科研之友
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摘要
We present results for pion polarizabilities predicted using dispersion relations from our earlier amplitude analysis of world data on two photon production of meson pairs. The helicity zero polarizabi.lities are rather stable and insensitive to uncertainties in cross -channel exchanges. The need is first to confirm the recent result on (alpha(1)-beta(1)) for the charged pion by COMPASS at CERN to an accuracy of 10% by measuring the gamma gamma -> pi(+)pi(-) cross section to an uncertainty of 1%. Then the same polarizability, but for pi(0), is fixed to be (alpha(1)-beta(1))(pi 0) = (0.9 +/- 0.2) x 10(-4)fm(3). By analyzing the correlation between uncertainties in the meson polarizability and those in gamma gamma cross sections, we suggest experiments need to measure these cross sections between root S similar or equal to 350 and 600 MeV, The pi(0) pi(0) cross section then makes the (alpha(2) -beta(2))(pi 0) the easiest helicity-two polarizability to determine.
- 出版日期2016-12-30
