Abstract
Background: The neutrinoproduction of photons and pions from nucleons and nuclei is relevant to the background analysis in neutrino-oscillation experiments [for example, the MiniBooNE; MiniBooNE Collaboration, A. A. Aquilar-Arevalo et al., Phys. Rev. Lett. 100, 032301 (2008)]. The production from nucleons and incoherent production with have been studied in B. D. Serot and X. Zhang, Phys. Rev. C 86, 015501 (2012); and X. Zhang and B. D. Serot, Phys. Rev. C 86, 035502 (2012).
Purpose: Study coherent productions with . Also address the contributions of two contact terms in neutral current (NC) photon production that are partially related to the proposed anomalous , boson, and photon interactions.
Methods: We work in the framework of a Lorentz-covariant effective field theory (EFT), which contains nucleons, pions, the (1232) (s), isoscalar scalar () and vector () fields, and isovector vector () fields, and incorporates a nonlinear realization of (approximate) chiral symmetry. A revised version of the so-called “optimal approximation” is applied, where one-nucleon interaction amplitude is factorized out and the medium-modifications and pion wave function distortion are included. The calculation is tested against the coherent pion photoproduction data.
Results: The computation shows an agreement with the pion photoproduction data, although precisely determining the modification is entangled with one mentioned contact term. The uncertainty in the modification leads to uncertainties in both pion and photon neutrinoproductions. In addition, the contact term plays a significant role in NC photon production.
Conclusions: First, the contact term increases NC photon production by assuming a reasonable range of the contact coupling, which however seems not significant enough to explain the MiniBooNE excess. A high energy computation is needed to gain a firm conclusion and will be presented elsewhere. Second, the behavior of coherent neutrinoproductions computed here is significantly different from the expectation at high energy by ignoring the vector current contribution.
3 More- Received 8 August 2012
DOI:https://doi.org/10.1103/PhysRevC.86.035504
©2012 American Physical Society