  We propose the $pp \rightarrow \text{jet} + \gamma $ as a new process for
studying the Transverse Momentum Dependent Parton Distribution Functions
(TMDs). To do so, we developed a novel framework for the jet-$\gamma$ imbalance
in $pp \rightarrow \text{jet} + \gamma $ using Soft Collinear Effective Theory.
The new framework opens up many new insights to the TMDs which the current TMD
studies confined to the Drell-Yan and semi-inclusive deep inelastic scattering
processes cannot achieve. The established formalism provides, for the first
time, a first principle prediction of the jet-$\gamma$ imbalance in $pp$
collisions and therefore a first direct probe of the factorization breaking
effects when compared with the future experimental data. If the factorization
breaking effects are found small, the process will offer the unique
sensitivities to both the polarized and un-polarized quark/gluon TMDs. We
demonstrate the predictive power of the framework by calculating each component
in the formalism to the next-to-leading order accuracy and by realizing the
next-to-leading-logarithmic evolution. We provide the first numerical estimates
for this process, for both the unpolarized cross section and the Sivers
asymmetry.
