub {rho}}{sup 2}(0) /{ital m}{sub {rho}}{sup 2}+1/6{ital g}{sub {omega}}{sup 2}(0)/{ital m}{sub {omega}}{sup 2}. This relation agrees quantitatively with a recent independent estimate of the left-hand side by Deshpande, He, and Trampetic, confirming that the LD contributions to {ital b}{r_arrow}{ital s}{gamma} are small. We find that these amount to an increase of (4{plus_minus}2){percent} in the magnitude of the {ital b}{r_arrow}{ital s}{gamma} transition amplitude, relative to the SD contribution alone. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 282850
- Journal Information:
- Physical Review, D, Journal Name: Physical Review, D Journal Issue: 7 Vol. 53; ISSN PRVDAQ; ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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