Neutrino Physics from the Cosmic Microwave Background and Large Scale
  Structure
  This is a report on the status and prospects of the quantification of
neutrino properties through the cosmological neutrino background for the Cosmic
Frontier of the Division of Particles and Fields Community Summer Study
long-term planning exercise. Experiments planned and underway are prepared to
study the cosmological neutrino background in detail via its influence on
distance-redshift relations and the growth of structure. The program for the
next decade described in this document, including upcoming spectroscopic galaxy
surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4,
will achieve sigma(sum m_nu) = 16 meV and sigma(N_eff) = 0.020. Such a mass
measurement will produce a high significance detection of non-zero sum m_nu,
whose lower bound derived from atmospheric and solar neutrino oscillation data
is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this
measurement will definitively rule out the inverted neutrino mass hierarchy,
shedding light on one of the most puzzling aspects of the Standard Model of
particle physics --- the origin of mass. This precise a measurement of N_eff
will allow for high sensitivity to any light and dark degrees of freedom
produced in the big bang and a precision test of the standard cosmological
model prediction that N_eff = 3.046.
