1211.6050 (M. Cannoni)

Reanalysis of nuclear spin matrix elements for dark matter
spin-dependent scattering    [PDF]

M. Cannoni

We show how to include in the existing calculations the corrections to the isovector coupling arising in chiral effective field theory recently found in Ref. Menendez. The dominant effect can be taken into account by conveniently redefining the static spin matrix elements $<\mathbf{S}_{p,n}>$: the largest one is reduced, on average, a 10%. To show the impact of these corrections we recalculate the limits on the WIMP-proton spin dependent cross scetion set by COUPP. We also give practical formulas to obtain $<\mathbf{S}_{p,n}>$ given the structure functions in the various formalisms/notations existing in literature. We argue that the standard treatment of the spin-dependent cross section in terms of three independent isospin functions, $S_{00}(q)$, $S_{11}(q)$, $S_{01}(q)$, is redundant in the sense that the interference function $S_{01}(q)$ is the double product $|S_{01}(q)|=2\sqrt{S_{00}(q)}\sqrt{S_{11}(q)}$.

View original: http://arxiv.org/abs/1211.6050