Deuteron Compton Scattering: A Random Walk
نویسنده
چکیده
In this sketch, some recent developments in Compton scattering off the deuteron are reviewed. The strong energy-dependence of the scalar magnetic dipole polarisability βM1 turns out to be crucial to understand the data from Saskatoon at 94 MeV. Chiral Effective Field Theory is used to extract the static iso-scalar dipole polarisabilities as ᾱs = 12.6± 1.4stat ± 1.0wavefu and β̄ s = 2.3± 1.7stat ± 0.8wavefu, in units of 10−4 fm3. Therefore, proton and neutron polarisabilities are identical within error bars. For details and a better list of references, consult e.g. Refs. [1, 2]. A PROBLEM WITH DEUTERON COMPTON SCATTERING As free neutrons can only rarely used in experiments, their properties are usually extracted from data taken on few-nucleon systems by subtracting nuclear binding effects. Take the polarisabilities: The photon field displaces the charged constituents of the neutron, inducing a non-vanishing multipole moment. Polarisabilities are a measure for the polarisation induced, i.e. for the global stiffness of the neutron against an electromagnetic field. They are canonically parameterised starting from the most general interaction between the nucleon N and an electro-magnetic field of non-zero energy ω:
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ar X iv : n uc l - th / 9 90 50 50 v 1 2 1 M ay 1 99 9 GAMMA - DEUTERON SCATTERING
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