Exclusive differential spectra in color-singlet processes at hadron colliders are benchmark observables that have been studied to high precision in theory and experiment.
We present an effective-theory framework utilizing soft-collinear effective theory to incorporate massive (bottom) quark effects into resummed differential distributions, accounting for both heavy-quark initiated primary contributions to the hard scattering process as well as secondary effects from gluons splitting into heavy-quark pairs.
We discuss a variable flavor number scheme (VFNS) for the Drell-Yan process for the vector-boson transverse momentum qT as an example of an exclusive observable. The theoretical description depends on the hierarchy between the hard, mass, and the qT scale, ranging from the decoupling limit qT≪m to the massless limit m≪qT. The phenomenologically relevant intermediate regime m∼qT requires in particular quark-mass dependent beam and soft functions. We find that the rapidity divergences are different from the massless case and we discuss features of the resulting rapidity evolution. Our results will allow for a detailed investigation of quark-mass effects in the ratio of W and Z boson spectra at small qT, which is important for the precision measurement of the W-boson mass at the LHC.
