ar X iv : 0 70 8 . 16 59 v 1 [ he p - ph ] 1 3 A ug 2 00 7 Improved dispersion relations for γγ → π 0 π 0
نویسندگان
چکیده
We perform a dispersive theoretical study of the reaction γγ → ππ emphasizing the low energy region. The large source of theoretical uncertainty to calculate the γγ → ππ total cross section for √ s & 0.5 GeV within the dispersive approach is removed. This is accomplished by taking one more subtraction in the dispersion relations, where the extra subtraction constant is fixed by considering new low energy constraints, one of them further refined by taking into consideration the f0(980) region. This allows us to make sharper predictions for the cross section for √ s . 0.8 GeV, until the onset of D-wave contributions. In this way, were new more precise data on γγ → ππ available one could then discern among different parameterizations of the ππ isoscalar S-wave. We finally calculate the width of the σ resonance to γγ and obtain Γ(σ → γγ) = 1.5± 0.3 KeV.
منابع مشابه
ar X iv : 0 70 8 . 16 59 v 2 [ he p - ph ] 6 N ov 2 00 7 Improved dispersion relations for γγ → π 0 π 0
We perform a dispersive theoretical study of the reaction γγ → ππ emphasizing the low energy region. The large source of theoretical uncertainty to calculate the γγ → ππ total cross section for √ s & 0.5 GeV within the dispersive approach is removed. This is accomplished by taking one more subtraction in the dispersion relations, where the extra subtraction constant is fixed by considering new ...
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