RevModPhys.84.1307

Comparisons of neutrino reactions on 37 cl and the

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Unformatted text preview: rocess 37 Cað þ Þ37 K are prime example of this last constraint technique (Aufderheide et al., 1994). C. Theoretical calculations of neutrino-deuterium cross sections Next to hydrogen, no nuclear target is better understood than deuterium. Neutrino-deuterium scattering plays an important role in experimental physics, as heavy water (D2 O) was the primary target of SNO (Ahmad et al., 2001, 2002a, 2002b, 2004; Aharmin et al., 2005, 2007, 2008). The SNO experiment is able to simultaneously measure the electron and nonelectron component of the solar neutrino spectrum by comparing the charged current and neutral-current neutrino reactions on deuterium e þ d ! e À þ p þ p ðcharged currentÞ; (38) x þ d ! x þ n þ p ðneutral currentÞ: (39) Results from the experiment allowed confirmation of the flavor-changing signature of neutrino oscillations and verification of the Mikheyev-Smirnov-Wolfenstein mechanism (Wolfenstein, 1978; Mikheyev and Smirnov, 1989). Deuterium with its extremely small binding energy (Ebind ’ 2:2 MeV) has no bound final state after scattering. There exist two prominent methods for calculating such cross sections. The first method, sometimes referred to in the literature as the elementary-particle treatment (EPT) or at times the standard nuclear physics approach, was first introduced by Fujii and Yamaguchi (1964) and Kim and Primakoff (1965). The technique treats the relevant nuclei as fundamental particles with assigned quantum numbers. A transition matrix element for a given process is parametrized in terms of the nuclear form factors solely based on the transformation properties of the nuclear states, which in turn are constrained from complementary experimental data. Such a technique provides a robust method for calculating d scattering. Typically one divides the problem into two parts; the onebody impulse approximation terms and two-body exchange currents acting on the appropriate nuclear wave functions. In general, the calculation of these two-body currents presents the most difficulty in terms of verification. However, data gathered from n þ p ! d þ scattering provide one means of constraining any terms which may arise in d scattering. An additional means of verification, as discussed previously, involves the reproduction of the experimental tritium beta decay width, which is very precisely measured. An alternative approach to such calculations has recently emerged on the theoretical scene based on effective field theory (EFT) which has proven to be particularly powerful 1316 Joseph A. Formaggio and G. P. Zeller: From eV to EeV: Neutrino cross sections . . . in the calculations of d scattering (Butler and Chen, 2000; Butler, Chen, and Kong, 2001). EFT techniques make use of the gap between the long-wavelength and short-range properties of nuclear interactions. Calculations separate the long-wavelength behavior of the interaction, which can be readily calculated, while absorbing the omitted degrees of...
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