Search for three-nucleon short-range correlations in light nuclei

We present new data probing short-range correlations (SRCs) in nuclei through the measurement of electron scattering off high-momentum nucleons in nuclei. The inclusive ${}^4\mathrm{He}/{}^3\mathrm{He}$ cross section ratio is observed to be both $x$ and $Q^2$ independent for $1.5<x<2$, confirming the dominance of two-nucleon short-range correlations. For $x>2$, our data support the hypothesis that a previous claim of three-nucleon correlation dominance was an artifact caused by the limited resolution of the measurement. While 3N-SRCs appear to have an important contribution, our data show that isolating 3N-SRCs is significantly more complicated than for 2N-SRCs.

Figure 1

The ${}^4\mathrm{He}/{}^3\mathrm{He}$ cross section ratio for $Q^2>1.4{\mathrm{GeV}}^2$, along with results from CLAS [17] and Hall C (E02-019) [18]. The error bars include statistical and systematic uncertainties; the 5.1% scale uncertainty is not shown.

Figure 2

The ${}^4\mathrm{He}/{}^3\mathrm{He}$ (top) cross section ratios for all angles. The solid lines are ratios from our $y$-scaling cross section model based on a parameterized longitudinal momentum distribution $F\left(y\right)$. The 5.1% normalization uncertainty is not shown.

Figure 3

Cross sections of ${}^2\mathrm{H}$, ${}^3\mathrm{He}$, ${}^4\mathrm{He}$, and ${}^{12}\mathrm{C}$ at ${25}^{\circ }$. Only statistical uncertainties are shown. The dashed lines show our cross section model.