Lepton pair production in high energy μa scattering: cross sections, energy loss, and applications to underground lepton production

I reevaluate the total cross section and energy loss parameter β for lepton pair production from interactions of high energy muons with atomic targets. Using a detailed structure function analysis, this evaluation is valid for both elastic and inelastic scattering and includes the entire range of allowed momentum transfers. The formalism presented here is applied to both e+e- and τ+τ- pair production. This approach to the calculation of the cross section allows for a numerical evaluation of the energy distribution of the differential cross section. Using this numerical evaluation, and parameterizations for the atmospheric muon flux, I calculate the differential flux of high energy electrons and taus produced underground from incident muons, considering both conventional and prompt atmospheric muon fluxes. An approximate form for the differential charged current neutrino cross section is presented and used to calculate the differential flux of electrons and taus produced from incident neutrinos to compare to the production by incident muons. I also calculate the underground flux of photons produced via muon bremsstrahlung and discuss the electromagnetic background from these events. The relevance of high energy lepton production for underground Cherenkov detectors is discussed.