  We propose the use of 1-jettiness, a global event shape, for exclusive single
jet production in lepton-nucleus deep inelastic scattering (DIS). We derive a
factorization formula, using the Soft-Collinear Effective Theory, differential
in the transverse momentum and rapidity of the jet and the 1-jettiness event
shape. It provides a quantitative measure of the shape of the final-state QCD
radiation in the presence of the hard jet, providing a useful powerful probe of
QCD and nuclear physics. For example, one expects differences in the observed
pattern of QCD radiation between large and small nuclei and these can be
quantified by the 1-jettiness event shape. Numerical results are given for this
new DIS event shape at leading twist with resummation at the
next-to-next-to-leading logarithmic (NNLL) level of accuracy, for a variety of
nuclear targets. Such studies would be ideal at a future EIC or LHeC
electron-ion collider, where a range of nuclear targets are planned.
