Rapidity dependence of nuclear coalescence: Impact on cosmic ray antinuclei

Upcoming studies at the CERN Large Hadron Collider (LHC) aim to extend the rapidity coverage in measurements of the production cross section of antinuclei $\overline{d}$ and $\overline{{}^3\mathrm{He}}$. I illustrate the impact of such studies on cosmic ray (CR) flux predictions, important, in turn, for the interpretation of results from CR experiments. I show that, in terms of the rapidity effect, covering the range $\left|y\right|<1.5$ at the LHC should be sufficient for the astrophysical CR calculation. Important extrapolation remains in other aspects of the problem, notably, $\sqrt{s}$.

Figure 1

Impact of rapidity cut on predicted CR antinuclei fluxes.

Figure 2

Proton flux-weighted, $p_{at}$-integrated differential cross section for $\overline{d}$ production. (a) No rapidity cut. (b) Nulling kinematic regions with $\left|y\right|<0.475$.

Figure 3

Kinematics and rapidity regions for $\overline{d}$ production. The generally allowed kinematic region is above the blue solid line (in the direction of the dashed line). The region $\left|y\right|<0.475$ is between the green solid lines (in the direction of the dashed line).

Figure 4

Proton flux-weighted, $p_{at}$-integrated differential cross section for $\overline{p}$ (top panels), $\overline{d}$ (middle panels), and $\overline{{}^3\mathrm{He}}$ (middle panels) production. Left panels: No rapidity cut. Right panels: Nulling kinematic regions with $\left|y\right|<0.475$.

Figure 5

$p_{at}$-integrated (not proton-flux weighted) differential cross section for $\overline{p}$ (top panels), $\overline{d}$ (middle panels), and $\overline{{}^3\mathrm{He}}$ (middle panels) production. Left panels: No rapidity cut. Right panels: Nulling kinematic regions with $\left|y\right|<0.475$.